Question about models with omit/nullable fields

[dankobg]

Hey thanks for this cool lib!
Just wanted to ask how you guys deal with creates or updates from a model or manually?

Ofc i can create my own "omit" pkg with that neat map trick (what oapi-codegen is doing with its nullable pkg...) and pass it to every repo func to do stuff if explicit null was provided or if value was unspecified, but could it be generated by this library?
Something like what go bob sql builder is doing, they create one "read" model and one "setter' with those omit/nullable fields.

I guess i could just modify the fields of the existing model in the code gen like in #360, but i still think it would be better to have those two separate, what do you think in general?

[houten11]

I'm not sure what you mean. Do you want to generate insert/update queries depending on model fields?

[dankobg]

For example i want to do a patch request and then update only fields that are specified (valid values or explicit nil provided) and ignore unspecified fields.

// generated model
type Post struct {
	ID        int32 `sql:"primary_key"`
	Name      string
	Desc      *string
	Draft     *bool
	CreatedAt time.Time
	UpdatedAt time.Time
}

func ptr[V any](v V) *V { return &v }

// Manually created or i could generate it... 
type PostSetter struct {
	Name  omit.Val[string] `json:"name,omitempty"`
	Desc  omit.Val[string] `json:"desc,omitempty"`
	Draft omit.Val[bool]   `json:"draft,omitempty"`
}

func (ps PostSetter) Patch() (p.ColumnList, model.Post) {
	var cols p.ColumnList
	var post model.Post

	cols = append(cols, t.Post.UpdatedAt)
	post.UpdatedAt = time.Now()

	if ps.Name.IsSpecified() {
		cols = append(cols, t.Post.Name)
		if !ps.Name.IsNull() {
			post.Name = ps.Name.MustGet()
		}
	}
	if ps.Desc.IsSpecified() {
		cols = append(cols, t.Post.Desc)
		if !ps.Desc.IsNull() {
			post.Desc = ptr(ps.Desc.MustGet())
		}
	}
	if ps.Draft.IsSpecified() {
		cols = append(cols, t.Post.Draft)
		if !ps.Draft.IsNull() {
			post.Draft = ptr(ps.Draft.MustGet())
		}
	}
	return cols, post
}

And then i can update like this:

func UpdatePost(ctx context.Context, db *sql.DB, postID int64, in PostSetter) {
	cols, m := in.Patch()

	q := t.Post.UPDATE(cols).
		MODEL(m).
		WHERE(t.Post.ID.EQ(p.Int(postID))).
		RETURNING(t.Post.AllColumns)

	var dest model.Post
	if err := q.QueryContext(ctx, db, &dest); err != nil {
		fmt.Println("failed:", err.Error())
	}

	b, _ := json.MarshalIndent(&dest, "", "  ")
	fmt.Printf("%+v\n\n %+v\n", q.DebugSql(), string(b))
}

Basically i have to keep in sync this second model with generated one.
It would be nice if the generator could be modified so i could lets say generate this "setter" model alongside normal model. Currently i can only change existing fields on the model but i couldn't find a way to add additional stuff next to it.
Here is that link from bob sql https://bob.stephenafamo.com/docs/models/table

[houten11]

Aha, I see. I think you can make Patch method more generic using reflection. Something like:

type Optional interface {
	IsSpecified() bool
	IsNil() bool
	MustGet() any
}

func Patch[T any](patch any, allColumns ColumnList) (ColumnList, T) {
	var columnsToUpdate ColumnList
	var modelToUpdate T

	patchValue := reflect.ValueOf(patch)
	modelValue := reflect.ValueOf(modelToUpdate)

	for i := 0; i < patchValue.NumField(); i++ {
		fieldValue := patchValue.Field(i)

		field := fieldValue.Interface().(Optional)

		if field.IsSpecified() {
			columnsToUpdate = append(columnsToUpdate, allColumns[i])

			if !field.IsNil() {
				modelValue.Field(i).Set(reflect.ValueOf(field.MustGet()))
			}
		}
	}

	return columnsToUpdate, modelToUpdate
}

Then you can call it for any table update:

func UpdatePost(ctx context.Context, db *sql.DB, postID int64, in PostSetter) {
	cols, m := Patch[model.Post](in, Post.AllColumns)

	q := t.Post.UPDATE(cols).
		MODEL(m).
		WHERE(t.Post.ID.EQ(p.Int(postID))).
		RETURNING(t.Post.AllColumns)

	var dest model.Post
	if err := q.QueryContext(ctx, db, &dest); err != nil {
		fmt.Println("failed:", err.Error())
	}
}

Then, to generate patch models (PostSetter), you can add another jet generator call, with your optional field type customization. Check generator customization.