Get the InternalFieldName Programmatically

Question

I have a requirement to always use the internal field name for columns in custom Visual Studio projects. I want to use the internal string value of the field name consistently and have the following two methods defined.

An example of how and when I need to use the internal field name is as follows:

properties.ListItem["My Field Name"] = "";

In place of "My Field Name" I always want to use the internal field name. In lots of instances site collection owners will rename fields from "MyOriginalInternalFieldName" to "My Field Name", for example. The code above still needs to work.

Are the below methods the best way to always use the internal field name string value?

(NOTE: I found them here: http://apicollection.wikia.com/wiki/Get_And_Set_Value_By_Field_Internal_Name )

        public object GetValueInternalName(SPListItem item, string fieldInternalName)
    {
        if (item == null)
            throw new ArgumentNullException("item");

        if (item.Fields.ContainsField(fieldInternalName))
        {
            SPField field = item.Fields.GetFieldByInternalName(fieldInternalName);
            if (item[field.Id] != null || string.IsNullOrEmpty(field.DefaultValue))
                return item[field.Id];
            else if (field.FieldValueType == typeof(Boolean))
                return bool.Parse((field.DefaultValue == "0") ? bool.FalseString : bool.TrueString);
            else
                return Convert.ChangeType((field.DefaultValueTyped != null) ? field.DefaultValueTyped : field.DefaultValue, field.FieldValueType);
        }

        return null;
    }

    public void SetValueInternalName(SPListItem item, string fieldInternalName, object value)
    {
        SPField field = item.Fields.GetFieldByInternalName(fieldInternalName);
        if (value is DateTime && (DateTime)value == DateTime.MinValue)
            item[field.Id] = null;
        else
            item[field.Id] = value;
    }

Is there a way I could include a custom "utilities" class that I could reuse across projects so that I don't have to put these two methods in multiple times into the classes where I need to use them?

Answer 1

You seem to have a chicken and egg problem. If you are trying to access a field via its name, but don't know what the name is, you need to somehow determine its name. You might try iterating the fields on the list item until you get the one you're looking for, but the question remains, how do you know which is the right one? (That approach will also have performance implications as well.) Bottom line, we use internal names because they are consistent and unchangeable, but in your case they seem not to be (at least from instance to instance), so you lose the benefits.

The method definitions you posted are not quite what I would write but if they work for you, they should do fine.

Finally, to answer your final question, you can make those methods reusable across projects by putting them in a separate project of type "Class Library". Just add a reference to the DLL from that project into any projects that consume it.