FormView ConvertEmptyStringToNull and binding

Question

I'm using a FormView with an ObjectDataSource and binding using <%# Bind("WhateverProp") %> - and all of my nullable columns are coming back with default values of the type in them.

It appears that the FormView object doesn't have a ConvertEmtpyStringToNull property like the other binding containers do. I've found articles suggesting that this was a bug in VS 2005 / .Net 2.0 - but don't see any saying what the resolution was.

Does anyone have any suggestions as to how I can work around this without just re-capturing all of the fields in the ODS_Inserting event? I'd rather not have to write code to re-bind all of my bound fields on the form just to test for nulls.

score 6 · Accepted Answer · answered Sep 25 '09 at 19:42

6

Struggled with it too. For a dropdownlist, I do that:

AppendDataBoundItems="true"


<asp:ListItem Text="" Value=""></asp:ListItem>

For my ObjectDataSource, even thoug my UpdateMethod takes a single parameter, the entity, I add Update params for each Nullable Field of the Entity with convert to NULL

<UpdateParameters>
    <asp:Parameter Name="No_Empl_Ferme" Type="Int32" ConvertEmptyStringToNull="true" />
</UpdateParameters>

I do the same for the Insert.

Works fine.

answered Sep 25 '09 at 19:42

devMomentum

433
4
9

Just ran into this issue today - and re-read thru all of the answers again. Yours is defintely the most correct. You CAN specify parameter names even when using the DataObjectTypeName property on the ODS. Good answer - I've changed the marked answer to point to yours. – Scott Ivey Mar 16 '11 at 16:27
This also solves a similar issue whereby ObjectDataSource throws an exception if a bound textbox gets disabled on the client-side before being submitted. Adding an explicit parameter solved this. – WickyNilliams Jun 27 '12 at 15:28

score 2 · Answer 2 · answered Apr 16 '09 at 13:37

I ended up doing this - kind of a shotgun approach, but in this case all of my empty string values should be nulls. I've also considered using a string array in the code to specify which values should be nulled - and then could just loop thru the string array instead of over all of the values.

protected void RequestItemFormView_ItemInserting(object sender, FormViewInsertEventArgs e)
{
    for (int i = 0; i < e.Values.Count - 1; i++)
    {
        if (e.Values[i].ToString() == string.Empty)
        {
            e.Values[i] = null;
        }
    }
}

score 1 · Answer 3 · answered Feb 02 '10 at 12:29

Quote: Tonio - i'm not using individual params, but DataObjectTypeName instead. My insert method takes a single param, and that's the business object that I want to have saved back to the database. – Scott Ivey May 1 at 12:57

I've fixed it like this:

 protected void FormViewSettings_ItemUpdating(object sender, FormViewUpdateEventArgs e)
  {
     OrderedDictionary values = e.NewValues as OrderedDictionary;

     var personID = values["PersonID"];

     if (string.IsNullOrEmpty(personID.ToString()))
     {
        values.Remove("PersonID");
        values.Add("PersonID", null);
     }
  }

It's a little hack but it works fine. This way you can set the object property to null instead of string.empty without using the ConvertEmptyStringToNull setting.

score 1 · Answer 4 · answered Apr 24 '09 at 15:34

1

In your Object DataSource, you need to add InsertParameters for each of your nullable type with the Attribute ConvertEmtpyStringToNull="True" :

<InsertParameters>
   <asp:Parameter Name="NullableFieldName" Type="Int32" ConvertEmptyStringToNull="true"  />            
</InsertParameters>

answered Apr 24 '09 at 15:34

Tonio - i'm not using individual params, but DataObjectTypeName instead. My insert method takes a single param, and that's the business object that I want to have saved back to the database. – Scott Ivey May 01 '09 at 12:57
Tonio - on a re-read - you were half there, so +1 for that. @devMomentum has the more correct answer though, so he gets the marked answer. – Scott Ivey Mar 16 '11 at 16:29

FormView ConvertEmptyStringToNull and binding

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