nullzero relations not being fetched

[kubakl]

When defining a nullzero relation it fails when using Scan().
Example:

type MainTable struct {
    ID int64 `bun:",pk,notnull`
    ChildID int64
    Child *Parent `bun:",rel:has-one,join:child_id=id"`
}

type Parent struct {
    ID int64 `bun:",pk,notnull"`
    ChildID int64 `bun:",nullzero"`
    Child *Child `bun:",rel:has-one,join:child_id=id"`
}

type Child struct {
    ID int64
    ...
}

With this structure when I try to fetch MainTable and add a relation using Relation("Child.Child") it rather returns no element even though it exists and can be fetched directly or panics with:

reflect: call of reflect.Value.Field on ptr Value

I found a similar issue here, not sure if it's related #799

[codeliger]

#943

If i understand correctly i have the same issue here.

[JunNishimura]

@kubakl

I have implemented it as you have shown as an example in the following way, but I could not reproduce the bug.

type Child struct {
	ID int `bun:"id,pk,notnull"`
}

type Parent struct {
	ID      int `bun:"id,pk,notnull"`
	ChildID int
	Child   *Child `bun:"rel:has-one,join:child_id=id"`
}

type Main struct {
	ID      int `bun:"id,pk,notnull"`
	ChildID int
	Child   *Parent `bun:"rel:has-one,join:child_id=id"`
}
func main() {
	...

	db := bun.NewDB(sqlDB, mysqldialect.New())

	db.AddQueryHook(bundebug.NewQueryHook(bundebug.WithVerbose(true)))

	ctx := context.Background()

	// Create tables
	if _, err := db.NewDropTable().Model((*Main)(nil)).IfExists().Exec(ctx); err != nil {
		log.Fatalf("create table failed: %v", err)
	}
	if _, err := db.NewDropTable().Model((*Parent)(nil)).IfExists().Exec(ctx); err != nil {
		log.Fatalf("create table failed: %v", err)
	}
	if _, err := db.NewDropTable().Model((*Child)(nil)).IfExists().Exec(ctx); err != nil {
		log.Fatalf("create table failed: %v", err)
	}
	if _, err := db.NewCreateTable().Model((*Child)(nil)).Exec(ctx); err != nil {
		log.Fatalf("create table failed: %v", err)
	}
	if _, err := db.NewCreateTable().Model((*Parent)(nil)).Exec(ctx); err != nil {
		log.Fatalf("create table failed: %v", err)
	}
	if _, err := db.NewCreateTable().Model((*Main)(nil)).Exec(ctx); err != nil {
		log.Fatalf("create table failed: %v", err)
	}
	// Insert data
	if _, err := db.NewInsert().Model(&Child{ID: 1}).Exec(ctx); err != nil {
		log.Fatalf("insert failed: %v", err)
	}
	if _, err := db.NewInsert().Model(&Parent{ID: 1, ChildID: 1}).Exec(ctx); err != nil {
		log.Fatalf("insert failed: %v", err)
	}
	if _, err := db.NewInsert().Model(&Main{ID: 1, ChildID: 1}).Exec(ctx); err != nil {
		log.Fatalf("insert failed: %v", err)
	}
	// Select data
	var main Main
	if err := db.NewSelect().Model(&main).Relation("Child.Child").Where("main.id = ?", 1).Scan(ctx); err != nil {
		log.Fatalf("select failed: %v", err)
	}
	log.Printf("%+v", main) // result: {ID:1 ChildID:1 Child:0xc00020c2a0}
}

Could you please tell me a bit more about under what conditions the bug occurred (which RDBMS, which version of Bun)?

[kubakl]

@JunNishimura I can see you're not checking it like the description specifies this happens when the ChildID in the Parent table has bun:",nullzero" specified. This doesn't work for me, I'm using postgres lib and I'm working on bun version v1.1.14

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. If there is no update within the next 7 days, this issue will be closed.

[kubakl]

@JunNishimura This is a big issue. From what I understand it's somehow related with this #377. I can see it hasn't been touched either...

[j2gg0s]

@kubakl

Could you provide an example of the usage that triggers the error? I couldn’t find the relevant code.
The following code runs successfully on both the latest version and v1.1.14.

package main

import (
	"context"
	"database/sql"
	"fmt"

	"github.com/uptrace/bun"
	"github.com/uptrace/bun/dialect/pgdialect"
	"github.com/uptrace/bun/driver/pgdriver"
	"github.com/uptrace/bun/extra/bundebug"
)

func main() {
	ctx := context.Background()

	sqldb := sql.OpenDB(pgdriver.NewConnector(pgdriver.WithDSN("postgres://bun:bun@localhost:5433/bun?sslmode=disable")))

	db := bun.NewDB(sqldb, pgdialect.New())
	db.AddQueryHook(bundebug.NewQueryHook(
		bundebug.WithVerbose(true),
		bundebug.FromEnv("BUNDEBUG"),
	))
	defer db.Close()

	if err := db.ResetModel(ctx, (*MainTable)(nil), (*Parent)(nil), (*Child)(nil)); err != nil {
		fmt.Println(err)
	}

	childs := []*Child{
		{ID: 1},
	}
	parents := []Parent{
		{ID: 1, ChildID: 1},
		{ID: 2, ChildID: 1},
		{ID: 3, ChildID: 2},
	}
	mainTables := []MainTable{
		{ID: 1, ChildID: 1},
		{ID: 2, ChildID: 2},
		{ID: 3, ChildID: 3},
	}

	db.NewInsert().Model(&childs).Exec(ctx)
	db.NewInsert().Model(&parents).Exec(ctx)
	db.NewInsert().Model(&mainTables).Exec(ctx)

