[RESOLVED] Want to hijack a SqlDataReader class so it can be sourced from multiple places

Ok - I'm using a simple SqlDataReader like this:

Code:

---

Using rsPrint As SqlDataReader = cmd.ExecuteReader

    ReDim strRS(0 To rsPrint.FieldCount - 1, 0 To 2)
.
.
.
    If rsPrint.HasRows Then
        If rsPrint.GetName(0) = "%%errormessage%%" Then
            strErrorMessage = rsPrint(0)
.
.
.
        End If
    End If

---

Simple stuff - using for example: .FieldCount, .HasRows, .GetName and more important, the default method which just returns a field (rsPrint(0) near the bottom of that code snippet).

What I'm looking to do is allow for this existing SQL access - calling that ExecuteReader at the top to work but also allow the "source" of the data to be a local array.

I'm thinking I can "override" each method and property to either "call the underlying" SqlDataReader code, or "use" my own code that is managing the local array instead.

I'm looking to not change any of the code in this Using Block - basically transparently source rsPrint from two different places.

I know how to do this in JavaScript - and believe I've seen it done here before.

I'm using VS 2012 unfortunately.

TIA! Steve

Would you be willing to change it just a LITTLE bit? If you used the IDataReader interface rather than a DataReader directly, then you could make any class you want that implements the IDataReader interface, and pass it in.

The IDataReader interface has some 34 items for you to implement, but since you are only using a few of them, you can leave the rest to their default implementation...maybe. I'm not sure what the default implementation is in VS2012, but it might be just an empty method. In 2019, the default implementation is this:

Code:

---

Throw New NotImplementedException()

---

Which at least tells you when you try to use something you didn't implement.

Seems IDataReader is missing .HasRows - oddly enough.

Why can't I just hide the SqlDataReader in a class that I make has the methods and other stubs that I need?

Way outside my wheelhouse here!

Code:

---

    If Not rsPrint.HasRows Then
.
.
.
        If rsPrint.HasRows Then

---

I'm confused about this. If you reach "If rsPrint.HasRows" how could it ever be True?

Quote:

---

Originally Posted by wes4dbt

Code:

---

    If Not rsPrint.HasRows Then
.
.
.
        If rsPrint.HasRows Then

---

I'm confused about this. If you reach "If rsPrint.HasRows" how could it ever be True?

---

The "..." indicates lots of code - I picked a bad spot to cut code out, lol!

I've always thought HasRows was utterly useless, though I admit to having used it once or twice. Whenever I used it, I always asked myself, "self, why are you using this?" to which I answered, "I have no idea, but I'm doing it anyways."

If you call .Read, you get a True or False. If you get False, then there are no rows left, whereas if you call True, then you have moved to that next row. The thing is, you can't do much of anything with a datareader until you DO move to that first row, so call .Read. If there are any rows, you move to the first row, which you'd have to do anyways, and if there are no rows, then you know that HasRows would also be false. So, it seems to me that HasRows is the same as .Read, except that it doesn't ALSO advance you to the next row.

Quote:

---

Originally Posted by Shaggy Hiker

I've always thought HasRows was utterly useless, though I admit to having used it once or twice. Whenever I used it, I always asked myself, "self, why are you using this?" to which I answered, "I have no idea, but I'm doing it anyways."

---

I read a row, then save the row, then advance to the next. Then see if we still have rows... That's a standard "report writer" engine trick to pre-evaluate break logic conditions.

Like I said in the OP, I'm looking to not TOUCH the inner code. It is old VB6 code ported to .Net - and it's huge. My client base would be really unhappy if I broke the report writer they rely on because I'm off on some crazy challenge to read data from an array instead of a SQL SPROC call.

Yeah since it was indented it looked like it was inside the first If statement. Good luck

Quote:

---

Originally Posted by Shaggy Hiker

Would you be willing to change it just a LITTLE bit? If you used the IDataReader interface rather than a DataReader directly, then you could make any class you want that implements the IDataReader interface, and pass it in.

The IDataReader interface has some 34 items for you to implement, but since you are only using a few of them, you can leave the rest to their default implementation...maybe. I'm not sure what the default implementation is in VS2012, but it might be just an empty method. In 2019, the default implementation is this:

Code:

---

Throw New NotImplementedException()

---

Which at least tells you when you try to use something you didn't implement.

---

You don't need to implement IDataReader yourself. It's already implemented in the DbDataReader class, which is the base class for SqlDataReader and pretty much every other ADO.NET data reader. You can just inherit that class and then override as required. You can then use either DbDataReader or IDataReader as your type. Note that DbDataReader does have the HasRows property.

Alternatively, use a DataTable as the alternative source instead of an array and then use a DataTableReader, which also inherits DbDataReader.

@jmc - thank you so much - I'll dig into DbDataReader tomorrow AM!

