如何使用 GraphQL 和 Mongodb 编写 lambda 函数？

Question

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 : " "

Answer 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