Golang Gorm not retrieving data from associated table-CodePudding

I'm working on a Gin app using Gorm with MySQL. In order to define a belongs to relationship in a Gorm Model, you have to do the following (example taken from Gorm docs):

// `User` belongs to `Company`, `CompanyID` is the foreign key
type User struct {
  gorm.Model
  Name      string
  CompanyID int
  Company   Company
}

type Company struct {
  ID   int
  Name string
}

That's what I did with my models:

type Record struct {
    Barcode string `json:"barcode" gorm:"size:48;unique;not null" sql:"index"`
    Name    string `json:"name" gorm:"size:160;unique;not null"`
    ArtistID   uint     `json:"artist_id"`
    Artist     Artist   `gorm:"foreignKey:ArtistID;references:ID"`
    CategoryID uint     `json:"category_id"`
    Category   Category `gorm:"foreignKey:CategoryID;references:ID"`

    NumOfRecords        int         `json:"num_of_records" gorm:"not null"`
    OriginalReleaseDate *utils.Date `json:"original_release_date" gorm:"default:null;type:date"`
    ReissueReleaseDate  *utils.Date `json:"reissue_release_date" gorm:"default:null;type:date"`
    SideColor           *string     `json:"side_color" gorm:"default:null"`
    BarcodeInRecord     *bool       `json:"barcode_in_record" gorm:"default=true"`
    gorm.Model
}

type Category struct {
    Name        string `json:"name" gorm:"size:60;unique;not null"`
    Description string `json:"description" gorm:"size:120"`
    Parent      uint   `json:"parent" gorm:"default:null"`
    Active      bool   `json:"active" gorm:"default:true"`
    gorm.Model
}

type Artist struct {
    Name            string `json:"name" gorm:"size:120;unique;not null"`
    Type            string `json:"type" gorm:"default:null"`
    CountryOfOrigin string `json:"countryOfOrigin" gorm:"default:null"`
    gorm.Model
}

yet when getting data back, those two associations are not being populated:

{
    "data": {
        "barcode": "1231231231231292",
        "name": "ABCD 12342",
        "artist_id": 2,
        "Artist": {
            "name": "",
            "type": "",
            "countryOfOrigin": "",
            "ID": 0,
            "CreatedAt": "0001-01-01T00:00:00Z",
            "UpdatedAt": "0001-01-01T00:00:00Z",
            "DeletedAt": null
        },
        "category_id": 9,
        "Category": {
            "name": "",
            "description": "",
            "parent": 0,
            "active": false,
            "ID": 0,
            "CreatedAt": "0001-01-01T00:00:00Z",
            "UpdatedAt": "0001-01-01T00:00:00Z",
            "DeletedAt": null
        },
        "num_of_records": 2,
        "original_release_date": "1965-02-24",
        "reissue_release_date": null,
        "side_color": null,
        "barcode_in_record": null,
        "ID": 1,
        "CreatedAt": "2022-04-25T12:53:32.275578-04:00",
        "UpdatedAt": "2022-04-25T12:53:32.275578-04:00",
        "DeletedAt": null
    }
}

any idea what's going on there?

CodePudding user response：

What does the code look like that is saving the data to the db?

I'm guessing that you probably need to use FullSaveAssociations something like this:


DB().Session(&gorm.Session{FullSaveAssociations: true}).Save(&d)

To get the data back, you need to use Preloads.


DB().Preload("Artist").Preload("Category").First(&d)

you can also use

.Preload(clause.Associations)

to load them all. You can use this with other Preloads to go deeper.

https://gorm.io/docs/preload.html#content-inner