Foreign key constraint sql error from entries/saveEntry when adding entry I am getting a foreign key constraint sql error when trying to add an entry through a front end form.

&lt;form method="post" accept-charset="UTF-8"&gt;
  {{ getCsrfInput() }}
  &lt;input type="hidden" name="action" value="entries/saveEntry"&gt;
  &lt;input type="hidden" name="entryId" value="{{ entry.id }}"&gt;
  &lt;select name="fields[vendor][]"&gt;
    {% for v in craft.entries.section('vendors') %}
      &lt;option value="v.id"&gt;{{v.title}}&lt;/option&gt;
    {% endfor %}
  &lt;/select&gt;
  &lt;input type="submit" value="Submit"/&gt;
&lt;/form&gt;


vendor is an Entries fieldtype, for unlimited entries from the vendors channel. Very similar code for adding a category works fine.

The error (complete with back-ticks):


  CDbCommand failed to execute the SQL statement: SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (metro.craft_relations, CONSTRAINT craft_relations_targetId_fk FOREIGN KEY (targetId) REFERENCES craft_elements (id) ON DELETE CASCADE). The SQL statement executed was: INSERT INTO craft_relations (fieldId, sourceId, sourceLocale, targetId, sortOrder, dateCreated, dateUpdated, uid) VALUES (:row0_col0, :row0_col1, NULL, :row0_col3, :row0_col4, :row0_col5, :row0_col6, :row0_col7). Bound with :row0_col0='13', :row0_col1='39', :row0_col3='v.id', :row0_col4=1, :row0_col5='2016-02-13 08:28:03', :row0_col6='2016-02-13 08:28:03', :row0_col7='e455a06e-8f9d-4299-ad57-93577907f9a0'
I think the problem is this:

&lt;option value="v.id"&gt;{{v.title}}&lt;/option&gt;


Try changing it to:

&lt;option value="{{ v.id }}"&gt;{{v.title}}&lt;/option&gt;