How to Query a Array of objects in DynamoDB using FilterExpression in scan operation

问题

How to Query array of objects(workingDays) key containing only "Tue" in dynamoDb with Scan Operation,I have queried using filter Expression but i am getting no results.

var queryData = {
        TableName: tableName,
        FilterExpression: "contains (workingDays, :dayVal)",
        ExpressionAttributeValues: {
            ":dayVal": {
                S:"Tue"
            }
        }
    };

    console.log("getParams ==>", queryData)
    dynamodb.scan(queryData, function (err, details) {
        if (err) {
            console.log(err, err.stack); // an error occurred
            callback(err, null)
        }
        else{
           callback(null, details)

        }
    })

回答1:

ExpressionAttributeValues in your query contains String ["S"] as 'key' for value 'Tue', where as in your table, 'workingDays' is a list of map object containing value for day keys.

Try below code:

var queryData = {
    TableName: tableName,
    ExpressionAttributeNames: {
         "#workingDays": "workingDays",
    },
    FilterExpression: "contains (#workingDays, :dayVal)",
    ExpressionAttributeValues: {
      ":dayVal": {
          "day":"Tue"
      }
   }
};

console.log("getParams ==>", queryData)

docClient.scan(queryData, function (err, details) {
    if (err) {
        console.log(err, err.stack); // an error occurred
       // callback(err, null)
    }
    else{
       // callback(null, details)
       console.log(details);
   }
});

来源：https://stackoverflow.com/questions/54002458/how-to-query-a-array-of-objects-in-dynamodb-using-filterexpression-in-scan-opera