Quote:

---

Originally Posted by szlamany

@jmc - thank you so much - I'll dig into DbDataReader tomorrow AM!

---

I just took a closer look at the documentation and it seems that many (most? all?) of the members are declared abstract. That means that you would still have to provide your own implementation when inheriting that class.

But you'd only need to implement those pieces you are using, which sounds like a distinct minority of the methods.

It could be worthwhile checking out the source for the DataTableReader class to see how it uses a local data source. Reading from an array would be quite similar.

https://referencesource.microsoft.co...TableReader.cs

Ok - off to a slow start. Added a PUBLIC CLASS acsDataReader and much to my surprise when I typed INHERITS DbDataReader all of those METHODS and PROPERTIES appeared automatically. Nice job VS!

But I do not see any NEW methods to start off the data reader - where are those?

Code:

---

Public Class acsDataReader
    Inherits DbDataReader

    Public Overrides Sub Close()

    End Sub

    Public Overrides ReadOnly Property Depth As Integer
        Get

        End Get
    End Property

    Public Overrides ReadOnly Property FieldCount As Integer
        Get

        End Get
    End Property

    Public Overrides Function GetBoolean(ordinal As Integer) As Boolean

    End Function

    Public Overrides Function GetByte(ordinal As Integer) As Byte

    End Function

    Public Overrides Function GetBytes(ordinal As Integer, dataOffset As Long, buffer() As Byte, bufferOffset As Integer, length As Integer) As Long

    End Function

    Public Overrides Function GetChar(ordinal As Integer) As Char

    End Function

    Public Overrides Function GetChars(ordinal As Integer, dataOffset As Long, buffer() As Char, bufferOffset As Integer, length As Integer) As Long

    End Function

    Public Overrides Function GetDataTypeName(ordinal As Integer) As String

    End Function

    Public Overrides Function GetDateTime(ordinal As Integer) As Date

    End Function

    Public Overrides Function GetDecimal(ordinal As Integer) As Decimal

    End Function

    Public Overrides Function GetDouble(ordinal As Integer) As Double

    End Function

    Public Overrides Function GetEnumerator() As IEnumerator

    End Function

    Public Overrides Function GetFieldType(ordinal As Integer) As Type

    End Function

    Public Overrides Function GetFloat(ordinal As Integer) As Single

    End Function

    Public Overrides Function GetGuid(ordinal As Integer) As Guid

    End Function

    Public Overrides Function GetInt16(ordinal As Integer) As Short

    End Function

    Public Overrides Function GetInt32(ordinal As Integer) As Integer

    End Function

    Public Overrides Function GetInt64(ordinal As Integer) As Long

    End Function

    Public Overrides Function GetName(ordinal As Integer) As String

    End Function

    Public Overrides Function GetOrdinal(name As String) As Integer

    End Function

    Public Overrides Function GetSchemaTable() As DataTable

    End Function

    Public Overrides Function GetString(ordinal As Integer) As String

    End Function

    Public Overrides Function GetValue(ordinal As Integer) As Object

    End Function

    Public Overrides Function GetValues(values() As Object) As Integer

    End Function

    Public Overrides ReadOnly Property HasRows As Boolean
        Get

        End Get
    End Property

    Public Overrides ReadOnly Property IsClosed As Boolean
        Get

        End Get
    End Property

    Public Overrides Function IsDBNull(ordinal As Integer) As Boolean

    End Function

    Default Public Overloads Overrides ReadOnly Property Item(ordinal As Integer) As Object
        Get

        End Get
    End Property

    Default Public Overloads Overrides ReadOnly Property Item(name As String) As Object
        Get

        End Get
    End Property

    Public Overrides Function NextResult() As Boolean

    End Function

    Public Overrides Function Read() As Boolean

    End Function

    Public Overrides ReadOnly Property RecordsAffected As Integer
        Get

        End Get
    End Property
End Class

---

nvm - just needed to make a SUB NEW() of my own - moving along now!

Shaggy and JMC - thank you both! This is coming along very nicely!

Is just calling the SQLDataReader .CLOSE method enough to clean up or are there any other disposal requirements?

My implementation has two SUB NEW() methods.

One has just the SqlDataReader and the other is my local source - an IList(Of Dictionary(Of String, String)) - and some supporting info to consume this JSON array of info (shown at the bottom of this post).

Code:

---

Public Class acsDataReader
    Inherits DbDataReader

    Private _sdr As SqlDataReader = Nothing

    Private _doSdr As Boolean = False

    Private _style As String = ""
    Private _names As String = ""
    Private _columns As Integer = 0
    Private _start As Integer = 0
    Private _end As Integer = 0
    Private _source As IList(Of Dictionary(Of String, String))

    Sub New(sdr As SqlDataReader)
        _sdr = sdr
        _doSdr = True
    End Sub

    Sub New(strStyle As String, strNames As String, intColumns As Integer, intStart As Integer, intEnd As Integer _
                            , ilSource As IList(Of Dictionary(Of String, String)))
        _style = strStyle
        _names = strNames
        _columns = intColumns
        _start = intStart
        _end = intEnd
        _source = ilSource
        _doSdr = False
    End Sub

---

And my USING block has to start off a bit differently - allowing for both entry methods into the class.

