无法使用Gorm Postgresql设置外键

Question

I'm building a Golang backend using jinzhu/gorm and I'm having some troubles trying to set up a relation between two tables e.g. Items and Manufacturers using a foreign key.

I'm following the steps at jinzhu.me/gorm/models but I'm honestly finding myself puzzled coming from a more straightforward approach of manually writing tables etc, for instance, using go pq.

item.go:

package model

import "github.com/jinzhu/gorm"

type Item struct {
    gorm.Model
    Item         string       `gorm:"primary_key"`
    Manufacturer Manufacturer `gorm:"ForeignKey:Name"`
}

manufacturer.go:

package model

import "github.com/jinzhu/gorm"

type Manufacturer struct {
    gorm.Model
    Name string `gorm:"primary_key"`
}

I get no errors nor warnings. Inspecting my tables I noticed no correlation was created. Item does not have Manufacturer field.

What I tried so far:

• Not explicitly writing gorm:"ForeignKey:Name" since Manufacturer field is already a Manufacturer
• Writing gorm:"ForeignKey:Name;AssociationForeignKey:Name"
• Manually associating them with db.Model(&model.Item{}).Related(&model.Manufacturer{})
• Manually associating them with db.Model(&model.Item{}).Related(&model.Manufacturer{}, "Manufacturer")
• Manually associating them with db.Model("items").Related("manufacturers"). They get created with this name on Postgresql even though their model's name is singular.

EDIT:

Trying something like

type Item struct {
    Item             string       `gorm:"primary_key"`
    Manufacturer     Manufacturer
    ManufacturerID   int
}

type Manufacturer struct {
    ID uint
    Name string
}

Leads to the same result. No foreign key is created and I'm able to insert new items with a non-existent Manufacturer.

What Am I doing wrong? Am I missing something?

Answer 1

You have to do something like:

type Item struct {
    gorm.Model
    Item         string       `gorm:"primary_key"`
    ManufacturerName string   `sql:"type:varchar REFERENCES manufacturers(name)"`
    Manufacturer Manufacturer `gorm:"ForeignKey:ManufacturerName;AssociationForeignKey:Name`
}

To tell it to a) Use ManufacturerName as the foreign key, and B) use Name on the other table.

Or you can just do:

type Item struct {
    gorm.Model
    Item         string       `gorm:"primary_key"`
    ManufacturerID uint       `sql:"type:uint REFERENCES manufacturers(id)"`
    Manufacturer Manufacturer `gorm:"ForeignKey:Man;AssociationForeignKey:Name"`
}