inital commit

find.go

@@ -0,0 +1,110 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/mongo"
+	"go.mongodb.org/mongo-driver/mongo/options"
+)
+
+func checkFindErr(err error) {
+	if err != nil {
+		if err == mongo.ErrNoDocuments {
+			return
+		}
+		log.Fatal(err)
+	}
+}
+
+func findAll(ctx context.Context, col *mongo.Collection) {
+	ctx, span := FollowSpan(ctx, "findAll")
+	defer span.End()
+
+	fmt.Println("replaceOne document...")
+	cursor, err := col.Find(ctx, bson.M{})
+	checkFindErr(err)
+
+	var books []Book
+	err = cursor.All(ctx, &books)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("Finded %d docs:\n%v\n", len(books), books)
+	fmt.Println("=============================")
+}
+
+func find(ctx context.Context, col *mongo.Collection) {
+	ctx, span := FollowSpan(ctx, "find")
+	defer span.End()
+
+	opts := options.Find().SetSort(bson.M{"rating": 1})
+
+	cursor, err := col.Find(ctx, bson.M{"year": 2022}, opts)
+	checkFindErr(err)
+
+	var books []Book
+	err = cursor.All(ctx, &books)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Println("Search documents where year equal 2022...")
+	fmt.Printf("Finded %d docs:\n%v\n", len(books), books)
+	fmt.Println("=============================")
+}
+
+func findWithCondition(ctx context.Context, col *mongo.Collection) {
+	ctx, span := FollowSpan(ctx, "findWithCondition")
+	defer span.End()
+
+	filter := bson.M{"year": bson.M{"$gt": 2020}}
+
+	cursor, err := col.Find(ctx, filter)
+	checkFindErr(err)
+
+	var books []Book
+	err = cursor.All(ctx, &books)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Println("Search documents where year greather then 2020...")
+	fmt.Printf("Finded %d docs:\n%v\n", len(books), books)
+	fmt.Println("=============================")
+}
+
+func findWithOrCondition(ctx context.Context, col *mongo.Collection) {
+	ctx, span := FollowSpan(ctx, "findWithOrCondition")
+	defer span.End()
+
+	filter := bson.M{
+		"$or": bson.A{
+			bson.M{
+				"year": bson.M{"$gte": 2020},
+			},
+			bson.M{
+				"author": "Касун Индрасири",
+			},
+		},
+	}
+
+	findOptions := options.Find()
+	findOptions.SetProjection(bson.M{"author": 0})
+
+	cursor, err := col.Find(ctx, filter, findOptions)
+	checkFindErr(err)
+
+	var books []Book
+	err = cursor.All(ctx, &books)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Println("Search documents where year greather then 2020 AND author is 'Касун Индрасири'...")
+	fmt.Printf("Finded %d docs:\n%v\n", len(books), books)
+	fmt.Println("=============================")
+}