Code:

---

Dim adr As acsDataReader = Nothing
If _SetData Then
    adr = New acsDataReader(_DataStyle, _DataNames, _ColumnCount, _DataStart, _DataEnd, _DataSource)
Else
    adr = New acsDataReader(cmd.ExecuteReader)
End If

Using rsPrint As acsDataReader = adr ' SqlDataReader = cmd.ExecuteReader

    ReDim strRS(0 To rsPrint.FieldCount - 1, 0 To 2)
    ReDim strLastRS(0 To rsPrint.FieldCount - 1, 0 To 2)
    ReDim curRSTotal(0 To lngRSTotal, 0 To rsPrint.FieldCount - 1, 0 To 2)
    ReDim curRSGTotal(0 To rsPrint.FieldCount - 1, 0 To 2)

    If Not rsPrint.HasRows Then

---

And the methods I'm writing down in the acsDataReader class just have to handle two methods for processing.

Code:

---

    Public Overrides ReadOnly Property FieldCount As Integer
        Get
            Dim intFC As Integer = 0
            If _doSdr Then
                intFC = _sdr.FieldCount
            Else
                intFC = _columns
            End If
            Return intFC
        End Get
    End Property

---

Bit of syntax sugar needed to make this work - but that was the only obstacle!

Below is the JavaScript code that is passing a JSON array of objects in an AJAX call to my web server!

I copy/pasted this data from a stored procedure call in SQL Server Management Studio and put it into that JSON string. I'm expecting identical results - PDF outputs from the web server in this case - to as if I had called the stored procedure on the webserver and read that SqlDataReader as the code had in place originally!

Happy day!

Code:

---

objExtra.offerdata = true
objExtra.datastyle = "listkvps";
objExtra.datanames = "ordinal0";
objExtra.datacolumns = "10"
arrFeed = [{'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '00-0-00000-1100-02', '5': 'E & G : CASH IN BANK : xxx', '6': '208851.91', '7': '185275.84', '8': '93681.67', '9': '117257.74'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '00-0-00000-1100-03', '5': 'E & G : CASH IN BANK : xxx', '6': '44983.94', '7': '23138.30', '8': '9706.77', '9': '31552.41'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '00-0-00000-1100-04', '5': 'E & G : CASH IN BANK : xxx', '6': '100473.61', '7': '78896.16', '8': '37011.58', '9': '58589.03'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '00-0-00000-1106-01', '5': 'E & G : CASH IN BANK - FIRST STATE : xxx', '6': '30925181.58', '7': '12997835.43', '8': '12774926.52', '9': '30702272.67'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '00-0-00000-1113-01', '5': 'E & G : AP CLEARING : xxx', '6': '269722.29', '7': '287535.82', '8': '165586.31', '9': '147772.78'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '10-0-00000-1106-01', '5': 'I & S : CASH IN BANK - FIRST STATE : xxx', '6': '298453.11', '7': '10838.92', '8': '183.24', '9': '287797.43'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '20-0-00000-1106-01', '5': 'PLANT : CASH IN BANK - FIRST STATE : xxx', '6': '1123694.45', '7': '208568.57', '8': '294643.13', '9': '1209769.01'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '30-0-00000-1106-01', '5': 'AUX : CASH IN BANK - FIRST STATE : xxx', '6': '-64466.23', '7': '1601387.89', '8': '2177416.50', '9': '511562.38'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '30-0-00000-1111-01', '5': 'AUX : SUSPENSE : xxx', '6': '-0.01', '7': '36.53', '8': '11.90', '9': '-24.64'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '30-0-00000-1111-04', '5': 'AUX : SUSPENSE : xxx', '6': '0.00', '7': '0.09', '8': '0.00', '9': '-0.09'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '40-0-00000-1106-01', '5': 'AGENCY  : CASH IN BANK - FIRST STATE : xxx', '6': '1312292.46', '7': '45065.76', '8': '132332.53', '9': '1399559.23'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '40-0-00000-1107-01', '5': 'AGENCY  : CASH IN BANK-BANK ONE (OTHER) : xxx', '6': '8041.37', '7': '539.09', '8': '0.00', '9': '7502.28'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '50-0-00000-1106-01', '5': 'SCHOL : CASH IN BANK - FIRST STATE : xxx', '6': '1653258.79', '7': '810356.57', '8': '533130.20', '9': '1376032.42'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '60-0-00000-1112-01', '5': 'LOAN : DIRECT LOANS : xxx', '6': '3079590.41', '7': '3079241.37', '8': '1903928.46', '9': '1904277.50'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '70-0-00000-1106-01', '5': 'OPP GRANT  : CASH IN BANK - FIRST STATE : xxx', '6': '5392619.21', '7': '5393119.21', '8': '740332.47', '9': '739832.47'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '70-0-00000-1109-01', '5': 'OPP GRANT  : STALE DATED CHECKS : xxx', '6': '-840.76', '7': '0.00', '8': '0.00', '9': '-840.76'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '80-0-00000-1106-01', '5': 'FEDERAL WORKSTUDY : CASH IN BANK - FIRST STATE : xxx', '6': '0.00', '7': '4522.00', '8': '19895.00', '9': '15373.00'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '90-0-00000-1106-01', '5': 'PAYROLL  : CASH IN BANK - FIRST STATE : xxx', '6': '777.77', '7': '5068751.04', '8': '5068383.59', '9': '410.32'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '00-0-00000-1110-01', '5': 'E & G : PETTY CASH - CHANGE FUND : xxx', '6': '2800.00', '7': '0.00', '8': '0.00', '9': '2800.00'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '00-0-00000-1110-02', '5': 'E & G : PETTY CASH - CHANGE FUND : xxx', '6': '800.00', '7': '0.00', '8': '0.00', '9': '800.00'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '00-0-00000-1110-04', '5': 'E & G : PETTY CASH - CHANGE FUND : xxx', '6': '100.00', '7': '0.00', '8': '0.00', '9': '100.00'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '30-0-00000-1110-01', '5': 'AUX : PETTY CASH - CHANGE FUND : xxx', '6': '6290.00', '7': '0.00', '8': '0.00', '9': '6290.00'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '30-0-00000-1110-02', '5': 'AUX : PETTY CASH - CHANGE FUND : xxx', '6': '600.00', '7': '0.00', '8': '0.00', '9': '600.00'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '30-0-00000-1110-04', '5': 'AUX : PETTY CASH - CHANGE FUND : xxx', '6': '400.00', '7': '0.00', '8': '0.00', '9': '400.00'}
    , {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '30-0-00000-1110-05', '5': 'AUX : PETTY CASH - CHANGE FUND : DO NOT USE', '6': '800.00', '7': '0.00', '8': '0.00', '9': '800.00'}
]

