Hi.
This must be the most obvious thing to do, but I just can't seem
to
find examples of how to do this. I would like to create a table
with a
table unique constraint on database level.
In deed some migration code that would generate the following SQL
CREATE TABLE properties (
namespace CHAR(50),
name CHAR(50),
value VARCHAR(100),
CONSTRAINT my_constraint UNIQUE (namespace, name)
);
create_table :properties.....
.....
end
add_index :properties, [:namespace, :name], :unique => true
After trying this and opening my interactive SQL prompt (psql), I
can
see that this only creates an index on the table not a table
constraint. I can still put duplicate rows in the table.
Hrm. I can't... Rails 2.3.5, Postgresql 8.4.1 (on mac, but doubt
that matters)
I am so sorry. I did't do exactly as you said, explanation:
I used
create_table :properties do |t|
.....
t.index [:namespace, :name], :unique => true
end
That does NOT create an index!!! and therefore neither a constraint!!!
I gues that is a bug in the PostgreSQL adapter.
But when I do as you describe using add_index syntax instead it will
create an index (AND constraint!)
But the fact that 't.index [:namespace, :name], :unique => true' does
not generate an index is a bug, right?
Thanks for all help. I appreciate the time you've spent on this.
That does indeed look like a bug. I just tried it and it doesn't
work. What's strange is the source code seems to say that "t.index"
simply calls "add_index" just like if I'd done it normally.
I just tried it using MySQL as the backend and it does NOT work either.
+------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| a | varchar(255) | YES | | NULL | |
| b | varchar(255) | YES | | NULL | |
| created_at | datetime | YES | | NULL | |
| updated_at | datetime | YES | | NULL | |
+------------+--------------+------+-----+---------+----------------+
So, at least it's not a postgresql specific bug.
You should submit a ticket to the Rails folks...
-philip
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