Gorm Unnecessary SELECT query when preloading a has-many association

GORM Playground Link

• https://github.com/go-gorm/playground/pull/626

Description

Consider these models:

type Skill struct {
    gorm.Model
    ManagerID uint
    Name      string
}

type Manager struct {
    gorm.Model
    Name   string
    Skills []Skill
}

type Project struct {
    gorm.Model
    Name      string
    ManagerID uint
    Manager   Manager
}

A Project has one Manager who can have many Skill.

One could use the following code to retrieve a Project along with its associated Manager and Skills:

var result Project
DB.Joins("Manager").Preload("Manager.Skills").First(&result, myProjectID)

I was excepting such code to generate at most two queries: - SELECT * FROM projects with a LEFT JOIN managers clause - SELECT * FROM skills

But it turns out that it generates an additional, unnecessary query: - SELECT * FROM managers

The has-many association Skills should have been loaded by using the primary keys returned in the first query with the LEFT JOIN managers clause. There's no point in having an additional separate query in this case.

Thanks for your help!