---

don't know if you can use this, it will pass your JSON string to a Datatable

Code:

---

Imports System.Text.RegularExpressions

Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim arrFeed As String = "[{'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '00-0-00000-1100-02', '5': 'E & G : CASH IN BANK : xxx', '6': '208851.91', '7': '185275.84', '8': '93681.67', '9': '117257.74'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '00-0-00000-1100-03', '5': 'E & G : CASH IN BANK : xxx', '6': '44983.94', '7': '23138.30', '8': '9706.77', '9': '31552.41'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '00-0-00000-1100-04', '5': 'E & G : CASH IN BANK : xxx', '6': '100473.61', '7': '78896.16', '8': '37011.58', '9': '58589.03'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '00-0-00000-1106-01', '5': 'E & G : CASH IN BANK - FIRST STATE : xxx', '6': '30925181.58', '7': '12997835.43', '8': '12774926.52', '9': '30702272.67'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '00-0-00000-1113-01', '5': 'E & G : AP CLEARING : xxx', '6': '269722.29', '7': '287535.82', '8': '165586.31', '9': '147772.78'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '10-0-00000-1106-01', '5': 'I & S : CASH IN BANK - FIRST STATE : xxx', '6': '298453.11', '7': '10838.92', '8': '183.24', '9': '287797.43'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '20-0-00000-1106-01', '5': 'PLANT : CASH IN BANK - FIRST STATE : xxx', '6': '1123694.45', '7': '208568.57', '8': '294643.13', '9': '1209769.01'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '30-0-00000-1106-01', '5': 'AUX : CASH IN BANK - FIRST STATE : xxx', '6': '-64466.23', '7': '1601387.89', '8': '2177416.50', '9': '511562.38'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '30-0-00000-1111-01', '5': 'AUX : SUSPENSE : xxx', '6': '-0.01', '7': '36.53', '8': '11.90', '9': '-24.64'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '30-0-00000-1111-04', '5': 'AUX : SUSPENSE : xxx', '6': '0.00', '7': '0.09', '8': '0.00', '9': '-0.09'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '40-0-00000-1106-01', '5': 'AGENCY  : CASH IN BANK - FIRST STATE : xxx', '6': '1312292.46', '7': '45065.76', '8': '132332.53', '9': '1399559.23'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '40-0-00000-1107-01', '5': 'AGENCY  : CASH IN BANK-BANK ONE (OTHER) : xxx', '6': '8041.37', '7': '539.09', '8': '0.00', '9': '7502.28'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '50-0-00000-1106-01', '5': 'SCHOL : CASH IN BANK - FIRST STATE : xxx', '6': '1653258.79', '7': '810356.57', '8': '533130.20', '9': '1376032.42'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '60-0-00000-1112-01', '5': 'LOAN : DIRECT LOANS : xxx', '6': '3079590.41', '7': '3079241.37', '8': '1903928.46', '9': '1904277.50'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '70-0-00000-1106-01', '5': 'OPP GRANT  : CASH IN BANK - FIRST STATE : xxx', '6': '5392619.21', '7': '5393119.21', '8': '740332.47', '9': '739832.47'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '70-0-00000-1109-01', '5': 'OPP GRANT  : STALE DATED CHECKS : xxx', '6': '-840.76', '7': '0.00', '8': '0.00', '9': '-840.76'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '80-0-00000-1106-01', '5': 'FEDERAL WORKSTUDY : CASH IN BANK - FIRST STATE : xxx', '6': '0.00', '7': '4522.00', '8': '19895.00', '9': '15373.00'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11100', '3': 