使用 peewee 的唯一共同约束

Question

Is it way to apply unique by two columns constraint to model using peewee. There are raw way (using SQL() ) but I'm finding another.

Updated:

I'm using postgres so I tried to do like @booshong says below then in raw SQL I gave the following (for simplicity transaction related BEGIN and COMMIT omitted and output was intended):

CREATE TABLE IF NOT EXISTS "foo" (
    "id" SERIAL NOT NULL PRIMARY KEY,
    "field_1" VARCHAR(255) NOT NULL,
    "field_2" VARCHAR(255) NOT NULL);

CREATE UNIQUE INDEX IF NOT EXISTS "foo_field_1_field_2" 
    ON "foo" ("field_1", "field_2");

CREATE TABLE IF NOT EXISTS "foo2" (
    "id" SERIAL NOT NULL PRIMARY KEY,
    "field_1" VARCHAR(255) NOT NULL,
    "field_2" VARCHAR(255) NOT NULL, 
    UNIQUE (field_1, field_2));

And as we can see it's different things as I say earlier.

Answer 1

class Foo(BaseModel):
    field_1 = CharField()
    field_2 = CharField()

    class Meta:
        indexes = (
            (('field_1', 'field_2'), True),
        )


class Foo2(BaseModel):
    field_1 = CharField()
    field_2 = CharField()

    class Meta:
        constraints = [SQL('UNIQUE (field_1, field_2)')]


Foo.create_table()
Foo2.create_table()

-- MySQL v8

show create table foo;
>> CREATE TABLE `foo` (
  `id` int NOT NULL AUTO_INCREMENT,
  `field_1` varchar(255) NOT NULL,
  `field_2` varchar(255) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `foo_field_1_field_2` (`field_1`,`field_2`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci


show create table foo2;
>> CREATE TABLE `foo2` (
  `id` int NOT NULL AUTO_INCREMENT,
  `field_1` varchar(255) NOT NULL,
  `field_2` varchar(255) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `field_1` (`field_1`,`field_2`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

The two tables are equivalent.