mongo-example/query.go

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	md "go.mongodb.org/mongo-driver/mongo"
	"myschools.me/suguo/mongo-example/mongo"
)

func query() {
	// 使用游标形式查询数据
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	client, _ := mongo.New()
	defer client.Disconnect(ctx)

	collection := client.Database("example").Collection("person")
	cur, err := collection.Find(ctx, bson.D{})
	if err != nil {
		log.Fatal(err)
	}
	defer cur.Close(ctx)
	for cur.Next(ctx) {
		var result bson.D
		var r2 Student
		err := cur.Decode(&result)
		if err != nil {
			log.Fatal(err)
		}
		err = cur.Decode(&r2)
		if err != nil {
			log.Fatal(err)
		}
		// do something with result....
		fmt.Println(result)
		fmt.Println(r2, r2.ID.Hex())
	}
	if err := cur.Err(); err != nil {
		log.Fatal(err)
	}
}

func queryBooking() {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	client, _ := mongo.New()
	defer client.Disconnect(ctx)

	collection := client.Database("example").Collection("booking")
	cur, err := collection.Find(ctx, bson.D{})
	if err != nil {
		log.Fatal(err)
	}
	defer cur.Close(ctx)

	for cur.Next(ctx) {
		var book Booking
		if err := cur.Decode(&book); err != nil {
			log.Fatal(err)
		}

		ret, _ := json.Marshal(book)
		fmt.Println(string(ret))
	}

	if err := cur.Err(); err != nil {
		log.Fatal(err)
	}
}

func queryResult() {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	client, _ := mongo.New()
	defer client.Disconnect(ctx)

	collection := client.Database("example").Collection("booking")
	book := &Booking{}
	if err := collection.FindOne(ctx, bson.M{"_id": "63d20bb744ecbc6b61a283ef"}).Decode(&book); err != nil {
		if err == md.ErrNoDocuments {
			//这里的md是mongo，我们封名名需要修改
			fmt.Println("record does not exist")
			return
		}
		log.Fatal(err)
	}
	fmt.Println(book)
}