Creating Site column with a custom SPFieldType

Question

i have this solution deployed on my sharepoint.

http://ilovesharepoint.codeplex.com/releases/view/44989

And i created a Site column of type Lookup with picker that is from the above solution. Everything works good, the problem is when i try to create the field using code i cannot seem to find a way.

Right now i have the site column create but before i do any opperation on the list item i want to check if it has the column of type lookup with picker if so proceed and if not create it.

Here is what i got so far.

if (parentSite.Fields.TryGetFieldByStaticName("TestColumn") == null)
{

    parentSite.Fields.Add("TestColumn", !myCustomType!, true);
    parentSite.Update();
}

Help :'(

Answer 1

So, it took me over 1 hour fighting with this, however it isn't fully solved. Firstly, you are working with Lookup. These fields are really pain...

You cannot so simply add a lookup field to site, also, from my personal experience - lookups as site fields are not a good solution. SPFieldCollection has overloaded method Add(), which require only SPField. However, this one didn't work correctly for me.

Retrieving custom field, easy way: Just add reference to LookupFieldWithPicker.dll, you can find it in the wsp package. Retrieving custom field using Reflection:

var assembly = Assembly.Load("iLoveSharePoint.Fields.LookupFieldWithPicker, Version=14.0.0.0, Culture=neutral, PublicKeyToken=3443098eba475529");
var fieldType = assembly.GetTypes().FirstOrDefault(type => type.Name == "LookupFieldWithPicker");
// just use SPFieldLookup constructors, below overload nr 3
var field = Activator.CreateInstance(fieldType, web.Fields, fieldType.Name, "instanceName") as SPFieldLookup;

From now, you must create lookup using AddLookup method, because other one fails.

// throws: SPException: 'Use AddLookup instead'. Nice to know... 
//var name = web.Fields.Add("webLookupName", SPFieldType.Lookup, true);

var name = web.Fields.AddLookup("webLookupName", list.ID, true);
web.Update();

// redundant, just checking if field exist
var test = web.Fields.TryGetFieldByStaticName(name);

var field = new LookupFieldWithPicker(web.Fields, name);
field.StaticName = "IhaveChangedYourName";
field.Update();

// probably redudant
web.Update();

I finished on this. It is adding correctly lookup AND set staticName to "Ihave(...)" (check it with sharepoint manager). However, it is not changing the field type correctly. Potencial solution to resolve this problem? Check this blog. Just modify the field XML. Should work, however this is brute force.

Cheers.