如何在没有主排序键的情况下使用 Nodejs 在 DynamoDB 中进行扫描

Question

I'm trying to scan in DynamoDB without primary sort key with Nodejs. I have the following Table

var params = {
    AttributeDefinitions: [
        {
        AttributeName: "barname",
        AttributeType: "S"
        },
        {
        AttributeName: "timestamp",
        AttributeType: "S"
        }
    ],
    KeySchema: [
        {
        AttributeName: "barname",
        KeyType: "HASH"
        },
        {
        AttributeName: "timestamp",
        KeyType: "RANGE"
        }
    ],
    ProvisionedThroughput: {
        ReadCapacityUnits: 1,
        WriteCapacityUnits: 1
    },
    TableName: tableName
};

I put with two objects:

data1 = {
    barname: "paul",
    timestamp: new Date().toISOString(),
    sync: false,
    number : "1234",
}

data2 = {
    barname: "john",
    timestamp: new Date().toISOString(),
    sync: true,
    number : "333",
}

How to scan all objects that barname = 'john' and sync = true?

I tried something like that:

var params = {
    TableName: tableName,
    FilterExpression: "sync = :sync and barname = :barname",
    ExpressionAttributeValues: {
        ':barname' : {S: 'john'},
        ':sync' : {BOOL: true}
      },
  };

  dynamodb.scan(params, function(err, data){ ... }

The scan doesn't find anything:

{ Items: [], Count: 0, ScannedCount: 4 }

But i have 2 objects that match:

Answer 1

The error you are getting is because you are using the DynamoDB.DocumentClient , but you are specifying the full attribute type in the filter expression. If you just change the expression to not include the type it should work. I won't go into why this is probably a bad idea (scanning).

var params = {
    TableName: tableName,
    FilterExpression: "sync = :sync and barname = :barname",
    ExpressionAttributeValues: {
        ':barname' : 'john',
        ':sync' : true
      },
  };

  dynamodb.scan(params, function(err, data){ ... }