This is part of my collection schema in mongodb:
{ "_id" : ObjectId("55e1eef5255da6d384754642"), "name" : [ "Web, Mobile & Software Dev", "Movil y desarrollo de software" ] } { "_id" : ObjectId("55e1f2d0255da6d38475464b"), "name" : [ "IT & Networking", "TI y Redes" ] } ...
Right now i can get the info like this:
err := r.Coll.Find(bson.M{}).Select(bson.M{"name": bson.M{"$slice": []int{1, 1}}}).All(&result.Data)
but i want "name" to return a string instead of a single value array, so i dont have to index it inside my frontend if no need.
very limited comments i need 2000 poits for editing my post and add more things it seems, this is not answer but maybe, so i have to loop it?, isnt better way?
err := r.Coll.Find(bson.M{}).Select(bson.M{"name": bson.M{"$slice": []int{1, 1}}}).All(&result.Data)
if err != nil {
return result, err
}
type skillnew struct {
Id bson.ObjectId `json:"id,omitempty" bson:"_id,omitempty"`
Name string `bson:"name,omitempty" json:"name,omitempty"`
}
skillsallnew := make([]skillnew, len(result.Data))
for i := range result.Data {
skillsallnew[i] = skillnew{result.Data[i].Id, result.Data[i].Name[0]}
}
Related
I have a JSON file that follows a format like this for each record containing the names of various cities across the world.
{
"_id": {
"$oid": "5f856f2ee2d00c1818791982"
},
"name": "Sant Julia de Loria",
"all_names": "Sant Julià de Lòria, Sant Julia de Loria, San Julia,San Julià,Sant Julia de Loria,Sant Julià de Lòria,Sant-Zhulija-de-Lorija,sheng hu li ya-de luo li ya,Сант-Жулия-де-Лория,サン・ジュリア・デ・ロリア教区,圣胡利娅-德洛里亚,圣胡利娅－德洛里亚",
"alternate_names": "San Julia,San Julià,Sant Julia de Loria,Sant Julià de Lòria,Sant-Zhulija-de-Lorija,sheng hu li ya-de luo li ya,Сант-Жулия-де-Лория,サン・ジュリア・デ・ロリア教区,圣胡利娅-德洛里亚,圣胡利娅－德洛里亚",
"country_code": "AD",
"country_name": "Andorra"
}
My app basically returns the name of the city when querying it through a URL parameter. This is supposed to pass through a regex filter and then searches the JSON for the appropriate city name.
func searchCity(w http.ResponseWriter, r *http.Request) { // GET request that takes in a url param and returns a list of cities from the DB
w.Header().Set("Content-Type", "application/json")
values := r.URL.Query()
city := values["city_name"] // Assigns url param from route `/suggest?city_name=` to 'city'
cityCollection := client.Database(os.Getenv("CITY_DB")).Collection(os.Getenv("COL_CITY")) // Holds 'city' collection from DB
if len(city) == 0 {
w.WriteHeader(http.StatusOK)
w.Write([]byte(`{"Error": "City name cannot be empty!"}`))
return
}
filter := bson.D{ //Regex filter for querying the input through the DB
primitive.E{
Key: "all_names", Value: primitive.Regex{
Pattern: city[0], Options: "i",
},
},
}
cursor, err := cityCollection.Find(r.Context(), filter) // Query to find city is declared with cursor
if err != nil {
log.Fatal(err)
w.WriteHeader(http.StatusInternalServerError)
w.Write([]byte(`{"Error": "Could not execute cursor into query."}`))
return
}
var cityList []City
for cursor.Next(context.TODO()) { // Runs through each document entry in DB to see if regex matches
var cities City
err := cursor.Decode(&cities)
if err != nil {
log.Fatal(err)
w.WriteHeader(http.StatusInternalServerError)
w.Write([]byte(`{"Error": "Could not run cursor."}`))
return
}
cityList = append(cityList, cities) // List of cities is appended to cityList
}
w.WriteHeader(http.StatusOK)
if len(cityList) == 0 {
w.Write([]byte(`{"cities": []}`))
return
}
json.NewEncoder(w).Encode(cityList)
}
The City type model that's used to create the cityList object holds the correct values.
type City struct {
Name string `bson:"name" json:"name"`
Country string `bson:"country" json:"country"`
}
I've been trying to return the country_name along with the city name but I can't figure how to write it into the filter properly.
I have an endpoint where users can filter a mongo collection using query parameters. If I have just one query parameter e.g. title, I can do this -
filter := bson.M{}
if params.Title != "" {
filter = bson.M{"title": params.Title}
}
However, if I have more than one query parameter, I can't seem to get how to append to the bson object.
I tried this -
filter := []bson.M{}
if params.Title != "" {
filter = append(filter, bson.M{"title": params.Title})
}
if params.Description != "" {
filter = append(filter, bson.M{"description": params.Description})
}
but I got this error - cannot transform type []primitive.M to a BSON Document: WriteArray can only write a Array while positioned on a Element or Value but is positioned on a TopLevel
How do I solve this?
bson.M{} is underlined map[string]interface{} in go-mongo-driver. So if you need to add more elemnets, you can not append. Just assign that value to map's key as below.
filter := bson.M{}
if params.Title != "" {
//filter = bson.M{"title": params.Title}
filter["title"] = params.Title
}
if params.Description != "" {
filter["description"] = params.Description
}
Consider a collection test with a document: { "_id" : 1, "Title" : "t-1", "Description" : "d-1" }
And, you can use the following:
title := "t-1"
description := "" // or "d-1"
filter := bson.M{}
if Title != "" {
filter["Title"] = title
}
if Description != "" {
filter["Description"] = description
}
//fmt.Println(filter);
var result bson.M
collection := client.Database("test").Collection("test")
err := collection.FindOne(context.TODO(), filter).Decode(&result)
if err != nil {
log.Fatal(err)
}
fmt.Printf("Found a single document: %+v\n", result)
I'd like to get the names of all the keys in a MongoDB collection.
For example, from this:
"Id": ObjectId("5f5a010d431c4519dcda0e3d")
"title": "App"
"query": ""
"db": ""
"widgettype": ""
"tablename": "active_instance"
fields:Object
user:"name",
key:"passcode"
"status": "active"
"inlibrary": ""
"createdts": 1599733804
Using "gopkg.in/mgo.v2" and "gopkg.in/mgo.v2/bson" packages.
err := mongodbSession.DB(dbName).C(collectionName).Find(bson.M{}).One(&result)
var keyset []string
for index, _ := range result {
fmt.Printf("%+v\n", index)
keyset = append(keyset, index)
}
fmt.Println(keyset)
getting output as this
[_id title query db widgettype status fields inlibrary createdts ]
child key is not being featched that is user and key.
Embedded documents will appear as another bson.M values inside your result, so you have to use a recursion to also traverse those.
Here's how you can do that:
func getKeys(m bson.M) (keys []string) {
for k, v := range m {
keys = append(keys, k)
if m2, ok := v.(bson.M); ok {
keys = append(keys, getKeys(m2)...)
}
}
return
}
Example using it:
m := bson.M{"Id": bson.ObjectId("5f5a010d431c4519dcda0e3d"),
"title": "App",
"query": "",
"db": "",
"widgettype": "",
"tablename": "active_instance",
"fields": bson.M{
"user": "name",
"key": "passcode",
},
"status": "active",
"inlibrary": "",
"createdts": 1599733804,
}
keys := getKeys(m)
fmt.Println(keys)
Which will output (try it on the Go Playground):
[db widgettype createdts inlibrary _id title query tablename
fields user key status]
If you look at the results, user and key are included, but it's not possible to tell if they were fields of the document or that of an embedded document.
You may choose to prefix fields of embedded documents with the field name of the embedded document field itself, e.g. to get fields.user and fields.key.
This is how you can do that:
func getKeys(m bson.M) (keys []string) {
for k, v := range m {
keys = append(keys, k)
if m2, ok := v.(bson.M); ok {
for _, k2 := range getKeys(m2) {
keys = append(keys, k+"."+k2)
}
}
}
return
}
Which would output (try it on the Go Playground):
[createdts title query db status inlibrary _id widgettype tablename
fields fields.user fields.key]
Also note that the above solutions do not handle arrays. If you have arrays, you should also iterate over them, and if they contain another array or object, you should do the same (recursively). It's an exercise for you to extend it to handle arrays too.
