Gorm Association on SQLite gives unsupported data type: <nil>

Your Question

Hi, I am getting an unsupported data type: <nil> while trying to retrieve associated data. I can see it in the database and it's probably me doing something incorrectly.

Can anyone help?

This is my command, if I remove the Association then everything seems to work so the "FirstOrCreate" is working.

    block := model.Block{
        Filename: "test.blk",
    }

    err := s.dbConnection.DB.FirstOrCreate(&block).Association("BlockVersion").Find(&block.BlockVersion)
    if err != nil {
        log.Fatalln("There was error :- ", err)
    }

Here are my models.

type BlockVersion struct {
    gorm.Model
    BlockID  uint
    Filesize int64
}

type Block struct {
    gorm.Model
    Filename     string
    BlockVersion []BlockVersion
}

Once I have it working, the BlockVersion may contain more than 1 record, so I was hoping to return "only" the latest one.

I have placed some images below to show what is currently in the database.

Expected answer

I would like for the last (latest) record of "BlockVersion" to be populated inside the "Block".

Block

BlockVersion

Comment From: iangregsondev

Oh,

I got it working.

Seems I might have been doing it wrong.

I am now using

    err = s.dbConnection.DB.Model(&block).Association("BlockVersion").Find(&block.BlockVersion)

This now works.

So doing this does not.

      s.dbConnection.DB.FirstOrCreate(&block) // Get main table first

      err := s.dbConnection.DB.FirstOrCreate(&block).Association("BlockVersion").Find(&block.BlockVersion)

I thought you could chain then?

Comment From: a631807682

After a Chain method, Finisher Method, GORM returns an initialized gorm.DB instance, which is NOT safe to reuse anymore, you should use a New Session Method to mark the gorm.DB as shareable.

https://gorm.io/docs/method_chaining.html#New-Session-Method