Associated id is save automatically?

[manicar2093]

Hi!.

I'm having a little problem to save an associated id. I don't know if I'm doing it well. Let me explain what it is happen to me.

I have this db struct:

-- authors definition

CREATE TABLE authors (
	id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
	name TEXT
);

-- books definition

CREATE TABLE books (
	id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
	title TEXT,
	category TEXT,
	price INTEGER,
	discount NUMERIC,
	stock INTEGER,
	author_id INTEGER NOT NULL,
	FOREIGN KEY(author_id) REFERENCES authors(id)
);

These are my go models:

type Author struct {
	ID   int32
	Name string
}

type Book struct {
	ID       int32
	Title    string
	Category string
	Price    int
	Discount bool
	Stock    int
	Author   Author `ref:"author_id" fk:"id" autosave:"true"`
	AuthorID int32
}

I want to save an Author instance and pass it to a Book instance. I was expecting that the relation would save AuthorID automatically but no. It shows this error:

panic: ForeignKeyConstraintError: rel: inconsistent belongs to ref and fk

This is the code I'm running:

const dbPath = "./go-rel-example.db"

func main() {
	adapter, err := sqlite3.Open(dbPath)
	if err != nil {
		panic(err)
	}

	defer adapter.Close()

	repo := rel.New(adapter)

	err = Example(context.Background(), repo)
	if err != nil {
		panic(err)
	}

}

func Example(ctx context.Context, repo rel.Repository) error {

	return repo.Transaction(ctx, func(ctx context.Context) error {
		author := Author{
			Name: "Anne Paterson",
		}

		err := repo.Insert(ctx, &author)
		if err != nil {
			return err
		}
		log.Println(author)

		book := Book{
			Title:    "A new story",
			Category: "horror",
			Price:    10,
			Discount: false,
			Stock:    2,
			Author:   author,
		}
		err = repo.Insert(ctx, &book)
		if err != nil {
			return err
		}

		log.Println(book)

		log.Println("-----DONE-----")

		return nil
	})

}

Now my questing here is if this can be done. I don have any problem to pass the id to the association, but I thing would be great to pass the saved instance and rel takes the associated id to save it.

Thanks!!! 🏆 REL is awesome! 😃

[Fs02]

Hi, thanks for using REL and reporting this,

Currently REL checks if foreign and association key have the same key to prevent modifying association of other records.

rel/filter_query.go

Lines 636 to 651 in 9969cea

	func filterBelongsTo(assoc Association) (FilterQuery, error) {
	var (
	rValue = assoc.ReferenceValue()
	fValue = assoc.ForeignValue()
	filter = Eq(assoc.ForeignField(), fValue)
	)
	if rValue != fValue {
	return filter, ConstraintError{
	Key: assoc.ReferenceField(),
	Type: ForeignKeyConstraint,
	Err: errors.New("rel: inconsistent belongs to ref and fk"),
	}
	}
	return filter, nil

but I think it's make sense to support your case for belongs to, we can set the reference value if it's a zero value around here:

rel/repository.go

Lines 558 to 567 in 9969cea

	if loaded {
	filter, err := filterBelongsTo(assoc)
	if err != nil {
	return err
	}
	if err := r.update(cw, assocDoc, assocMut, filter); err != nil {
	return err
	}
	} else {

let me know if you are interested to submit fix for this, Thank you

[manicar2093]

Hi! Thank for your answer.

Let me give it a check and I send my PR. :D

[Fs02]

Thank you, let me know if you have any question!