Confused on creating an update request for DynamoDB using API Gateway - amazon-dynamodb

Question

I'm writing a lambda function to get the resources by posting the phone number. below is my code.
exports.handle = function (e, ctx, cb) {
var body = JSON.parse(e.body);
var params = {
TableName: 'userAddresses',
FilterExpression: '#phone = :phone',
ExpressionAttributeNames: {
"#phone": "phone"
},
ExpressionAttributeValues: {
":phone": body.phone
}
}
dynamodb.scan(params).promise().then(function (data) {
var uw = data.Items[0];
var res = {
"statusCode": 200,
"headers": {},
"body": JSON.stringify(uw)
};
ctx.succeed(res);
});
}
this is working fine. but I want to do the same with put and patch. Can some one please point me in a right direction.
for patch, it should be something like, the phone should be passed as a queryParameter and the body to be updated in just json body
Thanks

Answer 1

Is the phone number a hash key? If so, use dynamodb.get() or dynamodb.query() instead...
Here's a quick and dirty example, it may help you to get started with DynamoDB updates:
const AWS = require('aws-sdk);
const bluebird = require('bluebird');
AWS.config.setPromisesDependency(bluebird);
const dynamodb = new AWS.DynamoDB.DocumentClient();
let update = (id, attributes) => {
var params = {
TableName: 'MyTableName',
Key: {
myHashKeyAttr: id
},
AttributeUpdates: attributes
};
return dynamodb.update(params).promise();
};
exports.handler = (event, context, callback) => {
console.log(JSON.stringify(event, null, 2));
let body = JSON.parse(event.body);
let attributes = {
firstName: {
Action: 'PUT',
Value: body.firstName
},
lastName: {
Action: 'PUT',
Value: body.lastName
},
updatedAt: {
Action: 'PUT',
Value: new Date()
}
};
// only if the phone number is a hash key...
update(event.queryStringParameters.phone, attributes)
.then(
(result) => {
console.log(result);
callback({
statusCode: 200,
headers: {},
body: JSON.stringify({message: 'updated!'})
});
}
).catch(
(error) => {
console.error(error);
callback({
statusCode: 500,
headers: {},
body: JSON.stringify({message: 'ops!'})
});
}
);
}