Programmatic parameter population with declarative data sources in ASP.NET 2.0

Jolly good tip Fritz.

Are there any particularly useful weblinks on such content?

Thanks
Gregor

Fritz, I know that my blog is not widely read by anyone but me, but I did post about this a few days ago. Mainly writing to see what you think of my original post:

http://blog.binaryocean.com/PermaLink,guid,a1ff6cab-dc2d-441c-8557-7dce920d4075.aspx

http://blog.binaryocean.com/PermaLink,guid,eca3c5a1-08c1-4226-bfb5-d36fddaef93b.aspx

I thurowly enjoy reading what you write.

-A

Cool Command-Line Stuff
[Via: kaevans ]
Programmatic parameter population with declarative data ...

Thanks for the link Andrew, It's always reassuring to see someone else use the same technique. Your blog looks like it has some great content, I'll keep an eye there in the future.
-Fritz

Hi Fritz,

Yes I have done this as well.

I must say that one of this things Microsoft seem to have missed is the concept of an <asp:PropertyParameter />.

Why do I think this is missing and important? Because you often get in a "pull" mindset with the new databinding model where you want to setup Control Parameters to pull their values from Session or Profile or the QueryString, etc. But it often breaks down and you need to use the "push" ie Event handling model, which makes the code harded to comprehend.

Wouldn't it be elegant to just define a couple of Page level properties like:
public DateTime Today
{
get { return DateTime.Now; }
}

public string UserName
{
get { return User.Identity.Name;
}

and then just include a param like:
<asp:PropertyParameter Name="filed_by" Property="UserName" />
<asp:PropertyParemeter Name=date_filed" Property="Today" />

This would allow you to keep the same mindset.

Lets all hit Scott G with this suggestion ;-)

Another reason you *need* this feature, is because ASP.NET 2 is really bad when splitting stuff between different user controls or between a master page and a page or user control. The data binding stuff in V2 seems really bad unless both the data source and data control are within the same page/control/masterpage. My suggestions would also be to use page level properties to solve this problem.

It's actually quite easy to roll your own:

using System;
using System.ComponentModel;
using System.Globalization;
using System.Web;
using System.Web.UI.WebControls;

[DefaultProperty("PropertyName")]
public class PagePropertyParameter : Parameter
{
public PagePropertyParameter(string name, TypeCode typeCode, string propertyName)
: base(name, typeCode)
{
PropertyName = propertyName;
}

public PagePropertyParameter(string name, string propertyName)
: base(name)
{
PropertyName = propertyName;
}

protected PagePropertyParameter(PagePropertyParameter original)
: base(original)
{
PropertyName = original.PropertyName;
}

public PagePropertyParameter()
{
}

[DefaultValueAttribute("")]
[Category("Parameter")]
public string PropertyName
{
get
{
object value = ViewState["PropertyName"];
if (null == value) return string.Empty;
return (string)value;
}
set
{
if (string.IsNullOrEmpty(value))
{
ViewState.Remove("PropertyName");
}
else
{
ViewState["PropertyName"] = value;
}
}
}

protected override Parameter Clone()
{
return new PagePropertyParameter(this);
}

protected override object Evaluate(HttpContext context, Control control)
{
string prop = this.PropertyName;
if (string.IsNullOrEmpty(prop)) return null;

IHttpHandler handler = context.Handler;
if (null == handler) return null;

return DataBinder.Eval(handler, prop);
}
}

Hi there. I love this tip. It's exactly what I'm looking for. I'm trying to adapt this to VB/Access, and I'm getting an odd error. Any ideas?

Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: BC30545: Property access must assign to the property or use its value.

Source Error:



Line 2: <script runat="server">
Line 3: Sub AccessDataSource_Inserting(ByVal sender As Object, ByVal e As SqlDataSourceCommandEventArgs)
Line 4: e.Command.Parameters["@UpdateBy"].Value = User.Identity.Name
Line 5: e.Command.Parameters["@LastUpdate"].Value = DateTime.Now.ToShortDateString()
Line 6: End Sub

VB uses '(' instead of '[' for indexing:
e.Command.Parameters("@UpdateBy").Value = User.Identity.Name

Thank you so much.

Thanks so much... Fritz has the answer again! :)

i need to change select parameter in "where" cluses in any part of source without "e"

Your blog is being added to my favorites now, thank you for this trick. In my case, I am using an objectdatasource with the onSelecting event, but it works very similar. Thx again.

I'm trying to do exactly the same thing using the ObjectDataSource and it's OnInserting and OnUpdating properties.

protected void insertCompany_LastChangeUserNameParam(object sender, ObjectDataSourceMethodEventArgs e)
{
// The business object expects a custom type. Build it
// and add it to the parameters collection.
CSI.Company c = (CSI.Company)paramsFromPage["c"];
c.LastChangeUserName = User.Identity.Name;

e.InputParameters.Clear();
e.InputParameters.Add("c", c);

}

I get "The OrderedDictionary is readonly and cannot be modified." on the e.InputParameters.Clear() line.

What am I doing wrong?

Just can't seem to get this to work. I get no error's - all other fields in the database update. Trying to do this against the objectdatasource.

Sub CommentsObject_Inserting(ByVal sender As Object, ByVal e As SqlDataSourceCommandEventArgs)
e.Command.Parameters("@user_name").Value = User.Identity.Name
e.Command.Parameters("@comment_date").Value = DateTime.Now.ToShortDateString()
End Sub


<asp:DetailsView ID="DetailsView1" runat="server" AutoGenerateRows="False" DataKeyNames="comment_id"
DataSourceID="CommentsObject" DefaultMode="Insert" Height="1px" Width="712px">
<Fields>
<asp:BoundField DataField="wine_user_name" HeaderText="wine_user_name" SortExpression="wine_user_name" InsertVisible="False" />
<asp:BoundField DataField="comment" HeaderText="comment" SortExpression="comment" />
<asp:BoundField DataField="comment_date" HeaderText="comment_date" SortExpression="comment_date" InsertVisible="False" />
<asp:BoundField DataField="wine_rating" HeaderText="wine_rating" SortExpression="wine_rating" />
<asp:BoundField DataField="comment_id" HeaderText="comment_id" InsertVisible="False" SortExpression="comment_id" />
<asp:BoundField DataField="wine_id" HeaderText="wine_id" SortExpression="wine_id" InsertVisible="False" />
<asp:CommandField ShowInsertButton="True" />
</Fields>
</asp:DetailsView>
<asp:ObjectDataSource ID="CommentsObject" runat="server" InsertMethod="Insert" OldValuesParameterFormatString="original_{0}"
SelectMethod="GetData" TypeName="winesTableAdapters.selectWineCommentTableAdapter">
<SelectParameters>
<asp:QueryStringParameter Name="wineid" QueryStringField="wineid" Type="Int32" />
</SelectParameters>
<InsertParameters>
<asp:Parameter Name="wine_user_name" Type="String" />
<asp:Parameter Name="comment" Type="String" />
<asp:Parameter Name="comment_date" Type="DateTime" />
<asp:Parameter Name="wine_rating" Type="Int32" />
<asp:QueryStringParameter Name="wine_id" QueryStringField="wineid" Type="Int32" />
</InsertParameters>
</asp:ObjectDataSource>

Perfect! Thanks for the information. I was looking for this for a _long_ time.

I receive an error message trying to use this with an AccessDataSource:

Parser Error Message: Literal content ('OnInserting="defectsDataSource_Inserting"') is not allowed within a 'System.Web.UI.WebControls.AccessDataSource'.

Source Error:


Line 78: OldValuesParameterFormatString="original_{0}" SelectCommand="SELECT [Cat_code], [SME_code], [Pub_code], [Pub_name], [Pub_date], [Pub_format], [Pub_location], [Pub_nopages] FROM [TblPubdetail]"
Line 79: UpdateCommand="UPDATE [TblPubdetail] SET [Pub_format] = ?, [Pub_location] = ?, [Pub_nopages] = ? WHERE [Cat_code] = ? AND [SME_code] = ? AND [Pub_code] = ? AND [Pub_name] = ? AND [Pub_date] = ? AND [Pub_format] = ? AND [Pub_location] = ? AND [Pub_nopages] = ?">
Line 80: OnInserting="defectsDataSource_Inserting"
Line 81: <InsertParameters>
Line 82: <asp:Parameter Name="Cat_code" Type="Int16" />

SuperSweet! (dont mistake the exclamation point for a "not")
;o)

I have to agree with David Taylor. Not having access to te page level is a real pain. You can access any of the controls using a ControlParameter but I have not to found a way to access the page itself.

Exactly what I was looking for! Thanks!

For those that were looking for the functionality described by David and Richard at the begining of the comments to this blog, you can pull values from page level properties using the following:

<asp:ControlParameter Name="UserName" ControlID="__Page" PropertyName="UserName" />

__Page is a *special* identifier for the current page object.

Hope that helps!

Bobby Diaz
Member of the .netTiers team.

I'm trying to convert this to VB too.
Code behind:
Sub SqlDataSource1_Inserting(ByVal sender As Object, ByVal e As SqlDataSourceCommandEventArgs)
e.Command.Parameters.Item("@UserLastUpdate").Value = User.Identity.Name
End Sub
Keep coming up with:
Cannot insert the value NULL into column 'UserLastUpdate', table 'C_Scheduler.dbo.tbl_Building'; column does not allow nulls. INSERT fails.


What's not working? Thanks for any suggestions.

OUTSTANDING! Thanks for the blog and thanks to Bobby Diaz for the final answer!

many many Thanks for the Solution that you have shared with us.

greetings from Germany :)))

This has helped me out.... Well Done tx for you post!!

THanks! hit the spot!

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