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#1788 ✓wontfix
Luke Burton

Telling ActiveRecord::ConnectionAdapters::SchemaStatements#create_table to not create a primary key isn't effective if you manually create an id column

Reported by Luke Burton | January 22nd, 2009 @ 06:42 AM | in 2.x

The situation

I want an "id" column, but I don't want it to be a primary key, and I want full control over its population.

Steps to reproduce

create_table :people, :id => false do |t|
      t.integer :id

>> Person.primary_key
=> "id"

Problem #1 - Person should not have any primary key, clearly, from the schema dump:

CREATE TABLE "people" ("id" integer, "created_at" datetime, "updated_at" datetime);

That leads to Problem #2:

>> Person.create(:id => 123)
=> #<Person id: 1, created_at: "2009-01-22 06:31:43", updated_at: "2009-01-22 06:31:43">

Using constructor syntax #create or #new, #attributes_from_column_definition is used and the "id" column is filtered out because it's thought of (incorrectly) as the primary key.

If you use the block creation syntax like:

person = do |p| = 123

Then you get id correctly set to 123. So the behavior is inconsistent.


If possible, ActiveRecord should not consider a column as being a primary key unless the DB layer says so. Currently it falls back on the string "id".

I'm not sure if you can "set_primary_key null" in the ActiveRecord model, but that might be a valid workaround if we can't rely on the DB layer. In the case of a workaround, it should be documented alongside AR::CA::SS#create_table to let people know they should explicitly set the primary key to null (or whatever) if they expect to use a column called "id".

Comments and changes to this ticket

  • rdavila

    rdavila April 18th, 2010 @ 10:05 PM

    Rails has many conventions and I think that this is one of these. You can't use the id column if it isn't a primary key, but you can setup a distinct primary through the set_primary_key class method. In my opinion if there is and id column and it isn't a primary key it's a problem with the table design.

  • Jeremy Kemper

    Jeremy Kemper April 24th, 2010 @ 10:10 PM

    • State changed from “new” to “wontfix”

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