c# lambda expression convert from vb to c#

Question

I'm trying to convert this vb.net code to c#.

        If (txtCompanyName.Text.Trim() <> String.Empty) Then
            decals = decals.Where(Function(d As CT_Decal) (From c In db.CT_Companies Where c.CompanyName.Contains(txtCompanyName.Text.Trim()) Select c.CompanyID).ToList.Contains((From t In db.CT_Tanks Where t.CargoTankID = d.TankID Select t.CompanyID).Single.ToString()))
        End If

In c# I tried to put the code:

        if (txtCompanyName.Text.Trim() != string.Empty)
        {
                    decals = decals.Where(Function(CT_Decal d)(from c in db.CT_Companies 
                                                where c.CompanyName.Contains(txtCompanyName.Text.Trim())
                                                select c.CompanyID).ToList().Contains((from t in db.CT_Tanks                                                                                                    where t.CargoTankID == d.TankID 
                                                select t.CompanyID).Single.ToString()));

        }//end if

c# errors:

The name function does not exist and CT_Decal is a type but is used like a variable.

Does anybody know how to convert this properly?

Always use !String.IsNullOrEmpty(txtCompanyName.Text) instead of txtCompanyName.Text.Trim() != string.Empty — user153923
– user153923, Commented Feb 13, 2012 at 20:15
Also, the ToList() is redundant and the code shouldn’t compile in VB since Where expects a predicate but your lambda is returning a string. — Konrad Rudolph
– Konrad Rudolph, Commented Feb 13, 2012 at 20:17
@jp2code those expressions are not equivalent; they give different results if txtCompanyName.Text contains only whitespace characters. — phoog
– phoog, Commented Feb 13, 2012 at 20:21
@Konrad Rudolph, due to the complexity it's hard to see, but what's actually being returned is the outcome of the Contains method, and that of course returns bool. — jessehouwing
– jessehouwing, Commented Feb 13, 2012 at 20:43

jessehouwing · Accepted Answer · 2012-02-13 21:51:24Z

Without access to your DBContext it's hard to give you an exact query, ignoring the inefficiency of the query you're using.

From what we have, I expect the following code gets pretty close to what you want, or at least should get you started:

        if (!String.IsNullOrWhiteSpace(txtCompanyName.Text))
        {
            var result = 
                decals.Where(
                    d => (
                        from c in db.CT_Companies 
                            where c.CompanyName.Contains(txtCompanyName.Text.Trim()) 
                            select c.CompanyID
                    ).Contains(
                        (from t in db.CT_Tanks where t.CargoTankID == d.TankID select t.CompanyID).Single()));

I expect this will function exactly the same if you've setup your DBContext correctly:

        if (!String.IsNullOrWhiteSpace(txtCompanyName.Text))
        {
            IEnumerable<Decal> result = 
                decals.Where(d => string.Equals(d.Tank.Company.CompanyName, txtCompanyName.Text.Trim());

AlwaysAProgrammer · Accepted Answer · 2012-02-13 20:45:22Z

0

your problem is in the keyword function within the where clause.

You must write something like this .Where(d=>(....)). Please see 'jessehouwing' reply.

The syntax .Where(function(f) ....) is a VB.Net equivalent of the lambda expression in C#. The lambda expression .Where(d => (...)) means 'd' goes to (some action or expression ). Let me know if this helps.

answered Feb 13, 2012 at 20:45

AlwaysAProgrammer

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