'Cash', '4': '90-0-00000-1106-01', '5': 'PAYROLL  : CASH IN BANK - FIRST STATE : xxx', '6': '777.77', '7': '5068751.04', '8': '5068383.59', '9': '410.32'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '00-0-00000-1110-01', '5': 'E & G : PETTY CASH - CHANGE FUND : xxx', '6': '2800.00', '7': '0.00', '8': '0.00', '9': '2800.00'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '00-0-00000-1110-02', '5': 'E & G : PETTY CASH - CHANGE FUND : xxx', '6': '800.00', '7': '0.00', '8': '0.00', '9': '800.00'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '00-0-00000-1110-04', '5': 'E & G : PETTY CASH - CHANGE FUND : xxx', '6': '100.00', '7': '0.00', '8': '0.00', '9': '100.00'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '30-0-00000-1110-01', '5': 'AUX : PETTY CASH - CHANGE FUND : xxx', '6': '6290.00', '7': '0.00', '8': '0.00', '9': '6290.00'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '30-0-00000-1110-02', '5': 'AUX : PETTY CASH - CHANGE FUND : xxx', '6': '600.00', '7': '0.00', '8': '0.00', '9': '600.00'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '30-0-00000-1110-04', '5': 'AUX : PETTY CASH - CHANGE FUND : xxx', '6': '400.00', '7': '0.00', '8': '0.00', '9': '400.00'}"
        arrFeed &= ", {'0': '11000', '1': 'Cash and Cash Equivalents', '2': '11300', '3': 'Petty Cash', '4': '30-0-00000-1110-05', '5': 'AUX : PETTY CASH - CHANGE FUND : DO NOT USE', '6': '800.00', '7': '0.00', '8': '0.00', '9': '800.00'}"
        arrFeed &= "]"

        DataGridView1.DataSource = JsonToDataTable(arrFeed)
    End Sub

    Public Function JsonToDataTable(ByVal strJson As String) As DataTable
        Try
            strJson = strJson.Substring(strJson.IndexOf("[") + 1)
            strJson = strJson.Substring(0, strJson.IndexOf("]"))
            Dim rg As Regex = New Regex("(?<={)[^}]+(?=})")
            Dim mc As MatchCollection = rg.Matches(strJson)
            Dim tb As DataTable = Nothing

            For i As Integer = 0 To mc.Count - 1
                Dim strRow As String = mc(i).Value
                Dim strRows As String() = strRow.Split(","c)
                If tb Is Nothing Then
                    tb = New DataTable With {.TableName = ""}
                    For Each str As String In strRows
                        Dim dc As DataColumn = New DataColumn()
                        Dim strCell As String() = str.Split(":"c)
                        dc.ColumnName = strCell(0).ToString().Replace("""", "").Replace("'", "").Trim()
                        tb.Columns.Add(dc)
                    Next
                    tb.AcceptChanges()
                End If
                Dim dr As DataRow = tb.NewRow()
                For r As Integer = 0 To strRows.Length - 1
                    dr(r) = strRows(r).Split(":"c)(1).Trim().Replace("，", ",").Replace("：", ":").Replace("/", "").Replace("""", "").Replace("'", "").Trim()
                Next
                tb.Rows.Add(dr)
                tb.AcceptChanges()
            Next
            Return tb
        Catch ex As Exception
            MsgBox(ex.Message & vbNewLine, 48, "JsonToDataTable")
        Finally
        End Try
    End Function
End Class

---

but why do you have to use a Json when you extract the Data like you say...

Quote:

---

I copy/pasted this data from a stored procedure call in SQL Server Management Studio and put it into that JSON string.

---

can't you use the Data from the Database direct with the DataReader?

