[Question] Query data with filters on associated tables. about gorm.io

[a631807682]

Preload is a combined method, you need to specify their relationship conditions separately, in this case you can use Joins.

[a631807682]

This is supported, if you still have problem, you can submit an issue and a reproduction link in gorm.
https://gorm.io/docs/preload.html#Preload-with-conditions

[droslean]

@a631807682 Thanks for the response. You can see the description of the issue to reproduce it. I am doing exactly what the documentation says, but still gormdb load all the contents. I have see in the debug logs that it does the correct query, but still are Contents that shouldn't be based on the condition I added in Metadata.

[a631807682]

I don't understand what you want to query from your description. Your Preload restricts the query of Metadata, but it seems that what you want to filter is Content, but you also said that SQL query is correct.
I think the scenario you describe is similar to this test case, can you tell me where is the difference
https://github.com/go-gorm/gorm/blob/master/tests/preload_test.go#L188

[droslean]

@a631807682 My goal is to get all Content with empty Metadata.component. How can I achieve this? Based on the documents, it should just work with using the Preload, but it doesn't, and I am trying to figure out why.

[a631807682]

It cannot be reproduced, maybe you should update the gorm version, if there is still a problem, please provide a reproduction link.

func TestGORM(t *testing.T) {
	DB.Migrator().DropTable(&Content{}, &Metadata{})
	DB.AutoMigrate(&Content{}, &Metadata{})

	contents := []Content{
		{Data: "data 1", Metadata: Metadata{Component: "not empty", Locale: "en"}},
		{Data: "data 2", Metadata: Metadata{Component: "", Locale: "zh"}},
		{Data: "data 3", Metadata: Metadata{Component: "not empty", Locale: "en"}},
	}

	DB.Create(&contents)

	var contents2 []Content
	DB.Preload("Metadata", "component <> ''").Find(&contents2)
	for i := 0; i < len(contents); i++ {
		expect := contents[i]
		got := contents2[i]

		tests.AssertObjEqual(t, expect, got, "Data", "Domain")

		if got.Data == "data 2" { // filter
			tests.AssertEqual(t, got.Metadata.ID, 0)
			tests.AssertEqual(t, got.Metadata.Component, "")
			tests.AssertEqual(t, got.Metadata.Locale, "")
			continue
		}
		tests.AssertObjEqual(t, expect.Metadata, got.Metadata, "Component", "Locale")
	}
}

[droslean]

@a631807682 The problem arises when I am trying to filter the domain on Contents. Instead, gormdb returns all the content for the specific domain with empty Metadata.

It seems that

r.db.WithContext(ctx).Preload("Metadata", "component <> ''").Where("domain = ?", domain).Find(&contents)

The Preload and the Where are not connected.

[droslean]

@a631807682 So it seems that I should do something like:
r.db.WithContext(ctx).Joins("Metadata").Where("domain = ? AND component <> ''", domain).Find(&contents)