Query Beego problem

Question

I’m having problems to mount a Query in Go, using the Beego framework.

Error:

2018/12/20 09:21:32.104 [C] [asm_amd64.s:522] Handler Crashed with error Runtime error: invalid memory address or nil Pointer dereference 2018/12/20 09:21:32.104 [C] [asm_amd64.s:522] C:/Go/src/Runtime/asm_amd64.s:522 2018/12/20 09:21:32.104 [C] [asm_amd64.s:522] C:/Go/src/Runtime/Panic.go:513 2018/12/20 09:21:32.104 [C] [asm_amd64.s:522] C:/Go/src/Runtime/Panic.go:82 2018/12/20 09:21:32.104 [C] [asm_amd64.s:522] C:/Go/src/Runtime/signal_windows.go:204 2018/12/20 09:21:32.105 [C] [asm_amd64.s:522] C:/Users/Joao/go/src/hello/controllers/cities.go:35 2018/12/20 09:21:32.109 [C] [asm_amd64.s:522] C:/Users/Joao/go/src/github.com/astaxie/beego/router.go:834 2018/12/20 09:21:32.110 [C] [asm_amd64.s:522] C:/Go/src/net/http/server.go:2741 2018/12/20 09:21:32.110 [C] [asm_amd64.s:522] C:/Go/src/net/http/server.go:1847 2018/12/20 09:21:32.111 [C] [asm_amd64.s:522] C:/Go/src/Runtime/asm_amd64.s:1333 2018/12/20 09:21:32.111 [server.go:2977] [HTTP] http: Multiple Response.Writeheader calls

Controller:

package controllers

import (
    "hello/models"

    "github.com/astaxie/beego"
    "github.com/astaxie/beego/orm"
    _ "github.com/lib/pq"
)

type CidadesController struct {
    beego.Controller
}

func init() {
    beego.BConfig.WebConfig.AutoRender = false
    orm.RegisterDriver("postgres", orm.DRPostgres)
    orm.RegisterDataBase("default", "User", "postgres:senha@/nomeDoDB? 
    charset=utf8", 30)
}

func (this *CidadesController) Get() {

    var cidade []models.Cidade

    cidades, err := orm.NewQueryBuilder("postgres")

    if err != nil {
        //
    }

    cidades.Select("cid_codigo",
        "cid_nome").
        From("ger_cidade").
        Limit(10).
        Offset(0)

    sql := cidades.String()

    o := orm.NewOrm()
    o.Raw(sql, 20).QueryRows(&cidade)
}

Model:

package models

import (
    "github.com/astaxie/beego/orm"
)

type Cidade struct {
    Id   int    `db:"cid_codigo"`
    Name string `db:"cid_nome"`
}

func init() {
    orm.RegisterModel(new(Cidade))
}

From what I understand is coming back a err in Query, but as I am not treating is giving this error. What I do not understand is why return error in query? From what I understand it’s all right.

RESOLVED

You can’t use Querybuilder with Postgres, it has to be on Raw

Answer 1

In the Beego framework it is not possible to use the QueryBuilder with PgSql, with only MySql. So it was like this:

No Controller:

package controllers

import (
    "fmt"
    "hello/models"

    "github.com/astaxie/beego"
    "github.com/astaxie/beego/orm"
    _ "github.com/lib/pq"
)

type CidadesController struct {
    beego.Controller
}

func init() {
    beego.BConfig.WebConfig.AutoRender = false
    orm.RegisterDriver("postgres", orm.DRPostgres)
    orm.RegisterDataBase("default", "postgres", "dbname=nomeDoDB host=localhost 
user=user password=senhaDoDb port=5432 sslmode=disable", 30)
}

func (this *CidadesController) Get() {

    o := orm.NewOrm()
    o.Using("default")

    var cidade []models.Cidade

    res, err := o.Raw("SELECT cid_codigo as id, cid_nome, est_codigo FROM 
    geral.ger_cidade").QueryRows(&cidade)

    if err != nil {
        fmt.Println(err)
        return
    }

    if res == 0 {
        fmt.Println("Sem registros")
        return
    }

    this.Data["json"] = &cidade
    this.ServeJSON()
}

No Model:

package models

import (
    "github.com/astaxie/beego/orm"
)

type Cidade struct {
    Id         int    `json:"id" db:"nomeDoCampoNoDB"`
    Cid_nome   string `json:"name" db:"nomeDoCampoNoDB"`
    Est_codigo int    `json:"codigo_estado" db:"nomeDoCampoNoDB"`
}

func init() {
    orm.RegisterModel(new(Cidade))
}

I used sql "pure" to do the Query. In my view, it is not clear in the documentation that I can not use the QueryBuilder with PgSql. If anyone wants to take a look at the documentation where it talks about QueryBuilder here is the link: https://beego.me/docs/mvc/model/querybuilder.md