How to trim values using Linq to Sql?

Question

In the database, I have a table called Contact. The first name and other such string fields are designed to use a Char datatype (not my database design). My object Contact maps to a string type in the properties. If I wanted to do a simple test retrieving a Contact object by id, I would do something like this:

Contact contact = db.Contacts.Single(c => c.Id == myId);
Contact test = new Contact();
test.FirstName = "Martin";

Assert.AreEqual(test.FirstName, contact.FirstName);

The contact.FirstName value is "Martin " because of the char type. Where can I intercept the FirstName property when it is being loaded? OnFirstNameChanging(string value) does not get called on the initial load (contact), but does on the test object.

Answer 1

Contact contact = db.Contacts.Single(c => c.Id.Trim() == myId);

And check that the LINQ provider translates that into the appropriate SQL.

Answer 2

If you can't change the schema, you might want to make the designer generated accessor private/protected and create a public accessor to front-end the property in a partial class implementation. You can then Trim the value in the get accessor.

public partial class Contact
{

    public string RealFirstName
    {
       get { return this.FirstName.Trim(); }
       set { this.FirstName = value; }
    }

    ...
}

Answer 3

You can run a ForEach on your list of contacts before trying to search for Martin.

var contacts = db.Contacts.ForEach(c => c.FirstName = c.FirstName.Trim());
Contact contact = contacts.Single(c => c.Id == myId);
contact.FirstName // = "Martin"

But this way is not very easy to maintain if it has to be done for multiple fields.

Answer 4

It depends on the control you have over the schema and the code.

If the values are being set up by calling a constructor with all parameters, do the trims, etc as they are assigned to the member variables.

If they are being assigned to the properties (probably from the example), change the SET accessor so that it does the trim there.

You do have potential issues if you actually WANT leading or trailing spaces at some point though.

If you can't modify the base class code, try using partial classes, or inheriting from the class and overriding the properties there.

If you can't do that, then my last suggestion would be to write a factory class of some sort that you pass a created object to and it cleans it up per the rules you want.

Answer 5

Maybe you could put it in the OnLoaded() partial method? Note: I've never used this, but I assume it would look like this:

public partial class Contact
{
    partial void OnLoaded()
    {
        FirstName = FirstName.Trim();
    }
}