Hi devoas,
You can easily combine multiple lambda expressions with the code bellow:
Expression<Func<Customer, bool>> filter1 = c => c.City.StartsWith("S");
Expression<Func<Customer, bool>> filter2 = c => c.City.StartsWith("M");
Expression<Func<Customer, bool>> filter3 = c => c.ContactTitle == "Owner";
Expression<Func<Customer, bool>>[] filterExpressions = new Expression<Func<Customer, bool>>[] { filter1, filter2, filter3 };
Func<Expression, Expression, BinaryExpression>[] operators = new Func<Expression, Expression, BinaryExpression>[] { Expression.OrElse , Expression.AndAlso};
Expression<Func<Customer, bool>> filter = null;
if (filterExpressions.Length > 0)
{
Expression body = filter1.Body;
for (int i = 1; i < filterExpressions.Length; i++)
{
body = operators[i - 1](body, filterExpressions[i].Body);
}
filter = Expression.Lambda<Func<Customer, bool>>(body, filter1.Parameters);
}
IObjectScope objectScope = ObjectScopeProvider1.GetNewObjectScope();
IQueryable<Customer> query = (from c in objectScope.Extent<Customer>() select c).Where(filter);
Notice that the Expression methods used are OrElse and AndAlso. They produce binary expressions.
The And and Or methods produce bitwise operations.
The result lambda expression will look like this:
filter = {c => ((c.City.StartsWith("S") || c.City.StartsWith("M")) && (c.ContactTitle = "Owner"))}
And the generated SQL will look like this:
"SELECT [CustomerID] AS COL1, [Address] AS COL2, [City] AS COL3, [CompanyName] AS COL4, [ContactName] AS COL5, [ContactTitle] AS COL6, [Country] AS COL7, [Fax] AS COL8, [Phone] AS COL9, [PostalCode] AS COL10, [Region] AS COL11 FROM [Customers] WHERE ([City] LIKE 'S%' OR [City] LIKE 'M%') AND [ContactTitle] = 'Owner' "
I hope this helps.
Do not hesitate to write again if you have more questions or suggestions.
Best wishes,
Jordan
the Telerik team