I haven't tried that, but I did try the IDataReader, and I believe it automatically includes IDisposable. If your class doesn't implement IDisposable, it probably should, if only to call the base Dispose method. Whether or not that does something significant, I can't say.

Quote:

---

Originally Posted by ChrisE

but why do you have to use a Json when you extract the Data like you say...

can't you use the Data from the Database direct with the DataReader?

---

About to market my report writer as an API call. I'll support lots of different data transmission methods. I've got a "mark up" language that goes along with it, for Crystal Reports-like formatting.

I've used it for my own business for decades - started in VB6, now ported to .Net running in IIS. I've been reading the "report layout specs" and "data" from SQL all this time. Now I'm exposing the "layout" and "data" to external submission.

Returns a PDF when done...

Quote:

---

Originally Posted by szlamany

About to market my report writer as an API call. I'll support lots of different data transmission methods. I've got a "mark up" language that goes along with it, for Crystal Reports-like formatting.

I've used it for my own business for decades - started in VB6, now ported to .Net running in IIS. I've been reading the "report layout specs" and "data" from SQL all this time. Now I'm exposing the "layout" and "data" to external submission.

Returns a PDF when done...

---

ah, got it
sounds good, and "light weight"

Quote:

---

Originally Posted by Shaggy Hiker

I haven't tried that, but I did try the IDataReader, and I believe it automatically includes IDisposable. If your class doesn't implement IDisposable, it probably should, if only to call the base Dispose method. Whether or not that does something significant, I can't say.

---

Shaggy - I know I marked this resolved - but quick question...

It made me use OVERLOADS because the base class had a Dispose() method. What would the base method know about what to dispose anyway? Am I supposed to call the base class dispose as well as the stuff I put in the Dispose() I wrote here?

Code:

---

    Public Overloads Sub Dispose() ' Implements IDisposable.Dispose
        If _sdr IsNot Nothing Then
            Try
                _sdr.Close()
            Catch ex As Exception

            End Try
            Try
                _sdr.Dispose()
            Catch ex As Exception

            End Try
        End If
        If _source IsNot Nothing Then
            _source = Nothing
        End If
    End Sub

---

I've gone back and forth on this one. In general, calling MyBase.Dispose seems like it would be safest, but I'm not sure what it would do. For example, had you just implemented the IDataReader and IDisposable interfaces on some class that you had, then there would BE no base class, and there would be nothing to dispose aside from anything that you wanted to dispose. In this case, since you inherited from the base class, then there is SOMETHING there, but it seems quite unlikely that what is there does anything meaningful such that it has something to dispose. After all, the derived class you have created is where all the work is happening, and there's really nothing in the base class that matters to you aside from its structure itself.

I don't have a means to see what is in the base class. JMC said that pretty nearly everything was abstract, so the base class may have no body at all, as it may serve as nothing more than a set of properties and methods with no implementation of their own. So, it seems like you would be safe not disposing the base class, but I can't be totally certain.

You don't overload the Dispose method. You override the Dispose(Boolean) method. Here's a basic disposable class:

vb.net Code:

Public Class Class1
    Implements IDisposable
 
    Private disposedValue As Boolean
 
    Protected Overridable Sub Dispose(disposing As Boolean)
        If Not disposedValue Then
            If disposing Then
                ' TODO: dispose managed state (managed objects)
            End If
 
            ' TODO: free unmanaged resources (unmanaged objects) and override finalizer
            ' TODO: set large fields to null
            disposedValue = True
        End If
    End Sub
 
    ' ' TODO: override finalizer only if 'Dispose(disposing As Boolean)' has code to free unmanaged resources
    ' Protected Overrides Sub Finalize()
    '     ' Do not change this code. Put cleanup code in 'Dispose(disposing As Boolean)' method
    '     Dispose(disposing:=False)
    '     MyBase.Finalize()
    ' End Sub
 
    Public Sub Dispose() Implements IDisposable.Dispose
        ' Do not change this code. Put cleanup code in 'Dispose(disposing As Boolean)' method
        Dispose(disposing:=True)
        GC.SuppressFinalize(Me)
    End Sub
 
End Class

That code was all added by VS, once the Implements line was added. Note the comment in the Dispose method:

Quote:

---

Do not change this code. Put cleanup code in 'Dispose(disposing As Boolean)' method

---

You should be overriding the Dispose(Boolean) method, putting your cleanup code there and then calling the base implementation. When the consuming code calls Dispose, it's actually calling the method inherited from the base class. That method then calls the overriding Dispose(Boolean) method in your class, which will do your cleanup and then pass off to the base class to do its cleanup, if any.

I would suggest ALWAYS calling the base method. If nothing else, you will be safe if you ever change the base class to something else that does have code in its Dispose(Boolean) method.

