Golang slices of struct or newbie trouble building REST

and need your help.
Wanted to build simple api and stuck with some problem.
I've choose gin and database/sql with postgres driver

package main

import (
	"database/sql"
	"fmt"

	"github.com/gin-gonic/gin"

	_ "github.com/lib/pq"
)

func main() {

	router := gin.Default()
	router.GET("/search/:text", SearchWord)
	router.Run(":8080")

}

I need to make query to DB and make json out of this request.

func checkErr(err error) {
	if err != nil {
		panic(err)
	}
}

type Message struct {
	ticket_id int    `json:"ticket_id"`
	event     string `json:"event"`
}

func SearchWord(c *gin.Context) {
    word := c.Params.ByName("text")
	db, err := sql.Open("postgres", "host=8.8.8.8 user= password= dbname=sample")
	defer db.Close()
	checkErr(err)
	rows, err2 := db.Query("SELECT ticket_id,event FROM ....$1, word)
	checkErr(err)
	for rows.Next() {
		var ticket_id int
		var event string
		err = rows.Scan(&ticket_id, &event)
		checkErr(err)
		fmt.Printf("%d | %s \n\n", ticket_id, event)
	}

}

This coda working nice, but when i need to make json.
I need to make struct of a row

type Message struct {
	ticket_id int    `json:"ticket_id"`
	event     string `json:"event"`
}

an then i need to create slice , and append every rows.Next() loop an than answer to browser with Json...

c.JSON(200, messages)

But how to do that...don't know

disclaimer: I am brand new to go

Since you Scanned your column data into your variables, you should be able to initialize a structure with their values:

m := &Message{ticket_id: ticket_id, event: event}

You could initialize a slice with

s := make([]*Message, 0)

And then append each of your message structs after instantiation:

s = append(s, m)

Because I'm not too familiar with go there are a couple things i'm not sure about:

• after copying data from query to your vars using rows.Scan does initializing the Message struct copy the current iterations values as expected??

• If there is a way to get the total number of rows from your query it might be slighlty more performant to initialize a static length array, instead of a slice?

• I think @inf deleted answer about marshalling your Message to json down the line might need to be addressed, and Message field's might need to be capitalized

copied from @inf:

> The names of the members of your struct need be capitalized so that
> they get exported and can be accessed.
>
> type Message struct {
> Ticket_id int json:"ticket_id"
> Event string json:"event" }

I'm going to cheat a little here and fix a few things along the way:

First: open your database connection pool once at program start-up (and not on every request).

Second: we'll use sqlx to make it easier to marshal our database rows into our struct.

<!-- language: lang-go -->

package main

var db *sqlx.DB

func main() {
    var err error
    // sqlx.Connect also checks that the connection works.
    // sql.Open only "establishes" a pool, but doesn't ping the DB.
    db, err = sqlx.Connect("postgres", "postgres:///...")
    if err != nil {
        log.Fatal(err)
    }

    router := gin.Default()
    router.GET("/search/:text", SearchWord)
    router.Run(":8080")

}

// in_another_file.go

type Message struct {
    TicketID int    `json:"ticket_id" db:"ticket_id"`
    Event     string `json:"event" db:"event"`
}

func SearchWord(c *gin.Context) {
    word := c.Params.ByName("text")
    // We create a slice of structs to marshal our rows into
    var messages []*Message{}
    // Our DB connection pool is safe to use concurrently from here
    err := db.Select(&messages, "SELECT ticket_id,event FROM ....$1, word)
    if err != nil {
        http.Error(c.Writer, err.Error(), 500)
        return
    }
    
    // Write it out using gin-gonic's JSON writer.
    c.JSON(200, messages)
}

I hope that's clear. sqlx also takes care of calling rows.Close() for you, which will otherwise leave connections hanging.