Rails - Dec 2006 - acts_as_nested_set first record foreign key error

I’m trying to use nested set. When I try to insert the first row with a
parent_id of 0 I get an error because of the foreign key constraint on
parent_id failing.
Obviously the parent_id can’t be 0 if there is no row with an id of 0,
but nested_set REQUIRES that the parent_id of a root be 0. So, I thought
maybe (since the documentation is lacking) that I don’t need the
constraint on parent_id, so I removed it and it did not work at all when
I inserted child objects. So, how do I get the first row inserted with a
parent_id of 0?

Thanks.
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Man, this is confusing...

I can make things work (sort of) by doing the following:

1. I keep the constraint on parent_id and set the root parent_id to null 
instead of 0. (Just like with acts_as_tree)

2.  I create the first record (from the console) which is the root:
<code>root = Model.create("attributes" =>
"attributes")</code>

3. Then I create the second record:
<code>child1 = Model.create("attributes" =>
"attributes")</code>

4. Then I set child1 as a child of the root:
<code>root.add_child(child1)</code>

5.  Then I check the database and the lft and rgt values are not 
correct.  They show as:
<code>
id     parent_id     lft     rgt
1      NULL           0      2
2     1                 0      1
</code>
6. Obviously this is not correct, so I manually change the values in the 
database to the following:
<code>
id     parent_id     lft     rgt
1      NULL           1      4
2     1                 2      3
</code>
7.  Then I add all the children, grand children etc.....
<code>
subchild1 = Model.create("attributes" => "attributes")
child1.add_child(subchild1)
child2 = Model.create("attributes" => "attributes")
root.add_child(child2)
subchild2 = Model.create("attributes" => "attributes")
child2.add_child(subchild2)
etc...
</code>

All of the other children and grand children are created successfully 
and the lft and rgt values are updated accordingly and correctly.

So, the question remains.....why can''t I create the first records 
correctly?  Also, how do I create additional roots and their children 
without manually updating the lft and rgt values?


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(Sorry about the <code> tags, they work in a different forum where
I''m
asking the question and I copy/pasted from there...my bad.)

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