mgo query select

gistfile1.go

package main

import (
	"log"

	"gopkg.in/mgo.v2"
	"gopkg.in/mgo.v2/bson"
)

func main() {
	session, err := mgo.Dial("127.0.0.1:27017")
	if err != nil {
		log.Fatalln(err)
	}

	datas := []bson.M{
		{
			"title":   "title1",
			"content": "content1",
			"extend":  "extend1",
		},
		{
			"title":   "title2",
			"content": "content2",
			"extend":  "extend2",
		},
		{
			"title":   "title3",
			"content": "content3",
			"extend":  "extend3",
		},
	}

	c := session.DB("test").C("test-select")
	if err := c.Insert(datas[0], datas[1], datas[2]); err != nil {
		log.Fatalln(err)
	}

	result1 := map[string]interface{}{}
	if err := c.Find(bson.M{"title": "title1"}).Select(nil).One(&result1); err != nil {
		log.Fatalln(err)
	}

	result2 := map[string]interface{}{}
	if err := c.Find(bson.M{"title": "title1"}).Select(bson.M{"content": 1}).One(&result2); err != nil {
		log.Fatalln(err)
	}

	result3 := map[string]interface{}{}
	if err := c.Find(bson.M{"title": "title1"}).Select(bson.M{"extend": 1}).One(&result3); err != nil {
		log.Fatalln(err)
	}

	results := []map[string]interface{}{}
	if err := c.Find(nil).Select(bson.M{"extend": 1}).All(&results); err != nil {
		log.Fatalln(err)
	}

	log.Println(result1, "\n", result2, "\n", result3, "\n", results)
	c.DropCollection()
}