MongoDB 連線插入刪除更新查詢

package main

import (
    "fmt"
    "time"

    log "github.com/Sirupsen/logrus"
    mgo "gopkg.in/mgo.v2"
    "gopkg.in/mgo.v2/bson"
)

var mongoConn *mgo.Session

type MongoDB_Conn struct {
    Host string `json:"Host"`
    Port string `json:"Port"`
    User string `json:"User"`
    Pass string `json:"Pass"`
    DB   string `json:"DB"`
}

func MongoConn(mdb MongoDB_Conn) (*mgo.Session, string, error) {
    if mongoConn != nil {
        if mongoConn.Ping() == nil {
            return mongoConn, nil
        }
    }
    user := mdb.User
    pass := mdb.Pass
    host := mdb.Host
    port := mdb.Port
    db := mdb.DB
    if host == "" || port == "" || db == "" {
        log.Fatal("Host or port or db is nil")
    }
    url := fmt.Sprintf("mongodb://%s:%s@%s:%s/%s", user, pass, host, port, db)
    if user == "" {
        url = fmt.Sprintf("mongodb://%s:%s/%s", host, port, db)
    }
    mongo, err := mgo.DialWithTimeout(url, 3*time.Second)
    if err != nil {
        log.Errorf("Mongo Conn Error: [%v], Mongo ConnUrl: [%v]",
            err, url)
        errTextReturn := fmt.Sprintf("Mongo Conn Error: [%v]", err)
        return &mgo.Session{}, errors.New(errTextReturn)
    }
    mongoConn = mongo
    return mongoConn, nil
}

func MongoInsert(dbName, C string, data interface{}) error {
    mongo, err := MongoConn()
    if err != nil {
        log.Error(err)
        return err
    }
    db := mongo.DB(dbName)
    collection := db.C(C)
    err = collection.Insert(data)
    if err != nil {
        return err
    }
    return nil
}

func MongoRemove(dbName, C string, selector bson.M) error {
    mongo, err := MongoConn()
    if err != nil {
        log.Error(err)
        return err
    }
    db := mongo.DB(dbName)
    collection := db.C(C)
    err = collection.Remove(selector)
    if err != nil {
        return err
    }
    return nil
}

func MongoFind(dbName, C string, query, selector bson.M) ([]interface{}, error) {
    mongo, err := MongoConn()
    if err != nil {
        return nil, err
    }
    db := mongo.DB(dbName)
    collection := db.C(C)
    result := make([]interface{}, 0)
    err = collection.Find(query).Select(selector).All(&result)
    return result, err
}

func MongoUpdate(dbName, C string, selector bson.M, update interface{}) error {
    mongo, err := MongoConn()
    if err != nil {
        log.Error(err)
        return err
    }
    db := mongo.DB(dbName)
    collection := db.C(C)
    err = collection.Update(selector, update)
    if err != nil {
        return err
    }
    return nil
}