Modify the data source of a data view web part

Question

I have a dataView web part deployed in a template in multiple site collection. This dataView hasn't any query set up, so it loads a lot of items and this is slowing down my system.
Now I want to programmatically put a query overriding the existent (empty) one and I'm doing like this:
System.Web.UI.WebControls.WebParts.WebPart y = (System.Web.UI.WebControls.WebParts.WebPart)item;
Microsoft.SharePoint.WebPartPages.DataFormWebPart z = (Microsoft.SharePoint.WebPartPages.DataFormWebPart)item;
StringBuilder dataSourceString = new StringBuilder("<%@ Register TagPrefix=\"sharepoint\" Namespace=\"Microsoft.SharePoint.WebControls\" Assembly=\"Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c\" %>");
dataSourceString.Append("<%@ Register TagPrefix=\"WebPartPages\" Namespace=\"Microsoft.SharePoint.WebPartPages\" Assembly=\"Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c\" %>");
dataSourceString.Append("<sharepoint:SoapDataSource runat=\"server\" SelectUrl=\"http://intranet.contoso.com/sites/spc/_vti_bin/lists.asmx\" InsertUrl=\"\" UpdateUrl=\"\" DeleteUrl=\"\" SelectAction=\"http://schemas.microsoft.com/sharepoint/soap/GetListItems\" InsertAction=\"\" UpdateAction=\"\" DeleteAction=\"\" SelectPort=\"ListsSoap\" InsertPort=\"\" UpdatePort=\"\" DeletePort=\"\" SelectServiceName=\"Lists\" InsertServiceName=\"\" UpdateServiceName=\"\" DeleteServiceName=\"\" AuthType=\"Basic\" AuthUserName=\"contoso\\administrator\" AuthPassword=\"pass@word1\" WsdlPath=\"http://intranet.contoso.com/sites/spc/_vti_bin/lists.asmx?WSDL\" XPath=\"\" ID=\"SoapDataSource3\">");
dataSourceString.Append("<SelectCommand><soap:Envelope xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\"><soap:Body><GetListItems xmlns=\"http://schemas.microsoft.com/sharepoint/soap/\"><listName>Jobs</listName>");
dataSourceString.Append("<Query><Where><Eq><FieldRef Name=\"Title\" /><Value Type=\"Text\">2012_080_A_0</Value></Eq></Where></Query>");
dataSourceString.Append("<rowLimit>9999</rowLimit></GetListItems></soap:Body></soap:Envelope></SelectCommand><InsertCommand></InsertCommand><UpdateCommand></UpdateCommand><DeleteCommand></DeleteCommand></sharepoint:SoapDataSource>");
z.DataSourcesString = dataSourceString.ToString();
manager.SaveChanges(z);
In my code, I can see the DataSourceString changing, but if I refresh the page it is still loading all the data: why?!

Answer 1

Hi,
According to your description, my understanding is that you want to change the data view web part datasource programmatically.
We need to override the databind method like below:
public class ExtendedDataFormWebPart : DataFormWebPart
public override void DataBind()
this.DataSource = your own data source;
base.DataBind();
Here is a detailed code demo for your reference:
http://jamestsai.net/Blog/post/How-to-query-cross-site-lists-in-DataFormWebPart-Part-1-Build-your-own-data-source-for-DataFormWebPart.aspx
Best Regards
Jerry Guo
TechNet Community Support