DynamoDB-过滤表达式

Posted 2021-01-13 曦言鸢默

• contains (path, operand)

case \'GET\': {

            var next = null;
            if( event.queryStringParameters && event.queryStringParameters.next ){
                next = JSON.parse( event.queryStringParameters.next );
            }
            console.log( next );

            var params = {
                TableName: "book_table",
                KeyConditionExpression: "#key = :value",
                //contains(path, operand)
                 FilterExpression: "contains(#n, :n) and #p < :p",
                ExpressionAttributeNames: {
                    "#key": "hash",
                    "#n": "name",
                    "#p": "price"
                },
                ExpressionAttributeValues: {
                    ":p": 188.88,
                    ":n": "三重门",
                    ":value": "book"
                },
                Limit: 10
            };

            if( next ){
                params = {...params, ExclusiveStartKey: next.LastEvaluatedKey };
            }
        
            await docClient.query( params ).promise().then(
                ( data ) => {
                    response.body = JSON.stringify({ "success": data });
                    callback( null, response );
                }
            ).catch(
                ( err ) => {
                    response.statusCode = err.statusCode;
                        response.body = JSON.stringify({
                            code: err.code,
                            message: err.message
                        });
                        callback( null, response );
                }
            )
            break;
        }

程序运行成功后返回：

 1 {
 2     "success": {
 3         "Items": [
 4             {
 5                 "date": "2010-01-01",
 6                 "author": "韩寒",
 7                 "price": 55.55,
 8                 "zan": 520,
 9                 "count": 10,
10                 "name": "三重门",
11                 "description": "本书通过少年林雨翔的视角，向读者揭示了真实的高中生的生活，体现了学生式的思考、困惑和梦想。",
12                 "id": "05d101be-d5e8-43ec-8eb6-5530e21af83e",
13                 "sn": "100-100-010",
14                 "type": "情感其他",
15                 "uri": "https://www.cnblogs.com/landen/p/9790704.html ",
16                 "hash": "book"
17             },
18             {
19                 "date": "2010-01-01",
20                 "author": "韩寒",
21                 "price": 99.99,
22                 "count": 8,
23                 "name": "三重门",
24                 "description": "本书通过少年林雨翔的视角，向读者揭示了真实的高中生的生活，体现了学生式的思考、困惑和梦想。",
25                 "id": "4b99e00f-9f57-41f7-80de-d581e8c84522",
26                 "sn": "100-100-100",
27                 "type": "情感其他",
28                 "hash": "book"
29             },
30             {
31                 "date": "2010-01-01",
32                 "author": "韩寒",
33                 "price": 23.5,
34                 "count": 7,
35                 "name": "三重门",
36                 "description": "本书通过少年林雨翔的视角，向读者揭示了真实的高中生的生活，体现了学生式的思考、困惑和梦想。",
37                 "id": "5ed6bce8-3ffb-46c8-bc04-04b31d922fd8",
38                 "sn": "100-100-008",
39                 "type": "情感其他",
40                 "hash": "book"
41             },
42             {
43                 "date": "2010-01-01",
44                 "author": "韩寒",
45                 "price": 23.5,
46                 "name": "三重门",
47                 "count": 7,
48                 "description": "本书通过少年林雨翔的视角，向读者揭示了真实的高中生的生活，体现了学生式的思考、困惑和梦想。",
49                 "id": "6f1e4501-f2ba-499f-a2ad-d1173adc062a",
50                 "sn": "100-100-008",
51                 "type": "情感其他",
52                 "hash": "book"
53             },
54             {
55                 "date": "2010-01-01",
56                 "author": "韩寒",
57                 "price": 23.5,
58                 "name": "三重门",
59                 "description": "本书通过少年林雨翔的视角，向读者揭示了真实的高中生的生活，体现了学生式的思考、困惑和梦想。",
60                 "id": "898a4f74-648d-4996-8ff9-3395c668d506",
61                 "sn": "100-100-008",
62                 "type": "情感其他",
63                 "hash": "book"
64             },
65             {
66                 "date": "2010-01-01",
67                 "author": "韩寒",
68                 "price": 103.5,
69                 "name": "三重门",
70                 "count": 7,
71                 "description": "本书通过少年林雨翔的视角，向读者揭示了真实的高中生的生活，体现了学生式的思考、困惑和梦想。",
72                 "id": "8baff9a7-179b-46b3-801d-5e7b9abd3dfe",
73                 "sn": "100-100-008",
74                 "type": "情感其他",
75                 "hash": "book"
76             },
77             {
78                 "date": "2010-01-01",
79                 "author": "韩寒",
80                 "price": 103.5,
81                 "name": "三重门",
82                 "count": 7,
83                 "description": "本书通过少年林雨翔的视角，向读者揭示了真实的高中生的生活，体现了学生式的思考、困惑和梦想。",
84                 "id": "960eb7c2-5ac1-4e9a-859e-31c2c8754972",
85                 "sn": "100-100-008",
86                 "type": "情感其他",
87                 "hash": "book"
88             }
89         ],
90         "Count": 7,
91         "ScannedCount": 10,
92         "LastEvaluatedKey": {
93             "hash": "book",
94             "id": "9787540475581"
95         }
96     }
97 }

View Code

本文为原创，还望指教！

若有疑问，可在下方留言，也可自读AWS官方文档——DynamoDB：https://docs.aws.amazon.com/zh_cn/amazondynamodb/latest/developerguide/Expressions.ExpressionAttributeValues.html