Actually, my previous post is true in general but not quite in this case. Here's the IDisposable implementation from the DbDataReader class, taken from the source code I linked to earlier:

Code:

---

        public void Dispose() {
            Dispose(true);
        }
   
        protected virtual void Dispose(bool disposing) {
            if (disposing) {
                Close();
            }
        }

---

So, Dispose calls Dispose(Boolean) and Dispose(Boolean) calls Close. Here's that Close method:

Code:

---

        virtual public void Close()
        {
        }

---

So, Close is an Overridable method that does nothing by default. That means that you should be overriding the Close method and putting your cleanup code there. While it won't actually make a difference whether you call the base method or not, I recommend that you do, for consistency and for the very small chance of avoiding an issue if you change the base class later. When all that is done, everything will work when using your class whether the consuming code calls Close, calls Dispose explicitly or implicitly (via Using) or the object is finalised by the system.

@jmc - thanks - that makes a whole lot more sense. I was fighting to OVERLOAD the DISPOSE method, when the base DISPOSE method was setup to call my OVERRIDES CLOSE method.

But to clarify - in this case I would NOT want to then call MyBase.Dispose() from my OVERRIDES CLOSE method, because that would be calling the caller that called me - right?

Isn't my OVERRIDES CLOSE method being called by the Base DISPOSE method?

Quote:

---

Originally Posted by szlamany

But to clarify - in this case I would NOT want to then call MyBase.Dispose() from my OVERRIDES CLOSE method, because that would be calling the caller that called me - right?

---

That's correct. The work gets done in the Close method. If the code calls Close then that's it. If the code calls Dispose, as would be done with a Using block, then Dispose will call Dispose(Boolean) and that will call Close.

Quote:

---

Originally Posted by szlamany

Isn't my OVERRIDES CLOSE method being called by the Base DISPOSE method?

---

Yes, the overriding method in your derived class is what will be executed, which is why that would need to call the base method if it contained and code.

This article is very clear

https://docs.microsoft.com/en-us/dot...enting-dispose

and I am following the section titled "Implement the dispose pattern for a derived class"

Quote:

---

Originally Posted by szlamany

I am following the section titled "Implement the dispose pattern for a derived class"

---

That would be the wrong thing to do. If you do that then calling Close will not actually do anything useful. As we have already established, calling Dispose invokes the Close method but not vice versa, so it is the Close method you need to override and put your code in. The actual code you put in the Close method would do the same thing but it should be in Close, not in Dispose(Boolean).

Quote:

---

Originally Posted by jmcilhinney

That would be the wrong thing to do...

---

And testing here has proven that out to be quite true!

All I need is just to OVERRIDE the CLOSE() - as shown below. MyBase.Dispose() or MyBase.Dispose(true) were both tried (at the bottom - commented out) - they both called my Close() in a loop - not good.

Code:

---

    Public Overrides Sub Close()
        If _doSdr Then
            Try
                _sdr.Close()
            Catch ex As Exception

            End Try
            Try
                _sdr.Dispose()
            Catch ex As Exception

            End Try
        Else
            If _source IsNot Nothing Then
                _source = Nothing
            End If
        End If
        ' MyBase.Dispose()        *** This does not work - it calls the CLOSE in a loop!
        ' MyBase.Dispose(true)  *** This does not work - it calls the CLOSE in a loop!
    End Sub

---

I also tried this - from the that article I linked to - and it's not good either. So I guess the pattern I'm using is not referred to in that link at all.

Code:

---

    Protected Overrides Sub Dispose(disposing As Boolean)
        If _disposed Then Return

        If disposing Then
            Close()
        End If

        _disposed = True

        MyBase.Dispose(disposing)
    End Sub

---

Bottom line - just handle the CLOSE() and all is well.

Your Close method should not be calling the base Dispose method. It should be calling the base Close method. Generally speaking, you can override a method to replace it or extend it. In the former case you would not call the base method and in the latter case you would. It's academic in this case because, even though you're extending the base Close method, it's actually empty. Let's say that, in future, you change your class to inherit some other class that inherits DbDataReader instead of inheriting it directly yourself. What if that class has some code in its Close method? Your Close method needs to call the base Close method in order for that code to be executed.

There is no BASE CLOSE method - I tried that in testing as well - MyBase.Close() does not exist to call...

And I did not call the DISPOSE from CLOSE - I was just testing test to see what it would do - and it did what I would expect (which was call CLOSE multiple times).

I think I'm all set here.

