How to update with a has many relationship

Question

I use the gorm with the has many。 This is my model

type Pro struct {
    Model
    TaxRate              []TaxRate  `json:"taxRate" gorm:"constraint:OnUpdate:CASCADE;"`
}

type TaxRate struct {
    ID        uint
    Tax       float64
    ProjectID uint
}

but when I update the project, I found that the TaxRate just insert the record not update. This is my update operation

result:=pRepo.db.Session(&gorm.Session{FullSaveAssociations: true}).Updates(p)

user_8981262 · Answer

type Pro struct {
    Model
    TaxRate []TaxRate `json:"taxRate" gorm:"foreignKey:ProjectID;constraint:OnUpdate:CASCADE;"`
}