How to scan in DynamoDB without primary sort key with Nodejs

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:

I updated the code. I got the error: MultipleValidationErrors: There were 2 validation errors: * UnexpectedParameter: Unexpected key 'KeyConditionExpression' found in params * InvalidParameterType: Expected params.ExpressionAttributeValues[':sync'] to be a structure — John
– John, Commented Apr 13, 2021 at 1:04
Oh sorry. Now i get this error: UnexpectedParameter: Unexpected key 'KeyConditionExpression' found in params — John
– John, Commented Apr 13, 2021 at 1:13

Jason Wadsworth · Accepted Answer · 2021-04-13 02:52:08Z

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){ ... }

answered Apr 13, 2021 at 2:52

Jason Wadsworth

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