DynamoDB-过滤表达式

• 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：

{
    "success": {
        "Items": [
            {
                "date": "2010-01-01",
                "author": "韩寒",
                "price": 55.55,
                "zan": 520,
                "count": 10,
                "name": "三重门",
                "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。",
                "id": "05d101be-d5e8-43ec-8eb6-5530e21af83e",
                "sn": "100-100-010",
                "type": "情感其他",
                "uri": "https://www.cnblogs.com/landen/p/9790704.html ",
                "hash": "book"
            },
            {
                "date": "2010-01-01",
                "author": "韩寒",
                "price": 99.99,
                "count": 8,
                "name": "三重门",
                "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。",
                "id": "4b99e00f-9f57-41f7-80de-d581e8c84522",
                "sn": "100-100-100",
                "type": "情感其他",
                "hash": "book"
            },
            {
                "date": "2010-01-01",
                "author": "韩寒",
                "price": 23.5,
                "count": 7,
                "name": "三重门",
                "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。",
                "id": "5ed6bce8-3ffb-46c8-bc04-04b31d922fd8",
                "sn": "100-100-008",
                "type": "情感其他",
                "hash": "book"
            },
            {
                "date": "2010-01-01",
                "author": "韩寒",
                "price": 23.5,
                "name": "三重门",
                "count": 7,
                "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。",
                "id": "6f1e4501-f2ba-499f-a2ad-d1173adc062a",
                "sn": "100-100-008",
                "type": "情感其他",
                "hash": "book"
            },
            {
                "date": "2010-01-01",
                "author": "韩寒",
                "price": 23.5,
                "name": "三重门",
                "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。",
                "id": "898a4f74-648d-4996-8ff9-3395c668d506",
                "sn": "100-100-008",
                "type": "情感其他",
                "hash": "book"
            },
            {
                "date": "2010-01-01",
                "author": "韩寒",
                "price": 103.5,
                "name": "三重门",
                "count": 7,
                "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。",
                "id": "8baff9a7-179b-46b3-801d-5e7b9abd3dfe",
                "sn": "100-100-008",
                "type": "情感其他",
                "hash": "book"
            },
            {
                "date": "2010-01-01",
                "author": "韩寒",
                "price": 103.5,
                "name": "三重门",
                "count": 7,
                "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。",
                "id": "960eb7c2-5ac1-4e9a-859e-31c2c8754972",
                "sn": "100-100-008",
                "type": "情感其他",
                "hash": "book"
            }
        ],
        "Count": 7,
        "ScannedCount": 10,
        "LastEvaluatedKey": {
            "hash": "book",
            "id": "9787540475581"
        }
    }
}

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