How to retrieve multidimensional []bson.M type of map
The data in mongo is like
"taskData" : {
"createdOn" : ISODate("2016-02-20T21:23:11.903Z"),
"Task_content" : "#bob",
"Priority" : "2",
"owner_Uname" : "alice"
}
The code through which i tried to access it
var n []bson.M
e := collection.Find(bson.M{"users."+strconv.Itoa(j)+".user_name" : r.FormValue("value[userName]")}).Select(bson.M{"taskData.owner_Uname":1,"_id":0}).All(&n)
if e != nil {
fmt.Println("Error : ",e)
}else{
fmt.Println(n[0]["taskData"])
}
getting output like this
map[owner_Uname:alice]
I need to access this resultant string with another query.
It is a interface i tried to convert it to simple map
newMap :=n[0]["taskData"].(map[string]interface{})but it gives me an runtime error interface conversion: interface {} is bson.M, not map[string]interface {}
result := rawData{}
err := collection.Find(bson.M{"user_name":n[0]["taskData"]["owner_Uname"]}).All(&result)
Now I want to use it in above query ...
Kindly help me out. Thanks in advance
Edit :-
The data in mongo is like
{
"_id" : ObjectId("56bf128f5a9a6a0ebfdd5075"),
"deadLine" : {
"Start_time" : ISODate("2016-05-24T00:00:00Z"),
"End_time" : ISODate("2016-05-29T00:00:00Z")
},
},
"taskData" : {
"createdOn" : ISODate("2016-02-20T21:23:11.903Z"),
"Task_content" : "#bob",
"Priority" : "2",
"owner_Uname" : "alice"
},
"group" : {
"1" : {
"grp_name" : "grp"
},
"2" : {
"grp_name" : "secondGrp"
}
}
That will work me too if it is done with nested struct or map in struct
I'll provide you with a general example to help you understand, since SO is not a free coding service, but a platform where peers help each other to take a grasp on the problem.
My approach is not to use bson.M at all for the returned value.
package main
import (
"fmt"
"time"
"gopkg.in/mgo.v2"
"gopkg.in/mgo.v2/bson"
)
type Baz struct {
Date time.Time
Value int
}
type Bar struct {
Name string
Baz []Baz
}
type Foo struct {
Owner string
hidden int
Bar Bar
}
const (
ds = "localhost:27017"
db = "test"
coll = "nestdemo"
)
func main() {
o := Foo{
Owner: "me",
hidden: 1,
Bar: Bar{
Name: "funky",
Baz: []Baz{
Baz{Date: time.Now(), Value: 42},
},
},
}
// CHECK ERRORS in production environments
conn, _ := mgo.Dial(ds)
defer conn.Close()
c := conn.DB(db).C(coll)
c.Insert(o)
l := &Foo{}
c.Find(bson.M{"owner": "me"}).One(l)
fmt.Printf("Loaded data: %+v\n", l)
fmt.Printf(
"You got your answer to life, the universe and all the rest at %s: %d\n",
l.Bar.Baz[0].Date.Format(time.Kitchen), l.Bar.Baz[0].Value,
)
}
You can run this program on you local machine (with the constants adjusted as needed), which should give you an output looking like this:
$ go run main.go
Loaded data: &{Owner:me hidden:0 Bar:{Name:funky Baz:[{Date:2016-02-24 09:00:06.471 +0100 CET Value:42}]}}
You got your answer to life, the universe and all the rest at 9:00AM: 42
The entry in the according collection should read something like this:
{
"_id" : ObjectId("56cd6306538ba56563bdab76"),
"owner" : "me",
"bar" : {
"name" : "funky",
"baz" : [
{
"date" : ISODate("2016-02-24T08:00:06.471Z"),
"value" : 42
}
]
}
}
A few things are to note here.
I didn't need a single character in my struct definitions to have the structs marshaled to and marshaled from BSON. It was done automagically by mgo according to the rules described in the docs. However, you can customize the behavior of the (un-)marshaling, as described there.
Unexported fields (hidden in this example) take their zero value upon unmarshalling – keep that in mind, it can bite you in the neck.
There is no need to use bson.M to handle your data, which makes life a lot easier – no manual type conversions, for example.
In summary: All you need to do is to create a struct your data can be unmarhaled into. Then you can access the various fields as usual, without string fiddling and alike. That's bit of work, but a rather trivial one, as you can see.
Note: The data model you have shown is both syntactically and conceptually incorrect. Setting aside the former for now: It is a very bad practice to have values as keys, as shown in the group subdoc. This will always force you to deal with string parsing back and forth, making your life with MongoDB as complicated as it can get as a developer.
My above suggestion assumes you will correct that into something like:
{
…
groups:[
{grp_id: 1, grp_name: "grp"},
{grp_id: 2, grp_name: "secondGrp"}
]
…
}
I have a document which has this following structure
{ "_id" : "736722976", "value" : { "total_visit" : 4, "FIFA World Cup 2014" : 1, "Germany" : 1, "Algeria" : 1, "Thomas Muller" : 1, "Mesut Ozil" : 1, "Monsoon" : 1, "India Meteorological Department (IMD)" : 1, "Web Exclusive" : 2, "Specials" : 1, "Tapas Pal" : 1, "Twitter Trends" : 1, "Sunanda Pushkar" : 1, "Shashi Tharoor" : 1, "AIIMS" : 1, "special" : 1 } }
THE MOST IMPORTANT thing is that the sub document structure under the key "value" is variable so I can not create a structure for that. I tried to follow the suggestion here - Unstructured MongoDB collections with mgo
And I came with this code ---
package main
import ("fmt"
"labix.org/v2/mgo" //importing mgo
"labix.org/v2/mgo/bson"
_ "reflect"
)
type AnalysisStruct struct{
Id string `bson:"_id,omitempty"`
Value bson.M `bson:",inline"`
}
func main() {
var m AnalysisStruct
//connecting to localhost mongodb
session, err := mgo.Dial("localhost")
if err != nil {
panic(err)
}
defer session.Close()
c := session.DB("my_analysis_db").C("analysis_mid_2")
iter := c.Find(nil).Iter()
for{
if iter.Next(&m){
fmt.Println(m.Value["value"]["total_visit"])
}else{
break
}
}
}
When I try to build this using go build -v -o analyzer it shows me this error---
./analyzer.go:32: invalid operation: m.Value["value"]["total_visit"] (index of type interface {})
I am terribly stuck with this. Can not get anything going. Please can somebody help?
Thanks
I cam up with this code after doing some research. Not the most optimized one for sure. But for my case it works. Took help from
http://blog.denevell.org/golang-interface-type-assertions-switch.html
https://groups.google.com/forum/#!topic/mgo-users/JYE-CP15az4
package main
import ("fmt"
"labix.org/v2/mgo" //importing mgo
"labix.org/v2/mgo/bson"
_ "reflect"
)
type AnalysisStruct struct{
Id string `bson:"_id,omitempty"`
Value bson.M `bson:",inline"`
}
func main() {
var m AnalysisStruct
//connecting to localhost mongodb
session, err := mgo.Dial("localhost")
if err != nil {
panic(err)
}
defer session.Close()
c := session.DB("consumergenepool_db").C("analysis_mid_2")
iter := c.Find(nil).Iter()
for{
if iter.Next(&m){
s := m.Value["value"].(bson.M)
data, _ := bson.Marshal(s)
var m bson.M
_ = bson.Unmarshal(data, &m)
fmt.Println(m)
for k, v := range m{
fmt.Print(k)
fmt.Print(" :: ")
fmt.Println(v)
}
}else{
break
}
}
}
Let me know your thoughts on this.
Thanks
When testing something new always use a lot of fmt.Printf's to get a feel for it, that being said.
Value bson.M `bson:",inline"`
Should be
Value bson.M `bson:"value,omitempty"`
And
fmt.Println(m.Value["value"]["total_visit"])
Should be:
fmt.Printf("%#v\n", m)
fmt.Println(m.Value["total_visit"])
Your m.Value is "value", so you can use m.Value["total_visit"] directly.
playground
//edit
You can only use inline to catch any fields that that aren't a part of the original struct, but since your struct only has 2 fields (Id and Value), you don't need it.
Now if you were to keep ,inline you would use it like this:
if v, ok := m.Value["value"].(bson.M); ok {
fmt.Println(v["total_visit"])
}
Because m.Value["value"] is an interface{}, you have to type assert it back to it's original value, bson.M before you could use it.