This question already has answers here:
Golang mgo getting empty objects
(1 answer)
Golang mgo Finding
(2 answers)
Closed 4 years ago.
I write the code with Go to get value from specify key, but it's return only `_idà value
from my code
func main() {
mongoDialInfo := &mgo.DialInfo{
Addrs: []string{"localhost:27017"},
Database: "person",
Username: "user",
Password: "user",
Timeout: 60 * time.Second,
}
session, err := mgo.DialWithInfo(mongoDialInfo)
if err != nil {
panic(err)
}
defer session.Close()
c := session.DB("person").C("person")
result := Person{}
name := "Bill"
err = c.Find(bson.M{"name": name}).Select(bson.M{"surname": 1 }).One(&result)
if err != nil {
panic(err)
}
fmt.Println("Surname is ", result)
}
and the result from code is
{ObjectIdHex("5b9bb0b39b5c3e5733e1c8f7") }
Please help me to fix it.
Related
This question already has answers here:
Is mongodb client driver concurrent safe?
(1 answer)
goroutine create multiple mongodb connection
(1 answer)
Closed 21 days ago.
I've managed to connect to MongoDB and I've got this client object, can this be passed around and reused?
Or does it need to be created each time I want to interact with the database?
If it can be reused then ill move the database connection out to its own function and run it just once at startup.
package main
import (
"context"
"fmt"
"log"
"main/api"
"os"
"time"
"github.com/joho/godotenv"
"go.mongodb.org/mongo-driver/mongo"
"go.mongodb.org/mongo-driver/mongo/options"
)
type User struct {
Username string
Password string `bson:"password,omitempty"`
}
func main() {
if err := godotenv.Load(); err != nil {
log.Println("No .env file found")
}
uri := os.Getenv("MONGODB_URI")
serverAPIOptions := options.ServerAPI(options.ServerAPIVersion1)
clientOptions := options.Client().
ApplyURI(uri).
SetServerAPIOptions(serverAPIOptions)
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
client, err := mongo.Connect(ctx, clientOptions)
if err != nil {
log.Fatal(err)
}
usersColl := client.Database("sampleShop").Collection("users")
newUser := User{Username: "8282", Password: "Korean"}
result, err := usersColl.InsertOne(context.TODO(), newUser)
if err != nil {
panic(err)
}
fmt.Println(result)
fmt.Println(uri)
api.GetPaymentSession()
}
This question already has answers here:
How would I update multiple records based on different key in Mongo in one query?
(1 answer)
MongoDB update array of documents and replace by an array of replacement documents
(1 answer)
Closed last month.
I am trying to update a collection of multiple data in MongoDB using Golang at the same time, instead, it updates only one record, I'm using a for loop to perform this action
My filter code
if len(list_phone) > 1 {
for i := 0; i < len(list_phone); i++ {
update_userPhone, err := helpers.UpdatePhone(list_phone[i]["phone"].(string), list_phone[i]["email"].(string))
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
w.Write([]byte(`{"status:":"error", "error": true, "msg": "Something went wrong" }`))
return
}
json.NewEncoder(w).Encode(update_userPhone)
return
}
}
my update function
func UpdatePhone(phone string, email string) (bool, error) {
userCollection, _ := GetDBCollection("users")
ctx, cancel := context.WithTimeout(context.Background(), 100*time.Second)
id := email
filter := bson.M{"email": id}
update := bson.M{"$set": bson.M{"phone": phone}}
_, err := userCollection.UpdateOne(ctx, filter, update)
defer cancel()
if err != nil {
return false, err
}
return true, err
}
I have a problem finding an objectid through the query param called id.
I can see the id that arrives at the function until the moment of doing the query.
But when I try to use ObjectIDFromHex it returns 00000000000000000000000 and doesn't get the document from mongodb.
I'll leave a screenshot so you can see the full problem.
screenshot with IDE
The code is this.
func RetrieveUser(ID string) (models.User, error) {
ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
db := MongoCN.Database("mydatabase")
col := db.Collection("users")
var user models.User
objID, _ := primitive.ObjectIDFromHex(ID)
fmt.Println(ID)
fmt.Println(objID)
condition := bson.M{
"_id": objID,
}
err := col.FindOne(ctx, condition).Decode(&user)
user.Password = ""
if err != nil {
fmt.Println("User not found" + err.Error())
return user, err
}
return user, nil
}
I have a collections of 2,000,000 records
> db.events.count(); │
2000000
and I use golang mongodb client to connect to the database
package main
import (
"go.mongodb.org/mongo-driver/bson"
"go.mongodb.org/mongo-driver/mongo"
"go.mongodb.org/mongo-driver/mongo/options"
)
func main() {
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
client, err := mongo.Connect(ctx, options.Client().ApplyURI("mongodb://localhost:27888").SetAuth(options.Credential{
Username: "mongoadmin",
Password: "secret",
}))
if err != nil {
panic(err)
}
defer func() {
if err = client.Disconnect(ctx); err != nil {
panic(err)
}
}()
collection := client.Database("test").Collection("events")
var bs int32 = 10000
var b = true
cur, err := collection.Find(context.Background(), bson.D{}, &options.FindOptions{
BatchSize: &bs, NoCursorTimeout: &b})
if err != nil {
log.Fatal(err)
}
defer cur.Close(ctx)
s, n := runningtime("retrive db from mongo and publish to kafka")
count := 0
for cur.Next(ctx) {
var result bson.M
err := cur.Decode(&result)
if err != nil {
log.Fatal(err)
}
bytes, err := json.Marshal(result)
if err != nil {
log.Fatal(err)
}
count++
msg := &sarama.ProducerMessage{
Topic: "hello",
// Key: sarama.StringEncoder("aKey"),
Value: sarama.ByteEncoder(bytes),
}
asyncProducer.Input() <- msg
}
But the the program only retrives only about 600,000 records instead of 2,000,000 every times I ran the program.
