Question

I have a List<string> of variable count, and I want to query (via LINQ) a table to find any items that contain any of those strings in the Text column.

Tried this (doesn’t work):

items = from dbt in database.Items          where (stringList.FindAll(s => dbt.Text.Contains(s)).Count > 0)          select dbt; 

Query would be something like:

select * from items where text like '%string1%' or text like '%string2%' 

Is this possible?

Answer 1

Check this article out to do what you want:
http://www.albahari.com/nutshell/predicatebuilder.aspx

This works like a dream. I essentially cut and pasted their code and got this back (with my own data-scheme of course):

SELECT [t0].[Id], [t0].[DateCreated], [t0].[Name] ... FROM [dbo].[Companies] AS [t0] WHERE ([t0].[Name] LIKE @p0) OR ([t0].[Name] LIKE @p1) 

Here is the code I ran for the proof of concept:

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Linq.Expressions;  namespace PredicateTest { class Program {     static void Main(string[] args)     {         DataClasses1DataContext dataContext = new DataClasses1DataContext();          Program p = new Program();         Program.SearchCompanies('test', 'test2');         var pr = from pi in  dataContext.Companies.Where(Program.SearchCompanies('test', 'test2')) select pi;     }      DataClasses1DataContext dataContext = new DataClasses1DataContext();      public static Expression<Func<Company, bool>> SearchCompanies(                                                   params string[] keywords)     {         var predicate = PredicateBuilder.False<Company>();         foreach (string keyword in keywords)         {             string temp = keyword;             predicate = predicate.Or(p => p.Name.Contains(temp));         }         return predicate;     }  }  public static class PredicateBuilder {     public static Expression<Func<T, bool>> True<T>() { return f => true; }     public static Expression<Func<T, bool>> False<T>() { return f => false; }      public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expr1,                                                         Expression<Func<T, bool>> expr2)     {         var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());         return Expression.Lambda<Func<T, bool>>               (Expression.OrElse(expr1.Body, invokedExpr), expr1.Parameters);     }      public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> expr1,                                                          Expression<Func<T, bool>> expr2)     {         var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());         return Expression.Lambda<Func<T, bool>>               (Expression.AndAlso(expr1.Body, invokedExpr), expr1.Parameters);     } } } 

I’d suggest going to the site for the code and explanation.

(I am leaving the first answer because it works well if you need an IN statement)