Question about Dynamic Expression API (System.Linq.Dynamic)

Question

Hi

 

I am trying to understand and utilize the Dynamic Expression API  available as System.Linq.Dynamic.

 

If I have a query like below:

var query =
    db.Customers.
    Where("City = @0", "London").
    OrderBy("CompanyName").
    Select("new(CompanyName as Name, Phone)");

 

with the Dynamic Expression API, would I be able to specify LIKE operator on the City field?

 

I want to do something like this:

 

var query =
    db.Customers.
    Where("City LIKE @0", "L").
    OrderBy("CompanyName").
    Select("new(CompanyName as Name, Phone)");

 

How can I do this?

 

Thanks much in advance!

 

Answer 1

Got it.

 

 

var query =
    db.Customers.
    Where("City.StartsWith(\"L\")").
    OrderBy("CompanyName").
    Select("new(CompanyName as Name, Phone)");

Answer 2

Another roadblock.

 

Is it possible to have the OR operator between filter criteria?

 

I am trying to do something like this:

 

var query =
    db.Customers.
    Where("City == @0 OR City == @1","London","Paris").
    OrderBy("CompanyName").
    Select("new(CompanyName as Name, Phone)");

 

 

Answer 3

Guess what? That's possible too.

 

 

   string condition1 = "FirstName.StartsWith(\"" + textBox1.Text + "\")";
   string condition2 = "FirstName.StartsWith(\"" + textBox2.Text + "\")";
    var q = db.Employees.Where(condition1 + " or " + condition2).Select("new(FirstName,LastName)");

Answer 4

S441,

I went through your code, its good. I have the similar situation but i expect the dynamic query to xml file, could you please tell me how to write the dynamic query to an xml file.