Dynamodb alexa query not calling data item - node.js

Question

I am creating a skill where I want to call alexa to read differnt items at certain dates and times.
I currently have my table set up as follows:
Date|Time|State
Date is setup as my primary key with time as my sort key. I have setup date and time as slot values in ASK, and I can see that these values are being passed through. I have also made sure the format of my date and time is correct within dynamodb.
My issue is when I call alexa and ask for the state at a certain date and time, I can't get alexa to respond with the state corresponding with that date and time.
Can anyone help me with this? Or tell me where i'm going wrong, I will insert my code below.
const awsSDK = require('aws-sdk');
const updatedincident = 'updatedincident';
const docClient = new awsSDK.DynamoDB.DocumentClient();
var AWSregion = 'us-east-1'; // us-east-1
var AWS = require('aws-sdk');
var dbClient = new AWS.DynamoDB.DocumentClient();
AWS.config.update({
region: "'us-east-1'"
});
let GetMachineStateIntent = (context, callback, dateSlot, timeSlot) => {
var params = {
TableName: "updatedincident",
KeyConditionExpression: 'date = :dVal and time < :tVal',
ExpressionAttributeValues: {
':dVal': dateSlot,
':tVal': timeSlot
},
ScanIndexForward: false // gets values in reverse order by time
};
dbClient.query(params, function (err, data) {
if (err) {
// failed to read from table for some reason..
console.log('failed to load data item:\n' + JSON.stringify(err, null, 2));
// let skill tell the user that it couldn't find the data
sendResponse(context, callback, {
output: "the data could not be loaded from your database",
endSession: false
});
} else {
let dataItem = data.Items[0];
console.log('loaded data item:\n' + JSON.stringify(dataItem, null, 2));
// assuming the item has an attribute called "state"..
sendResponse(context, callback, {
output: dataItem.state,
endSession: false
});
}
});
};
function sendResponse(context, callback, responseOptions) {
if(typeof callback === 'undefined') {
context.succeed(buildResponse(responseOptions));
} else {
callback(null, buildResponse(responseOptions));
}
}
function buildResponse(options) {
var alexaResponse = {
version: "1.0",
response: {
outputSpeech: {
"type": "SSML",
"ssml": `<speak><prosody rate="slow">${options.output}</prosody></speak>`
},
shouldEndSession: options.endSession
}
};
if (options.repromptText) {
alexaResponse.response.reprompt = {
outputSpeech: {
"type": "SSML",
"ssml": `<speak><prosody rate="slow">${options.reprompt}</prosody></speak>`
}
};
}
return alexaResponse;
}
exports.handler = (event, context, callback) => {
try {
var request = event.request;
if (request.type === "LaunchRequest") {
sendResponse(context, callback, {
output: "welcome to my skill, I can tell you about the status of machines at different times. what data are you looking for?",
endSession: false
});
} else if (request.type === "IntentRequest") {
if (request.intent.name === "GetMachineStateIntent") {
var dateSlot = request.intent.slots.Date != null
? request.intent.slots.Date. value : null;
var timeSlot = request.intent.slots.Time != null
? request.intent.slots.Time.value : null;
// pass the slot values to the GetMachineStateIntent function
GetMachineStateIntent(context, callback, dateSlot, timeSlot);
} else if (request.intent.name === "AMAZON.StopIntent" || request.intent.name === "AMAZON.CancelIntent") {
sendResponse(context, callback, {
output: "ok. good bye!",
endSession: true
});
}
else if (request.intent.name === "AMAZON.HelpIntent") {
sendResponse(context, callback, {
output: "you can ask me about incidents that have happened or states of machines in the past",
reprompt: "what can I help you with?",
endSession: false
});
}
else {
sendResponse(context, callback, {
output: "I don't know that one! please try again!",
endSession: false
});
}
}
else if (request.type === "SessionEndedRequest") {
sendResponse(context, callback, ""); // no response needed
}
else {
// an unexpected request type received.. just say I don't know..
sendResponse(context, callback, {
output: "I don't know that one! please try again!",
endSession: false
});
}
} catch (e) {
// handle the error by logging it and sending back an failure
console.log('Unexpected error occurred in the skill handler!', e);
if(typeof callback === 'undefined') {
context.fail("Unexpected error");
} else {
callback("Unexpected error");
}
}
};
The response i currently get with my above code is
'the data could not be loaded from your database'
Cloud watch also tells me this
2018-05-16T09:29:06.635Z 93d4b6e6-58eb-11e8-b686-597d65771e90 failed to load data item:
{
"message": "Invalid KeyConditionExpression: Attribute name is a reserved keyword; reserved keyword: date",
"code": "ValidationException",
"time": "2018-05-16T09:29:06.633Z",
"requestId": "EQPQTAGO4QKH9SM5GSOA9O3DDFVV4KQNSO5AEMVJF66Q9ASUAAJG",
"statusCode": 400,
"retryable": false,
"retryDelay": 35.56027710686527
}

Answer 1

In the GetMachineStateIntent function, try changing the params structure like this:
var params = {
TableName: "updatedincident",
KeyConditionExpression: '#d = :dVal and #t < :tVal',
ExpressionAttributeValues: {
':dVal': dateSlot,
':tVal': timeSlot
},
ExpressionAttributeNames: {
'#d': 'date',
'#t': 'time'
},
ScanIndexForward: false // gets values in reverse order by time
};
It looks like the word date is a reserved keyword so it can't be used directly in an expression such as date = :dVal which is why you must give it an attribute name alias (#d) which maps back to the actual attribute name (date).

Answer 2

In DynamoDB, you have to use two keys i.e Primary key and Primary sort key. The query searches on the basis of these two keys for the requested value.
Try my code:
'FindName': function() {
var tableName = "CVRaman";
var userName = "Prateek";
var userId = "kapoor";
const dynamodbParams = {
TableName: tableName,
Key: {
userId: userId,
userName: userName,
},
ProjectionExpression: 'userName', //Projection Expression is used to select only specific columns which we want to get
};
console.log("Attempting to find name", dynamodbParams);
dynamoDb.get(dynamodbParams).promise()
.then(data => {
console.log('name found', dynamodbParams);
console.log(data.Item.userName);
var a = data.Item.userName;
console.log(a);
this.emit(':ask', 'Name as ' + a);
})
.catch(err => {
console.log(err);
this.emit(':tell', 'we have a problem');
});
},