Question

I got it working with adding it to a specified list, but I want to go trough all lists in the site collection. I just cant find out whats making this not work.

Code that works for one list:

    void btnAdd_Click(object sender, EventArgs e)
    {
        try
        {
            using (SPSite site = new SPSite("http://asdf:150/sites/test"))
            {
                using (SPWeb web = site.OpenWeb())
                {
                    SPList list = web.Lists["test8"];

                    //Needed?
                    site.AllowUnsafeUpdates = true;
                    web.AllowUnsafeUpdates = true;

                    string mainLocation = list.Fields.Add("New Field", SPFieldType.Text, false, false, null);
                    readOnly(list, mainLocation);

                    //Add to default view (will be removed after testing)
                    SPView view = list.DefaultView;
                    defaultView(view, "New Field");
                }
            } 
        }
        catch (Exception ex)
        {
        }
    }

I want to add the field to all lists in the site collection, but I dont know what I could be doing wrong, this is what I have so far.

void btnAdd_Click(object sender, EventArgs e)
        {
            using (SPSite site = new SPSite("http://asdf:150/sites/test"))
            {
                using (SPWeb web = site.OpenWeb())
                {
                    //Needed?
                    site.AllowUnsafeUpdates = true;
                    web.AllowUnsafeUpdates = true;
                    try
                    {
                        SPListCollection lists = web.Lists; // ??
                        foreach (SPList list in lists)
                        {
                            string mainLocation = list.Fields.Add("New Field", SPFieldType.Text, false, false, null);
                            readOnly(list, mainLocation);

                            //Add to default view (will be removed after testing)
                            SPView view = list.DefaultView;
                            defaultView(view, "New Field");
                        }
                    }
                    catch (Exception)
                    {
                        // some exception handling
                    }
                    finally
                    {
                        //web.Dispose();
                    }
                }
            }
        }

Helper methods

void readOnly(SPList list, string name)
{
    SPField listField = list.Fields.GetFieldByInternalName(name);
    listField.ReadOnlyField = true;
    listField.Update();
}

void defaultView(SPView view, string field)
{
    view.ViewFields.Add(field);
    view.Update();
}

Hope any any one of you are smarter then me here 🙂

Answer 1

I run your code and you have 2 main problems.
1. Default view can bu null in some lists. So you should check it.

SPView view = list.DefaultView;
if(view != null)
{
    defaultView(view, "New Field");
}

2. SPListCollection is modified, when you make changes to list. You should have
temporary IEnumerable for iterating through lists.

using System.Linq;

SPListCollection listCollection = web.Lists;
IEnumerable<SPList> lists = listCollection.Cast<SPList>();
foreach (SPList list in lists)
{

3. Do not ignore Excaptions. Add some code to catch block, that can help you.

catch (Exception ex)
{
    Console.WriteLine(ex.ToString());
}