Quote:

---

Originally Posted by szlamany

There is no BASE CLOSE method

---

That's not true. The code in post #24 was copied directly from the source code for the DbDataReader class. How could you override a method in the first place if it didn't exist in the base class? Here's a class that I just created that compiles just fine. The relevant part is at the very bottom. All I did was start typing "Overrides" and then selected the Close method from the Intellisense list and the rest was added automatically. Not sure whether that was courtesy of VS or ReSharper but the point is that it's there and it compiles.

vb.net Code:

Imports System.Data.Common
 
Public Class CustomDataReader
    Inherits DbDataReader
 
    Public Overrides ReadOnly Property Depth As Integer
    Public Overrides ReadOnly Property FieldCount As Integer
    Public Overrides ReadOnly Property HasRows As Boolean
    Public Overrides ReadOnly Property IsClosed As Boolean
    Public Overrides ReadOnly Property RecordsAffected As Integer
 
    Default Public Overrides ReadOnly Property Item(ordinal As Integer) As Object
        Get
        End Get
    End Property
 
    Default Public Overrides ReadOnly Property Item(name As String) As Object
        Get
        End Get
    End Property
 
    Public Overrides Function GetDataTypeName(ordinal As Integer) As String
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetEnumerator() As IEnumerator
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetFieldType(ordinal As Integer) As Type
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetName(ordinal As Integer) As String
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetOrdinal(name As String) As Integer
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetBoolean(ordinal As Integer) As Boolean
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetByte(ordinal As Integer) As Byte
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetBytes(ordinal As Integer, dataOffset As Long, buffer() As Byte, bufferOffset As Integer, length As Integer) As Long
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetChar(ordinal As Integer) As Char
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetChars(ordinal As Integer, dataOffset As Long, buffer() As Char, bufferOffset As Integer, length As Integer) As Long
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetDateTime(ordinal As Integer) As Date
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetDecimal(ordinal As Integer) As Decimal
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetDouble(ordinal As Integer) As Double
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetFloat(ordinal As Integer) As Single
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetGuid(ordinal As Integer) As Guid
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetInt16(ordinal As Integer) As Short
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetInt32(ordinal As Integer) As Integer
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetInt64(ordinal As Integer) As Long
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetString(ordinal As Integer) As String
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetValue(ordinal As Integer) As Object
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function GetValues(values() As Object) As Integer
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function IsDBNull(ordinal As Integer) As Boolean
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function NextResult() As Boolean
        Throw New NotImplementedException()
    End Function
 
    Public Overrides Function Read() As Boolean
        Throw New NotImplementedException()
    End Function
 
    ''' <inheritdoc />
    Public Overrides Sub Close()
        MyBase.Close()
    End Sub
 
End Class

With MyBase.,Close() compile gets this error - did I screw up earlier and hurt this code

Code:

---

Error        149        'MyBase' cannot be used with method 'Public MustOverride Sub Close()' because it is declared 'MustOverride'.        C:\Users\szlam_000\OneDrive\ACS\AWC\ACSReport\acsReportWriter.vb        3643        9        C:\...\AWC\

---

Quote:

---

Originally Posted by szlamany

With MyBase.,Close() compile gets this error - did I screw up earlier and hurt this code

Code:

---

Error        149        'MyBase' cannot be used with method 'Public MustOverride Sub Close()' because it is declared 'MustOverride'.        C:\Users\szlam_000\OneDrive\ACS\AWC\ACSReport\acsReportWriter.vb        3643        9        C:\...\AWC\

---

---

Hmmm... something funny going on there. That error message suggests that the DbDataReader.Close method is declared abstract (the C# equivalent of MustInherit) but, as you can see from the code in post #24, that method is actually declared virtual (the C# equivalent of Overridable). I'm not sure whether that declaration has changed at some point. What version of .NET are you targeting?

Quote:

---

Originally Posted by jmcilhinney

Hmmm... something funny going on there. That error message suggests that the DbDataReader.Close method is declared abstract (the C# equivalent of MustInherit) but, as you can see from the code in post #24, that method is actually declared virtual (the C# equivalent of Overridable). I'm not sure whether that declaration has changed at some point. What version of .NET are you targeting?

---

I just checked the documentation and, in fact, the declaration was changed in .NET Framework 4.6. It was introduced to .NET Core in version 2.0 and it was virtual there, so maybe they decided to fix what they considered a mistake from the get-go in .NET Core and made the change in .NET Framework too. So, in .NET Framework 4.6 or later you could call the base method but it contains no code anyway, but you can't call it at all in earlier versions. Mystery solved.

Quote:

---

Originally Posted by jmcilhinney

...What version of .NET are you targeting?

---

Quote:

---

Originally Posted by szlamany

I'm using VS 2012 unfortunately.

---

Yes - using older VS and sticking with older versions of .Net. I keep all my clients running the exact same backend code base and some of the web servers they are using can be quite old and sometimes quite difficult for me to get access to.

I really appreciate all your assistance - thank you very much!

Pondering the change in declaration of the Close method, my guess would be that they made the change so that you aren't forced to implement the Close method if you don't actually need to close anything. I can imagine a data reader that cached the data internally and had no need to perform any action when closing, so overriding the Close method would serve no purpose. I can't think of any other reason that they would have changed it.