[RESOLVED] GridView - Show 'pretty name' of class property

Hi,

Sorry the title is a bit vague, I didn't know how to describe it.

The problem is very simple actually: I have a class Person that represents a person in my database. This class has a CategoryId property (int) and a Category property (type Category).
Category is a class that represents a category in my database.

csharp Code:

public class Person
{
    public int Id {get; set;}
    public string Firstname {get; set;}
    public string Lastname {get; set;}
    
    public int CategoryId {get; set;}
    public Category Category {get; set;}
}
 
public class Category
{
    public int Id {get; set;}
    public string CategoryName {get; set;}
}

I am displaying a list of these Persons in a GridView, and I would like to display the name of the Category (the CategoryName property to be precise). So I define this markup;

xml Code:

<asp:GridView runat="server" ID="personsGrid" AutoGenerateSelectButton="True" 
            AutoGenerateColumns="False" DataKeyNames="Id">
 
            <Columns>
                <asp:BoundField DataField="Id" HeaderText="Id" />
                <asp:BoundField DataField="Firstname" HeaderText="Firstname" />
                <asp:BoundField DataField="Lastname" HeaderText="Lastname" />
                <asp:BoundField DataField="Category" HeaderText="Category"  />
            </Columns>
 
        </asp:GridView>

While this works, the Category column obviously does not display the name of the category, but rather the type name (ProjectName.Category).

Usually I would solve this problem by one of two ways:

1. Override the ToString method of the Category class and return the name.
2. Add a readonly 'CategoryName' property to the Person class, where I return 'this.Category.CategoryName' (and then bind the column to this property instead).

In this case however, I am using the Entity Framework, and the Person and Category classes are automatically generated by the database model. I suppose I could edit the generated code manually, but I don't like that, since any change in the model will cause VS to re-generate the code and my changes would be lost. So these two methods are not going to work...


The simple question remains: how do I make the Category column show the CategoryName property of the object it represents, rather than just the type name?

In a DropdownList for example (which I am already using for the user to select a category when creating a person), I can set the DataTextField (to "CategoryName") and DataValueField (to "Id") properties and it displays the right name and uses the right value (the Id). I can't find anything similar for a BoundField though... Am I overlooking something obvious?

Another solution would be if I could tell the Entity Framework model to add another property to my Person class which returns the CategoryName of the Category. I can't find any way to do that though (I am a compleet noob in EF), so if anyone happens to know how to do that, that would work equally well :)


Thanks!

Hey,

I can see exactly what you want to do, but I honestly have no idea how to do it :)

I don't know enough about EF to say whether you can do this, but my gut feeling is that you can. The onlt thing that I can suggest in further investigation into this area, and see what turns up.

Sorry I can't be of more help!

Gary

I figured it out. Turns out the entity classes (Person, Category, etc) are partial classes, so I can just extend them wherever I want. As long as I keep their names the same I can now define a CategoryName property on the Person class in a different file (which won't be destroyed by the automatic generator).

Now you know! :p

Doh!!!

For course you can!! I have totally done that in the past, on a similar project, not using EF, but we created partial classes to "amend" and auto-generated file.

Glad to hear you got it working. Need to file this information "somewhere" so that I don't forget it :D

Gary

Yeah, I'm sure everyone on this forum has used this approach at least once... when creating a windows form or asp page :p It's exactly the same lol, the designer generates the code file that adds the controls to the form/page and sets their properties and the code you type in is the other half of the partial class :p Can't believe I didn't think of that sooner.

Yip, definitely a eureka moment :D

Glad you got it sorted out!!

Gary