电子邮件

manaf1@gmail.com

manaf2@gmail.com

manaf3@gmail.com

然后，我尝试用新密钥更新表格＆＃34;详细信息＆＃34;它的值是一个列表。这是我的代码

var AWS = require("aws-sdk");

var params =
    {
        TableName: "manaftable1",
        Key: { email: "manaf1@gmail.com" },
        UpdateExpression: "set #details = list_append (#details, :detailsinput)",
        ExpressionAttributeNames: {
            "#details": "details"
        },
        ExpressionAttributeValues: {
            ":detailsinput":{ "id": "1","mob": "978956" }
        }
    };


var docClient = new AWS.DynamoDB.DocumentClient();

docClient.update(params, function (err, data) {
    if (err)
        console.log(JSON.stringify(err, null, 2));
    else
        console.log(JSON.stringify(data, null, 2));
});

但是我得到了这样的错误

{
  "message": "Invalid UpdateExpression: Incorrect operand type for operator or function; operator or function: list_append, operand type: M",
  "code": "ValidationException",
  "time": "2016-10-26T11:04:60.756",
  "requestId": "SN0NPRHDFHUKBBJHOVI0DFHHRQNSO5AEMVJFFGHF9ASFHUAAJG",
  "statusCode": 400,
  "retryable": false,
  "retryDelay": 0
}

我需要在更新后像这样回复

column1：email

第2栏：详情

manaf1@gmail.com |   [{＆＃34; ID＆＃34;：＆＃34; 1＆＃34;＆＃34;暴民＆＃34;：＆＃34; 978956＆＃34;}，{＆＃34; ID＆＃34;：＆＃34; 2＆＃34;＆＃34;暴民＆＃34;：＆＃34; 767886＆＃34;}]

manaf2@gmail.com |

与我的代码相关的问题是什么？

Answer 1

作为list_append says的AWS文档：

新元素必须包含在列表中，例如将2添加到a 列表，操作数将是[2]

所以你需要追加一个对象数组，而不仅仅是一个对象：

var params =
    {
        TableName: "manaftable1",
        Key: { email: "manaf1@gmail.com" },
        UpdateExpression: "set #details = list_append (#details, :detailsinput)",
        ExpressionAttributeNames: {
            "#details": "details"
        },
        ExpressionAttributeValues: {
            ":detailsinput": [{ "id": "1","mob": "978956" }]
        }
    };

如果对象中不存在该属性，则可以使用if_not_exists操作数：

var params =
    {
        TableName: "manaftable1",
        Key: { email: "manaf1@gmail.com" },
        UpdateExpression: "set if_not_exists(#details, []) set #details = list_append (#details, :detailsinput)",
        ExpressionAttributeNames: {
            "#details": "details"
        },
        ExpressionAttributeValues: {
            ":detailsinput": [{ "id": "1","mob": "978956" }]
        }
    };

Answer 2

当项目中存在details属性为 NOT 时，更新表达式应该只有SET而没有list_append。

UpdateExpression : "SET #details = :details"

当商品中的details属性存在且新更新需要在列表中添加其他元素时，list_append可用于添加新元素列表。

UpdateExpression : "set #details = list_append (#details, :details)"

Answer 3

同时使用list_append()和if_not_exists()附加到可能不存在的列表列：

var params = {
  TableName: "manaftable1",
  Key: { email: "manaf1@gmail.com" },
  UpdateExpression: "set #details = list_append(if_not_exists(#details, :empty_list), :detailsinput)",
  ExpressionAttributeNames: {
    "#details": "details"
  },
  ExpressionAttributeValues: {
    ":detailsinput": [{ "id": "1","mob": "978956" }],
    ":empty_list": []
  }
};

使用node.js更新表达式的dynamo db错误

电子邮件

3 个答案: