DynamoDB query shows UnepectedParameter - aws-lambda

Question

I'm trying to create a query in Lambda for a DynamoDB table.
I have followed the Instructions and examples from the aws developer handbook but still get an error
//+++++++++++++++++++++++++++++++++++++++++++
//The database Structure
"Table": {
"AttributeDefinitions": [
{
"AttributeName": "Score",
"AttributeType": "N"
},
{
"AttributeName": "gtin_RecBook",
"AttributeType": "S"
},
{
"AttributeName": "gtin_RefBook",
"AttributeType": "S"
}
],
"TableName": "Recommendation_test_2",
"KeySchema": [
{
"AttributeName": "gtin_RefBook",
"KeyType": "HASH"
},
{
"AttributeName": "gtin_RecBook",
"KeyType": "RANGE"
}
]
}
//+++++++++++++++++++++++++++++++++++++++++++
// The Lambda Code
const AWS = require('aws-sdk');
const dynamodb = new AWS.DynamoDB({region:'eu-central-1', apiVersion:'2012-08-10'});
exports.handler = (event, context, callback) => {
const params = {
TableName: "Recommendation_test_2",
KeyConditionExpression: "gtin_RefBook = :a",
ExpressionAttributeValues: {
":a": "9783453471092"
}
};
dynamodb.query(params, function(err, data){
if (err) {
console.log(err);
callback(err);
} else{
console.log(data);
callback(null, data);
}
});
};
The database is populated and should provide some results.
However Lambda throws the following error:
"errorMessage": "There were 14 validation errors:\n* InvalidParameterType: Expected params.ExpressionAttributeValues[':a'] to be a structure"
Could you please tell me what to change to make the query work?

Answer 1

You need to use the DynamoDB Document Client or change the ExpresionAttributeValue to
ExpressionAttributeValues: {
":a": {
"S": "9783453471092"
}
}