Hi gang,

The article found here does a good job of describing the problem - dynamically adding where parameters to Linq queries, based on some text field.

I managed to work around this with the following queries, but have since added an additional filtering field, which would make the most sense to add dynamically, instead of rewriting each query:

1                IEnumerable dataImport = from ds in matches
2                                                       orderby ds.FileUrl ascending
3                                                       where ds.CampaignID == Convert.ToInt32(Session["CampaignID"].ToString())
4                                                       select ds;
5    
6    
7                // get TLP, CLP, or PLP
8                if (DDPageType.SelectedValue != "ALL" & DDPageType.SelectedValue != "UNDEFINED")
9                {
10                   dataImport = from ds in db.tbl_DataImportMasterLists
11                                orderby ds.FileUrl ascending
12                                where ds.CampaignID == Convert.ToInt32(Session["CampaignID"].ToString())
13                                && ds.PageType.ToUpper() == DDPageType.SelectedValue
14                                select ds;
15               }
16   
17               if (DDPageType.SelectedValue == "UNDEFINED")
18               {
19                   dataImport = from ds in db.tbl_DataImportMasterLists
20                                orderby ds.FileUrl ascending
21                                where ds.CampaignID == Convert.ToInt32(Session["CampaignID"].ToString())
22                                && (ds.PageType.ToUpper() != "TLP" 
23                                && ds.PageType.ToUpper() != "CLP" 
24                                && ds.PageType.ToUpper() != "PLP")
25                                select ds;
26               }
27   
28               //
29               // Retrieving data from DataImportMasterList
30               //
31               foreach (tbl_DataImportMasterList ds in dataImport)
32               {
33                   // build a page object
34                   pageObject.FileUrl = ds.FileUrl;
35                   pageObject.FileUrlDisplay = DisplayFileUrl(ds.FileUrl, ds.PageType);    // send page type for hover text
36                   pageObject.TrackUrl = ds.TrackUrl;
37                   .
38                   .
39                   .
40                   // add it to an ArrayList
41                   arrUlrList.Add(pageObject);
42   
43               }//foreach

Basically I use IEnumerable to create a data object I can loop through for results.  The appropriate query is selected based on some on-page criteria (easy to see).  

Now, I want to add a "CONTAINS" filter, based on a new text field on my form:

1                IQueryable matches = db.tbl_DataImportMasterChanges;
2                if (TxtStringSearch.Text.Length > 0)
3                {
4                    matches = matches.Where(row => row.Title.ToLower().Contains(TxtStringSearch.Text.ToLower().Trim()));
5                }

However, in line 1, at db, I get the following error:

Cannot implicitly convert type 'System.Data.Linq.Table<tbl_DataImportMasterChange>' to 'System.Linq.IQueryable<tbl_DataImportMasterList>'  

DataClassesDataContext db is an instance of my Linq-generated DataClasses.dbml.

 
So given this, the question is, how to dynamically create a linq query with (not only CONTAINS), but ORDER BY, etc, and be able to iterate through the results?

Thanks.
 

The libraries for it are included in the VS 2008 samples

http://code.msdn.microsoft.com/csharpsamples/Release/ProjectReleases.aspx?ReleaseId=8

or if you're into VB
http://msdn2.microsoft.com/en-us/ms789074.aspx

Hi tsanet,

To: So given this, the question is, how to dynamically create a linq query with (not only CONTAINS), but ORDER BY, etc, and be able to iterate through the results?

Based on your requirements, you can use ToList method on your results which can persist your data into memory. In this case, you can use the data later and of course can iterate on the results. Here's a sample codes for you. Hope this helps you!

select u).ToList();

Thanks.

 Thanks PureWeen,

I had actually stumbled across that site before, and glad I took a second look.

I added Dynamic.cs to my project, and voila, works great!

 
Below is the code, for those of you who may need it:

1                StringBuilder sbCondition = new StringBuilder();
2    
3                sbCondition.Append("CampaignID == " + Convert.ToInt32(Session["CampaignID"].ToString()));
4                // get TLP, CLP, or PLP
5                if (DDPageType.SelectedValue != "ALL" & DDPageType.SelectedValue != "UNDEFINED")
6                {
7                    sbCondition.Append("&& PageType.ToUpper() == \"" + DDPageType.SelectedValue + "\"");
8                }
9    
10               // no page definition
11               if (DDPageType.SelectedValue == "UNDEFINED")
12               {
13                   sbCondition.Append("&& PageType.ToUpper() <> \"Page1\"");
14                   sbCondition.Append("&& PageType.ToUpper() <> \"Page2\"");
15                   sbCondition.Append("&& PageType.ToUpper() <> \"Page3\"");
16               }
17   
18               // text search
19               if (TxtStringSearch.Text.Trim().Length > 0)
20               {
21                   sbCondition.Append(" && " + DDSearchText.SelectedValue + ".Contains(\"" + TxtStringSearch.Text + "\")");
22               }
23   
24               // build query
25               IEnumerable dataImport = from ds in db.tbl_MainCreatives
26                                                                  .Where(sbCondition.ToString())
27                                                                  .OrderBy(order)
28                                                                  select ds;
29   
30   
31   
32               //
33               // Retrieving data from DataImportMasterList
34               //
35               foreach (tbl_MainCreative ds in dataImport)
36               { ... }