Solving drupal database entry dependancy problem?

Question

In Drupal, if you want to insert something into the node table, 'nid' can be null, but 'vid' can't. The inverse is true for the node_revision table.

So my question is, in what order are inserts done to the Drupal db when a node is created?

i.e. I can't insert into the node table, because I don't have the VID, and I can't insert into the node_revision table, because I don't have a nid.

Also, is there some kind of function available that can easily do this insert for you?

Answer 1

The code of the node_save function is available ; did you try to see how it's working ?

Here's the part that relates to node creation :

if ($node->is_new) {
  _node_save_revision($node, $user->uid);
  drupal_write_record('node', $node);
  db_query('UPDATE {node_revisions} SET nid = %d WHERE vid = %d', $node->nid, $node->vid);
  $op = 'insert';
}

Apparently, it first saves the revision of the node, and, only then, saves the node itself.

After that, the node_revisions record is updated, to put the value of the nid.

If you want t save a node, you shouldn't write code that would do that for you : you just have to call node_save, and it'll save the node, call the required hooks, and all that.