Gorm Many2many error ON CONFLICT DO UPDATE postgresql

GORM Playground Link

https://github.com/go-gorm/playground/pull/426

Description

Many2many error on conflict

I use many2many models

type Application struct {
    ID        string `gorm:"primarykey"`
    Name      string
    Type      string
    Resources []Resource `json:"resources,omitempty" gorm:"many2many:application_resources;" faker:"-"`
}

type Resource struct {
    ID       string `gorm:"primarykey"`
    Name     string
    Type     string
    Packages []Package `json:"packages,omitempty" gorm:"many2many:resource_packages;" faker:"-"`
}

type Package struct {
    ID   string `gorm:"primarykey"`
    Name string
    Type string
}

In my case there is a single application with 2 resources that associate to the same package. The application update flow with FullSaveAssociations: true failed due to

ERROR: ON CONFLICT DO UPDATE command cannot affect row a second time (SQLSTATE 21000)
[2.167ms] [rows:0] INSERT INTO "packages" ("id","name","type") VALUES ('1','name','type'),('1','name','type') ON CONFLICT ("id") DO UPDATE SET "name"="excluded"."name","type"="excluded"."type"

Instead of inserting only a single package GORM tries to insert the same duplicate package - ('1','name','type') in a single INSERT command

I would expect that the save command would not failed and that only single package will be inserted.

Maybe there is a way to remove duplicates values before creating the INSERT statement for Associations

Comment From: okcthulhu

Also seeing this error on batch processing.