Hi All,

I am wondering if you could help me with this...I am quire new to linq and i am trying to construct a dynamic where clause

for my linq query now i have been looking all over the web for examples but i cant find anything that seem to work for me...

here is my query and i want my where clause to be composed of the following dynamic string returned by the method

CreateFilter():

this method builds up my query based on whether a user selected a series of drop down boxes and input data into text boxes or not .i.e it it does an AND or OR depending on what is selected or not selected

string[] words = createFilter().Split(new string[] { "\r\n" }, StringSplitOptions.None);

var queryWhere = dt.AsEnumerable();

String thisWord = word;

queryWhere = queryWhere.Where(Func<string>(word)(word.Contains(thisWord))); //this did not work!!!!! 6hours trying!!

IEnumerable<DataRow> query =

from c in dt.AsEnumerable()

//******************Different where clauses i was tring to use to make it work!!******************************************/

select c;

dtFormat = new DataTable();

if (dtFormat.Rows.Count != 0)

dtFormat = query.CopyToDataTable<DataRow>();

/// This Method builds the where Clause the LINQ Query

/// based on User selected criteria

/// <returns></returns>

StringBuilder filter = new StringBuilder();

string ValueDate = msddlValueDate.List.SelectedValue;

filter.Append("c.Field<string>(" + "ValueDate" + ") == msddlValueDate.List.SelectedItem.ToString() && \r\n ");

string Currency = msddlCurrency.List.SelectedValue;

string Product = msddlProduct.List.SelectedValue;

string CountryIssue = msddlCountry.List.SelectedValue;

string Location = msddlLocation.List.SelectedValue;

string Tag = msddlTag.List.SelectedValue;

 Here is something to get you started...

1            table = new DataTable("People");
2            table.Columns.Add("Firstname", typeof (string));
3            table.Columns.Add("Lastname", typeof (string));
4            table.Rows.Add(new object[] {"John", "Doe"});
5            table.Rows.Add(new object[] {"Jane", "Doe"});
6            table.Rows.Add(new object[] {"Donald", "Duck"});
7            table.Rows.Add(new object[] {"Jumping", "Jack"});
8    
9            bool filterOnFirstName = true;
10           bool filterOnLastName = false;
11    
12           var query = table.AsEnumerable();
13   
14           if (filterOnFirstName)
15           {
16               query = query.Where(r => ((string) r["Firstname"]).StartsWith("J"));
17           }
18   
19           if (filterOnLastName)
20           {
21               query = query.Where(r => ((string) r["Lastname"]).StartsWith("J"));
22           }
23   
24           var queryFinal = from q in query
25                            select new {FullName = q.Field<string>("Firstname") + " " + q.Field<string>("Lastname")};
26   
27           GridView1.DataSource = queryFinal;
28           GridView1.DataBind();

Hmmm....so it seems like no one knows how to do this then?

ShadowOfTheBeast:

Hmmm....so it seems like no one knows how to do this then?

Hmm... Do you still need help on this?  I thought the sample code that I gave before should be pretty clear and to the point to what you were asking.  Just need to customize it to fit your form.  Frankly I haven't find a way to combine that into one giant LINQ statement with all the conditions.  That's why I split them up into multiple LINQ queries which keep feeding into the next query and so on based on some conditions.