Partial Updates

Every generated resource exposes both a full replacement and a partial update:

PATCH is not a relaxed PUT. Its generated input fields are pointers, so the server can distinguish a missing property from a deliberate zero value.

type BookPatch struct {
	Title     *string  `json:"title" validate:"omitempty,required,max=200"`
	Price     *float64 `json:"price" validate:"omitempty,min=0"`
	Published *bool    `json:"published"`
}

For a book whose title is "A Wizard of Earthsea" and published is true:

PATCH /books/7
Content-Type: application/json

{"published": false}

sets published to false and leaves the title unchanged. Likewise, {"price": 0} writes zero rather than being mistaken for an absent value.

The existing validate:"..." rule is applied only when that PATCH property is supplied. Validation, error mapping, transactions, route auth, strict auth, and generated OpenAPI all apply to PATCH in the same way they do to PUT.

Hooks and overrides

Implement BeforePatchHook on a resource wrapper to validate or adjust the pointer-shaped input before it is written:

func (r *bookResource) BeforePatch(ctx context.Context, in *api.BookPatch) error {
	if in.Title != nil {
		*in.Title = strings.TrimSpace(*in.Title)
	}
	return nil
}

BeforePatchHook runs inside the same transaction as Patch. To replace the operation itself, implement Patch(ctx, id, in) on the wrapper; its method set is separate from the existing CRUD override interface, so adding PATCH does not disrupt existing List, Retrieve, Create, Update, or Delete overrides.