在PostGres中插入NULL值后，如何自动生成ID？

Question

I'm using PostGres 9.5. I have the following set up in my table, in hopes of auto-generating IDs …

myproject=> \d my_object_times
                               Table "public.my_object_times"
      Column       |            Type             |              Modifiers              
-------------------+-----------------------------+-------------------------------------
…
 time_in_ms        | bigint                      | 
 created_at        | timestamp without time zone | not null
 updated_at        | timestamp without time zone | not null
 name              | character varying           | 
 age               | integer                     | 
 city              | character varying           | 
 state_id          | integer                     | 
 country_id        | integer                     | 
 overall_rank      | integer                     | 
 age_group_rank    | integer                     | 
 gender_rank       | integer                     | 
 races_id          | integer                     | 
 event_id          | character varying           | 
 id                | character varying           | not null default uuid_generate_v4()

But when I try and run a bulk insert statement, the content of which looks something like

INSERT INTO "my_object_times" ("first_name","last_name","time_in_ms","created_at","updated_at","name","participant","age","city","state_id","country_id","overall_rank","age_group_rank","gender_rank","races_id","event_id","id","division_low_age","division_high_age") VALUES (NULL,NULL,1403000,'2016-10-12 15:36:42.766936','2016-10-12 15:36:42.767104','Terry Williamson',NULL,NULL,NULL,NULL,NULL,4,1,NULL,NULL,'0bf8c3bc-3577-4cab-bdd4-61e64655eaed',NULL,3,3),(NULL,NULL,1431000,'2016-10-12 15:36:42.766936','2016-10-12 15:36:42.767104','Casey Reinl',NULL,NULL,NULL,NULL,NULL,5,1,NULL,NULL,'0bf8c3bc-3577-4cab-bdd4-61e64655eaed',NULL,2,2),(NULL,NULL,1473000,'2016-10-12 15:36:42.766936

I get an error

Error during processing: PG::NotNullViolation: ERROR:  null value in column "id" violates not-null constraint
DETAIL:  Failing row contains (null, null, 1403000, 2016-10-12 15:36:42.766936, 2016-10-12 15:36:42.767104, Terry Williamson, null, null, null, null, null, 4, 1, null, null, 0bf8c3bc-3577-4cab-bdd4-61e64655eaed, null, 3, 3).

The SQL is being auto generated by the Rails 4.2.7 activerecord-import gem, which I'm invoking like so

MyObjectTime.import inserts

How do I get my IDs auto-generated for me if none is supplied?

Answer 1

Try this,

columns_without_id = YourModel.column_names.reject { |column| column == 'id' }
import(columns_without_id, records)

Ref: Github issue