Query all the documents by its file type from a Site and its all sub sites using SPSiteDataQuery

Introduction

I had to develop a web part where I had to query and display all the document items which the file extensions are “docx” under a particular site collection including its sub sites. I used SPSiteDataQuery class in order to achieve.

Solution

 
using (SPSite spSite = new SPSite(SPContext.Current.Web.Url))
            {
                using (SPWeb spWeb = spSite.OpenWeb())
                {
                    SPSiteDataQuery spSiteDataQuery = new SPSiteDataQuery();

                    spSiteDataQuery.Query =
                    @"<Where>
      <Eq>
         <FieldRef Name='DocIcon' />
         <Value Type='Computed'>docx</Value>
      </Eq>
   </Where>";
                    spSiteDataQuery.ViewFields = "<FieldRef Name='FileLeafRef' /><FieldRef Name='Editor' /><FieldRef Name='ContentType' />";
                    spSiteDataQuery.Lists = "<Lists ServerTemplate='101'/>"; //Set the list template by providing its template type id

                    spSiteDataQuery.Webs = "<Webs Scope='Recursive'/>";//Recursive: Current site and any subsite
                    //Scope='SiteCollection': all webs in the current site collection

                    //Get the results into a datatable
                    DataTable resultsTable = spWeb.GetSiteData(spSiteDataQuery);

                    
                    //Bind the results in to a asp grid view
                    GridView spGridView = new GridView();
                    spGridView.AutoGenerateColumns = true;
                    spGridView.DataSource = resultsTable;
                    spGridView.DataBind();

                    Controls.Add(spGridView);
                }
            }

 

Conclusion 
The results will look something as below. 

I have posted the my sln file here. Please download in case if you need
https://drive.google.com/file/d/0ByEnOE8DAdvhSTlnMDBuWDRuWTA/edit?usp=sharing

Reference: http://msdn.microsoft.com/en-us/library/ms409088.aspx