如何使用 GraphQL 和 Mongodb 编写 lambda 函数？

Posted 2023-03-08

【中文标题】如何使用 GraphQL 和 Mongodb 编写 lambda 函数？

【英文标题】：How to write lambda function using GraphQL and Mongodb?

【发布时间】：2019-12-24 18:33:51

【问题描述】：

我是新的 GraphQL，我阅读了有关 GraphQL 的文章，它与我的预期相似，但我不明白如何在 aws lambda 函数中使用它。我有两个集合 1）user_posts 2）user_profile。查找以下收集数据供您参考。

1) user_posts 集合

_id :ObjectId("5d519f861c9d4400005ebd1b")
userid : ObjectId("5d518caed55bc00001d235c1")
media : "hello.jpg"
type : "jpg"
created : " "
modified : " "
like : Array
       0 : Object
           userid : ObjectId("5d518caed55bc00001d235c1")
           status : "like"
       1 : Object
           userid : ObjectId("5d518da6d55bc00001d235c2")
           status : "happy"
comment : Array
       0 : Object
           userid : ObjectId("5d518caed55bc00001d235c1")
           comment : "hello"
       1 : Object
           userid : ObjectId("5d518da6d55bc00001d235c2")
           comment : "welcome"
share : Array
       0 : Object
           userid : ObjectId("5d518caed55bc00001d235c1")
           status : "shared"
       1 : Object
           userid : ObjectId("5d518da6d55bc00001d235c2")
           status : "shared"

2) User_profile 集合

 _id : ObjectId("5d518caed55bc00001d235c1")
 username : "ramesh",
 photo :  " ",
 created : " ",
 modified : " "

 _id : ObjectId("5d518da6d55bc00001d235c2")
 username : "shekar",
 photo :  " ",
 created : " ",
 modified : " "

通常我使用 lambda 函数来获得这样的输出。但它没有得到我预期的输出。

var MongoClient = require('mongodb').MongoClient;
var ObjectId = require('mongodb').ObjectID;
var databasename = "trans_db";
var db;

exports.handler = (event, context, callback) => 

 var Userid = event['userid'];
 var uid = ObjectId(Userid);

 MongoClient.connect(uri, useNewUrlParser: true , (error, client) => 
 if (error) return 1;    // Checking the connection
 console.log('Connection Successful');
 db = client.db(databasename);

 db.collection("user_posts").find("userid" : uid).toArray(function(err, 
 res) 
    if (err) throw err;

    context.succeed(res);
    );
  );
  ;

我需要下面这样的输出。

_id :ObjectId("5d519f861c9d4400005ebd1b")
userid : ObjectId("5d518caed55bc00001d235c1")
username : "ramesh"
photo : " ",
media : "hello.jpg"
type : "jpg"
created : " "
modified : " "
like : Array
       0 : Object
           userid : ObjectId("5d518caed55bc00001d235c1")
           status : "like"
           username : "ramesh"
           photo : " "
       1 : Object
           username : "shekar"
           photo : " "
           userid : ObjectId("5d518da6d55bc00001d235c2")
           status : "happy"
           username : "shekar"
           photo : " "
comment : Array
       0 : Object
           userid : ObjectId("5d518caed55bc00001d235c1")
           comment : "hello"
           username : "ramesh"
           photo : " "
       1 : Object
           userid : ObjectId("5d518da6d55bc00001d235c2")
           comment : "welocme"
           username : "shekar"
           photo : " "
share : Array
       0 : Object
           userid : ObjectId("5d518caed55bc00001d235c1")
           status : "shared"
           username : "ramesh"
           photo : " "
       1 : Object
           userid : ObjectId("5d518da6d55bc00001d235c2")
           status : "shared"
           username : "shekar"
           photo : " "

【问题讨论】：

您的 MongoDB 版本是多少？为什么不使用猫鼬？

@Ashok 我正在使用 mongodb 地图集

【参考方案1】：

您需要 mongo min 3.6 版。

根据user_posts 更新您的架构基础以获取下面的查询。

MongoDB查询

 MongoClient.connect(uri, useNewUrlParser: true , (error, client) => 
    if (error) return 1;    // Checking the connection
    console.log('Connection Successful');
    db = client.db(databasename);
    db.collection("user_posts").aggregate(
     $match: "userid" : uid,
     $unwind: '$like' ,
     $lookup:  from: "users", localField: "like.userid", foreignField: "_id", as: "users" ,
     $group: 
        _id: "$_id",
        like:  $push:  $mergeObjects: ['$like',  $arrayElemAt: [ "$users", 0 ]  ],
        data:  $first: "$$ROOT" 
    ,
     $replaceRoot:  newRoot:  $mergeObjects: ['$data',  like: "$like" ]  
     $unwind: '$comment' ,
     $lookup:  from: "users", localField: "comment.userid", foreignField: "_id", as: "users" ,
     $group: 
        _id: "$_id",
            comment:  $push:  $mergeObjects: ['$comment',  $arrayElemAt: [ "$users", 0 ]  ],
            data:  $first: "$$ROOT" 
    ,
     $replaceRoot:  newRoot:  $mergeObjects: ['$data',  comment: "$comment" ]  
     $unwind: '$share' ,
     $lookup:  from: "users", localField: "share.userid", foreignField: "_id", as: "users" ,
     $group: 
        _id: "$_id",
        share:  $push:  $mergeObjects: ['$share',  $arrayElemAt: [ "$users", 0 ]  ],
        data:  $first: "$$ROOT" 
    ,
     $replaceRoot:  newRoot:  $mergeObjects: ['$data',  share: "$share" ]  ,
     $project:  users: 0 
    ).then(res => 
       context.succeed(res);
    ).catch(error => 
       console.log( error )
    );

GraphQL

 user_posts 
     _id
    userid
    username
    photo 
    media
    type 
    created
    modified 
    like 
        userid
        username
        status
        photo 
    
    comment 
        userid
        username
        status
        photo 
    
    share 
        userid
        username
        status
        photo 
    
 

graphql 中解析器的变化基于 graphql 中的查询，我们可以简化 mongodb 查询，但现在我们必须专注于 Graphql

【讨论】：

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