Gorm How do I get the column name from the model struct field

Your Question

How do I get the column name from the model struct field？

Model:

type Animal struct {
  AnimalID int64     `gorm:"column:beast_id"`        
  Birthday time.Time `gorm:"column:day_of_the_beast"`
  Age      int64     `gorm:"column:age_of_the_beast"` 
}

I want to get the value of the column tag

The document you expected this should be explained

Expected answer

GORM has a method that returns the column name

Comment From: s-takehana

How about this?

package main

import (
    "fmt"
    "gorm.io/driver/postgres"
    "gorm.io/gorm"
    "time"
)

type Animal struct {
    AnimalID int64     `gorm:"column:beast_id"`
    Birthday time.Time `gorm:"column:day_of_the_beast"`
    Age      int64     `gorm:"column:age_of_the_beast"`
}

func main() {
    dsn := "host=postgres user=postgres password=***** dbname=postgres port=5432"
    db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
    if err != nil {
        panic("failed to connect database")
    }

    db.AutoMigrate(&Animal{})

    result, _ := db.Debug().Migrator().ColumnTypes(&Animal{})
    for _, v := range result {
        fmt.Println(v.Name())
    }
}

2021/07/04 12:34:50 /go/pkg/mod/gorm.io/driver/postgres@v1.1.1-0.20210614014255-4c6dc88331ab/migrator.go:68
[0.472ms] [rows:-] SELECT CURRENT_DATABASE()

2021/07/04 12:34:50 /go/pkg/mod/gorm.io/driver/postgres@v1.1.1-0.20210614014255-4c6dc88331ab/migrator.go:302
[9.747ms] [rows:-] SELECT column_name, is_nullable, udt_name, character_maximum_length, numeric_precision, numeric_precision_radix, numeric_scale, datetime_precision FROM information_schema.columns WHERE table_catalog = 'postgres' AND table_schema = CURRENT_SCHEMA() AND table_name = 'animals'
beast_id
day_of_the_beast
age_of_the_beast

Comment From: li-zeyuan

thank you for your help

Comment From: github-actions[bot]

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Comment From: nermolov

Is there any way to map these to the struct field names? Some of my models have fields that are skipped for GORM so directly mapping this array to a field name array from reflect doesn't work.

Comment From: pavelpatrin

@nermolov agree, SELECT * is almost always bad idea, since we already knows which fields struct has. Database schema may have additional column with large amount of data that is not used by a Gorm Model.