gofasta g relation

Wires a GORM association between two resources. Patches the parent model with the appropriate fields and tags, and for belongs_to additionally emits a paired migration that adds the FK column + constraint on the parent’s table.

Bidirectional navigation requires running g relation twice (once per side) — the generator intentionally never assumes both sides need patching, since that’s a product decision (you may want one-way navigation only).

Usage

gofasta g relation <Resource> <kind> <Other> [flags]

<kind> is one of belongs_to, has_many, has_one.

Flags

Relation kinds

The FK direction is what determines whether a migration is emitted. belongs_to puts the FK column on this resource’s table, so this resource owns the schema change. has_many / has_one mean the FK lives on the other resource’s table — run g relation belongs_to <This> on the other side to actually create that column.

Examples

Belongs-to (with migration)

gofasta g relation Order belongs_to Customer

Patches app/models/order.model.go:

type Order struct {
    // ... existing fields ...
    CustomerID uuid.UUID `gorm:"type:uuid;not null"`
    Customer   *Customer `gorm:"foreignKey:CustomerID"`
}

Adds github.com/google/uuid import if not already present. Emits the migration:

-- db/migrations/NNNNNN_add_customer_id_to_orders.up.sql
ALTER TABLE orders ADD COLUMN customer_id uuid NOT NULL;
ALTER TABLE orders ADD CONSTRAINT fk_orders_customer_id FOREIGN KEY (customer_id) REFERENCES customers (id);

-- db/migrations/NNNNNN_add_customer_id_to_orders.down.sql
ALTER TABLE orders DROP CONSTRAINT fk_orders_customer_id;
ALTER TABLE orders DROP COLUMN customer_id;

Has-many (no migration)

gofasta g relation Customer has_many Order

Patches app/models/customer.model.go:

type Customer struct {
    // ... existing fields ...
    Orders []Order
}

No migration — the FK already lives on orders.customer_id. To complete the relation, run the matching belongs_to on the other side first.

Has-one (no migration)

gofasta g relation User has_one Profile

Patches app/models/user.model.go:

type User struct {
    // ... existing fields ...
    Profile *Profile
}

Bidirectional navigation

To make both sides able to traverse the relationship, run two commands:

gofasta g relation Order belongs_to Customer    # FK on orders, ord.Customer / ord.CustomerID
gofasta g relation Customer has_many Order      # cust.Orders

The two runs produce a coherent GORM mapping with no extra wiring needed.

Preview without writing

gofasta g relation Order belongs_to Customer --dry-run

Naming conventions

The FK migration always uses <table>_id as the column name and fk_<parent_table>_<column> as the constraint name.

Idempotency

The model patch checks each field individually — if the model already has CustomerID, that one field is skipped (no error). The migration filename includes a fresh version prefix, so re-running emits a duplicate migration (delete the old one if you don’t want to apply it twice).

Error codes