使用 NodeJS 将新对象附加到 DynamoDB 中的 JSON 数组

问题描述

我正在使用 JSON 结构来存储一个人的详细信息.基本上姓名、电话、注册时间戳等都是其他属性，主键是电子邮件地址.

I am using a JSON structure to store details of a person. Basically name, phone, registeredTimestamp etc., will be other attributes, and Primary key will be the email address.

markedLocations、visitedLocations、searchHistory 和推荐是 AWS 所称的列表或地图.它将包含许多 JSON 对象.

markedLocations, visitedLocations, searchHistory and recommendation are the lists or Map as AWS calls it. It will contain many JSON objects.

JSON 结构-

{
    "name":"Mama Miya",
    "phone":"9383883223",
    "registeredTimestamp":"some-time",
    "lastActiveTimestamp":"some-time",
    "signinType":"facebook",
    "additionalSigninData":{
        "key1":"value1",
        "key2":"value2"
    },
    "markedLocations":[
        {
            "latitude":"77.33",
            "longitude":"12.33",
            "name":"Home",
            "description":"my new home",
            "placeid":"55334433",
            "image":"url/abc.png"
        }
    ]
}

从应用程序中，如果用户访问一个新位置，我需要将一个新的 JSON 对象添加到 markedLocations.所以标记的位置应该看起来像-

From the app, if the user visits a new location, I need to add a new JSON Object to the markedLocations. So the markedLocations should look something like-

"markedLocations":[
    {
        "latitude":"77.33",
        "longitude":"12.33",
        "name":"Home",
        "description":"my new home",
        "placeid":"55334433",
        "image":"url/abc.png"
    },{
        "latitude":"22.11",
        "longitude":"22.55",
        "name":"Ocean",
        "description":"Ocean",
        "placeid":"32423423",
        "image":"url/icean.png"
    }
]

代码/架构-

var item = {
        'email': {'S': req.body.email},
        'phone': {'S': req.body.phone},
        'registeredTimestamp': {'S': req.body.registeredTimestamp},
        'lastActiveTimestamp': {'S': req.body.lastActiveTimestamp},
        'signinType': {'S': req.body.signinType},
        'version': {'S': req.body.version},
        'markedLocations': {'L': req.body.markedLocations}
    };

我查过了-

• 在 DynamoDB 中，如何使用 Java 将元素附加到列表字段 链接

在 AWS dynamoDB 中更新 JSON 数组链接

updating a JSON array in AWS dynamoDB link

使用 Node Js 在 Dynamo db 中更新 Set 链接

Updating a Set in Dynamo db using Node Js link

如何使用 nodejs 更新 dynamoDB 中的项目?链接

how to update item in dynamoDB using nodejs? link

并检查了 AWS 文档中的 UpdateItem API.我没有找到任何与我的问题/疑问相关的内容.

And checked AWS docs for UpdateItem API. I didn't find anything relevant to my problem/doubt.

请告诉我是否有办法在 NodeJS 中将 JSON 数组附加到一个新的 JSON 对象?我无法继续执行相同的操作.

Please can you tell me if there is a way to append the JSON array with a new JSON object in NodeJS? I am not able proceed on how to implement the same.

或

我是否应该为每个数组创建单独的表，并将电子邮件作为主键，将时间戳作为排序键并继续?

Should I create separate table for each Array and have email as primary key and timestamp as sort key and proceed?

PS:我是 DynamoDB 的新手，我之前使用过 MongoDB，并且有一些方法可以使用那里的 JSON 数组和对象.在这里找不到路.

PS: I am new to DynamoDB, I've worked with MongoDB earlier and there are ways to work with JSON arrays and objects there. Unable to find a way here.

推荐答案

使用 list_append() 和 if_not_exists() 在 UpdateExpression 以附加到可能不存在的列表列:

Use list_append() and if_not_exists() together in an UpdateExpression to append to a potentially non-existent list column:

var AWS = require('aws-sdk')
var DB = new AWS.DynamoDB.DocumentClient()

function appendMarkedLocation (personId, location) {
  return DB.update({
    TableName: 'people',
    Key: { id: personId },
    ReturnValues: 'ALL_NEW',
    UpdateExpression: 'set #markedLocations = list_append(if_not_exists(#markedLocations, :empty_list), :location)',
    ExpressionAttributeNames: {
      '#markedLocations': 'markedLocations'
    },
    ExpressionAttributeValues: {
      ':location': [location],
      ':empty_list': []
    }
  }).promise()
}

appendMarkedLocation('somePeronId', {
  latitude: '22.11',
  longitude: '22.55',
  name: 'Ocean',
  description: 'Ocean',
  placeid: '32423423',
  image: 'url/icean.png'
}).then(console.log)

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