Question

有人用复合主键成功创建到表的关系吗？我正在努力实现以下目标：

create table(:resources, primary_key: false) do
  add :id, :uuid, primary_key: true
  add :version, :id, primary_key: true 
  # ... other details about the resource
end

create table (:resource_instances, primary_key: false) do
  add :id, :uuid, primary_key: true
  add :resource_id,
      references(:resources, type: :uuid, column: :id),
      null: false

  add :resource_version,
      references(:resources, type: :id, column: :version),
      null: false
  # ... specific details about this instance of the resource
end

运行迁移会生成以下日志：

11:24:00.100 [info]  create table my_schema.resources

11:24:00.152 [info]  create table my_schema.resource_instances
** (Postgrex.Error) ERROR 42830 (invalid_foreign_key) there is no unique constraint matching given keys for referenced table "resources"
    (ecto_sql) lib/ecto/adapters/sql.ex:629: Ecto.Adapters.SQL.raise_sql_call_error/1
    (elixir) lib/enum.ex:1336: Enum."-map/2-lists^map/1-0-"/2
    (ecto_sql) lib/ecto/adapters/sql.ex:716: Ecto.Adapters.SQL.execute_ddl/4
    (ecto_sql) lib/ecto/migration/runner.ex:343: Ecto.Migration.Runner.log_and_execute_ddl/3
    (ecto_sql) lib/ecto/migration/runner.ex:117: anonymous fn/6 in Ecto.Migration.Runner.flush/0
    (elixir) lib/enum.ex:1948: Enum."-reduce/3-lists^foldl/2-0-"/3
    (ecto_sql) lib/ecto/migration/runner.ex:116: Ecto.Migration.Runner.flush/0
    (stdlib) timer.erl:166: :timer.tc/1
    (ecto_sql) lib/ecto/migration/runner.ex:25: Ecto.Migration.Runner.run/7
    (ecto_sql) lib/ecto/migrator.ex:342: Ecto.Migrator.attempt/7
    (ecto_sql) lib/ecto/migrator.ex:243: anonymous fn/4 in Ecto.Migrator.do_up/4
    (ecto_sql) lib/ecto/migrator.ex:324: anonymous fn/3 in Ecto.Migrator.run_maybe_in_transaction/6
    (ecto_sql) lib/ecto/adapters/sql.ex:898: anonymous fn/3 in Ecto.Adapters.SQL.checkout_or_transaction/4
    (db_connection) lib/db_connection.ex:1415: DBConnection.run_transaction/4
    (ecto_sql) lib/ecto/migrator.ex:323: Ecto.Migrator.run_maybe_in_transaction/6
    (elixir) lib/task/supervised.ex:90: Task.Supervised.invoke_mfa/2
    (elixir) lib/task/supervised.ex:35: Task.Supervised.reply/5
    (stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3

Answer 1

尝试一下：

    create table(:resources, primary_key: false) do
        add :id, :uuid, primary_key: true
        add :version, :id, primary_key: true, auto_generate: true
    end
    create unique_index(:resources, [:id])
    create unique_index(:resources, [:version])

    create table(:resource_instances, primary_key: false) do
        add :resource_id,
            references(:resources, type: :uuid, column: :id),
            null: false
        add :resource_version,
            references(:resources, type: :id, column: :version),
            null: false
    end

由于创建复合键，您似乎还需要创建单独的唯一索引才能引用那些因此基本上为各个列添加了unique_indices

Elixir-Ecto-复合主键和关系

1 个答案: