Set Enforce Unique Values for Title Field in Custom List Definition

Question

I have custom content type, custom list definition from this content type, and list instance in my visual studio project. I could not set Enforce Unique Values for Title Field. How can I achieve this.

Here is what I did:

In custom content type, I included title field (Elements.xml):

<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
  <Field ID="{fa564e0f-0c70-4ab9-b863-0177e6ddd247}" Name="Title" Type="Text" Required="TRUE" EnforceUniqueValues="TRUE" Indexed="TRUE"  />  
 <!-- Parent ContentType: Item (0x01) -->
 <ContentType ...>
<FieldRefs>
  <FieldRef ID="{fa564e0f-0c70-4ab9-b863-0177e6ddd247}" Name="Title" />
</FieldRefs>
</ContentType>
</Elements>

Then in my custom list definition, I also included Title field (Schema.xml):

<ContentTypes>
  <ContentType ID="0x0100db7f2ee33f6f48efaac128f9e90eafd3" Name="..." Group="Micts Content Types" Description="..." Inherits="TRUE" Version="0">
    <FieldRefs>
      <FieldRef ID="{fa564e0f-0c70-4ab9-b863-0177e6ddd247}" Name="Title" />
    </FieldRefs>
  </ContentType>
</ContentTypes>
<Fields>
  <Field ID="{fa564e0f-0c70-4ab9-b863-0177e6ddd247}" Name="Title" Type="Text" Required="TRUE" EnforceUniqueValues="TRUE" Indexed="TRUE"  />
</Fields>

Answer 1

If "Title" is a custom field then you can override Validate method for your field type, or you can add a event receiver to your list. A similar question is explaining every possible way.

You can also try CodePlex

Hope it helps