如何在功能中修改GORM DB指针？

Question

I have a REST API application written in Go, which uses GORM as ORM. During refactoring of some parts, I wanted to move some common operations to an external function ApplyToDBQuery(query *gorm.DB), which takes a pointer to the DB query and modifies it, so that the modified query can be used later.

Example usage:

query = shared.DB.Debug()
req.ApplytoDBQuery(query)
if query.find(&data).Error != nil {...}

func (this *MyCustomRequest) ApplyToDBQuery(query *gorm.DB) {
    query.Limit(...)
    query.Offset(...)
    query.Where(...)
}

I thought, that since I'm passing a pointer to the function, the original query should've been modified, but nothing really happened to the original query.

I've also tried passing a pointer to pointer ApplyToDBQuery(query **gorm.DB), returning the modified pointer ApplyToDBQuery(query *gorm.DB) *gorm.DB and out of lack of ideas, even a combination of these two - ApplyToDBQuery(query **gorm.DB) *gorm.DB

Answer 1

Gorm object clone itself for every operation, therefore the original pointed value is never changed.

You should return the latest version of gorm.DB:

return query.Limit(...).Offset(...).Where(...)