使用NodeJS将新对象附加到DynamoDB中的JSON数组 [英] Append a new object to a JSON Array in DynamoDB using NodeJS

问题描述

我正在使用JSON结构存储一个人的详细信息。基本上，名称，电话，registeredTimestamp等将是其他属性，主键将是电子邮件地址。

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，受访位置，searchHistory和推荐是列表或地图正如AWS所称。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"
        }
    ]
}

在应用中，如果用户访问了新位置，我需要向 markedLocations 添加一个新的JSON对象。
因此，markedLocations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}
    };

我检查了-

• 在DynamoDB中，如何使用Java 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数据库中更新集合链接

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 。我没有发现与我的问题/疑问有关的任何东西。

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中用新的JSON对象附加JSON数组？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.

OR

我应该为每个数组创建一个单独的表，并将电子邮件作为主键，将时间戳作为排序键然后继续吗？

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，我与MongoDB较早，那里有使用JSON数组和对象的方法。

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（） 一起在 UpdateExpression 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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