$ go run main.go
done
count = 605426
nErrors = 0
2020/09/18 11:23:43 End: retrive db from mongo and publish to kafka took 10.080603336s
I don't know why? I want to retrives all 2,000,000 records. Thanks for any help.
Your loop fetching the results may end early because you are using the same ctx context for iterating over the results which has a 10 seconds timeout.
Which means if retrieving and processing the 2 million records (including connecting) takes more than 10 seconds, the context will be cancelled and thus the cursor will also report an error.
Note that setting FindOptions.NoCursorTimeout to true is only to prevent cursor timeout for inactivity, it does not override the used context's timeout.
Use another context for executing the query and iterating over the results, one that does not have a timeout, e.g. context.Background().
Also note that for constructing the options for find, use the helper methods, so it may look as simple and as elegant as this:
options.Find().SetBatchSize(10000).SetNoCursorTimeout(true)
So the working code:
ctx2 := context.Background()
cur, err := collection.Find(ctx2, bson.D{},
options.Find().SetBatchSize(10000).SetNoCursorTimeout(true))
// ...
for cur.Next(ctx2) {
// ...
}
// Also check error after the loop:
if err := cur.Err(); err != nil {
log.Printf("Iterating over results failed: %v", err)
}
I checked out the answer here but this uses the old and unmaintained mgo. How can I find all documents in a collection using the mongo-go-driver?
I tried passing a nil filter, but this does not return any documents and instead returns nil. I also checked the documentation but did not see any mention of returning all documents. Here is what I've tried with aforementioned result.
client, err := mongo.Connect(context.TODO(), "mongodb://localhost:27017")
coll := client.Database("test").Collection("albums")
if err != nil { fmt.Println(err) }
// we can assume we're connected...right?
fmt.Println("connected to mongodb")
var results []*Album
findOptions := options.Find()
cursor, err := coll.Find(context.TODO(), nil, findOptions)
if err != nil {
fmt.Println(err) // prints 'document is nil'
}
Also, I'm about confused about why I need to specify findOptions when I've called the Find() function on the collection (or do I not need to specify?).
Here is what I came up with using the official MongoDB driver for golang. I am using godotenv (https://github.com/joho/godotenv) to pass the database parameters.
//Find multiple documents
func FindRecords() {
err := godotenv.Load()
if err != nil {
fmt.Println(err)
}
//Get database settings from env file
//dbUser := os.Getenv("db_username")
//dbPass := os.Getenv("db_pass")
dbName := os.Getenv("db_name")
docCollection := "retailMembers"
dbHost := os.Getenv("db_host")
dbPort := os.Getenv("db_port")
dbEngine := os.Getenv("db_type")
//set client options
clientOptions := options.Client().ApplyURI("mongodb://" + dbHost + ":" + dbPort)
//connect to MongoDB
client, err := mongo.Connect(context.TODO(), clientOptions)
if err != nil {
log.Fatal(err)
}
//check the connection
err = client.Ping(context.TODO(), nil)
if err != nil {
log.Fatal(err)
}
fmt.Println("Connected to " + dbEngine)
db := client.Database(dbName).Collection(docCollection)
//find records
//pass these options to the Find method
findOptions := options.Find()
//Set the limit of the number of record to find
findOptions.SetLimit(5)
//Define an array in which you can store the decoded documents
var results []Member
//Passing the bson.D{{}} as the filter matches documents in the collection
cur, err := db.Find(context.TODO(), bson.D{{}}, findOptions)
if err !=nil {
log.Fatal(err)
}
//Finding multiple documents returns a cursor
//Iterate through the cursor allows us to decode documents one at a time
for cur.Next(context.TODO()) {
//Create a value into which the single document can be decoded
var elem Member
err := cur.Decode(&elem)
if err != nil {
log.Fatal(err)
}
results =append(results, elem)
}
if err := cur.Err(); err != nil {
log.Fatal(err)
}
//Close the cursor once finished
cur.Close(context.TODO())
fmt.Printf("Found multiple documents: %+v\n", results)
}
Try passing an empty bson.D instead of nil:
cursor, err := coll.Find(context.TODO(), bson.D{})
Also, FindOptions is optional.
Disclaimer: I've never used the official driver, but there are a few examples at https://godoc.org/go.mongodb.org/mongo-driver/mongo
Seems like their tutorial is outdated :/