Integrity constraint violation – yii\db\IntegrityException

[hezhijia]

SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'access_token' cannot be null
The SQL being executed was: INSERT INTO wechat (name, description, created_at, updated_at, access_token) VALUES ('test', 'test', 1465804363, 1465804363, NULL)

access_token要在哪设置的？？？