Null value in column error when sending row data that has a field set to None

[jsoneaday]

I have this table schema. The field secondary_lang_id is nullable, when I send data to insert that is None for that field I get the error listed below. I thought nullable foreign key relationships are allowed in postgres?

create table job (
    "id" bigserial primary key,
    "created_at" timestamptz(3) not null default current_timestamp,
    "updated_at" timestamptz(3) not null default current_timestamp,
    "employer_id" bigserial not null,
    "title" varchar(60) not null,
    "description" varchar(2500) not null,
    "is_remote" boolean not null,
    "primary_lang_id" bigserial not null,
    "secondary_lang_id" bigserial,
    "industry_id" bigserial not null,
    "salary_id" bigserial not null,

    constraint fk_employer foreign key(employer_id) references employer(id),
    constraint fk_primary_lang foreign key(primary_lang_id) references prog_language(id),
    constraint fk_secondary_lang foreign key(secondary_lang_id) references prog_language(id),
    constraint fk_industry foreign key(industry_id) references industry(id),
    constraint fk_salary foreign key(salary_id) references salary(id)
);

Err(Database(PgDatabaseError { severity: Error, code: "23502", message: "null value in column \"secondary_lang_id\" of relation \"job\" violates not-null constraint", detail: Some("Failing row contains (378, 2024-07-01 18:33:56.635+00, 2024-07-01 18:33:56.635+00, 1, Senior C# Developer, \n About the job\n As a Senior Mobil..., f, 1, null, 1, 1)."), hint: None, position: None, where: None, schema: Some("public"), table: Some("job"), column: Some("secondary_lang_id"), data_type: None, constraint: None, file: Some("execMain.c"), line: Some(1883), routine: Some("ExecConstraints") }))

[CommanderStorm]

@jsoneaday sorry for the late answer, hope this helps you in any case ^^

Nullable foreign keys are allowed in postgres.
Though, you have not defined your table that way:
bigserial is meant for autoincremented id columns and it has default "not null" and creates one sequence.

=> The foreign key references for BIGSERIAL should use BIGINT

Further reading: https://stackoverflow.com/questions/55823485/foreign-key-bigserial-null-postgres