	// query

	ts := []MainTable{}

	if err := db.NewSelect().
		Model(&ts).
		Relation("Child.Child").
		Scan(ctx); err != nil {
		panic(err)
	}
	fmt.Println(ts[0].ID, ts[0].ChildID)
	fmt.Println(ts[1].ID, ts[1].ChildID)
	fmt.Println(ts[2].ID, ts[2].ChildID)
}

type MainTable struct {
	ID      int64 `bun:",pk,notnull"`
	ChildID int64
	Child   *Parent `bun:",rel:has-one,join:child_id=id"`
}

type Parent struct {
	ID      int64  `bun:",pk,notnull"`
	ChildID int64  `bun:",nullzero"`
	Child   *Child `bun:",rel:has-one,join:child_id=id"`
}

type Child struct {
	ID   int64
	Name string
}

[kubakl]

Hi, first of all, thanks for picking up on this topic. I could finally reproduce it, here's the code:

package main

import (
	"context"
	"database/sql"
	"fmt"

	"github.com/uptrace/bun"
	"github.com/uptrace/bun/dialect/pgdialect"
	"github.com/uptrace/bun/driver/pgdriver"
	"github.com/uptrace/bun/extra/bundebug"
)

func main() {
	ctx := context.Background()

	sqldb := sql.OpenDB(pgdriver.NewConnector(pgdriver.WithDSN("postgres://user:pass@localhost:5433/test?sslmode=disable")))

	db := bun.NewDB(sqldb, pgdialect.New())
	db.AddQueryHook(bundebug.NewQueryHook(
		bundebug.WithVerbose(true),
		bundebug.FromEnv("BUNDEBUG"),
	))
	defer db.Close()

	if err := db.ResetModel(ctx, (*MainTable)(nil), (*Parent)(nil), (*Child)(nil)); err != nil {
		fmt.Println(err)
	}

	childs := []*Child{{Name: "Test 1"}, {Name: "Test 2"}}
	parents := []Parent{{Child1ID: 1}}
	mainTables := []MainTable{{ParentID: 1, Child2ID: 1}}

	db.NewInsert().Model(&childs).Exec(ctx)
	db.NewInsert().Model(&parents).Exec(ctx)
	db.NewInsert().Model(&mainTables).Exec(ctx)

	// query

	ts := []MainTable{}

	if err := db.NewSelect().
		Model(&ts).
		Relation("Child1").
		Relation("Child2").
		Relation("Parent.Child1").
		Relation("Parent.Child2").
		Scan(ctx); err != nil {
		panic(err)
	}

	defer func() {
		if recover() != nil {
			println("panicked")
		}
	}()
}

type MainTable struct {
	ID       int64   `bun:",pk,unique,autoincrement"`
	ParentID int64   `bun:",nullzero"`
	Parent   *Parent `bun:"par,rel:belongs-to,join:parent_id=id"`
	Child1ID int64   `bun:"child_1_id,nullzero"`
	Child1   *Child  `bun:"ch1,rel:has-one,join:child_1_id=id"`
	Child2ID int64   `bun:"child_2_id,nullzero"`
	Child2   *Child  `bun:"ch2,rel:has-one,join:child_2_id=id"`
}

type Parent struct {
	ID       int64  `bun:",pk,unique,autoincrement"`
	Child1ID int64  `bun:"child_1_id,nullzero"`
	Child1   *Child `bun:"ch1,rel:has-one,join:child_1_id=id"`
	Child2ID int64  `bun:"child_2_id,nullzero"`
	Child2   *Child `bun:"ch2,rel:has-one,join:child_2_id=id"`
}

type Child struct {
	ID   int64 `bun:",pk,unique,autoincrement"`
	Name string
}

[kubakl]

Additionally I noticed that if the model is referring to a database view instead of a table and you try to load a nullable relation it will fail with the same error: panic: reflect: call of reflect.Value.Field on ptr Value.

[Tiscs]

Additionally I noticed that if the model is referring to a database view instead of a table and you try to load a nullable relation it will fail with the same error: panic: reflect: call of reflect.Value.Field on ptr Value.

Could you provide the module versions referenced in go.mod? I just tried to reproduce this issue, but the unit test passed (based on v1.2.5 and v1.2.6).

[kubakl]

It's based on version v1.1.17

[kubakl]

After updating to 1.2.6 this particular example is indeed working. I will update once I can test it in my codebase.