AWS Lambda/API Gateway - Pass an ID to delete a row in mysql with node.js

Question

I wrote a simple restful API in Node.js for different HTTP-Requests which i then tried to realize with Lambda functions. My problem with the DELETE statement in Lambda is that i dont know how to pass an ID through the API gateway to delete a certain row in the mysql table.

With node.js, I just defined it through the route of the URL (ex. /contacts/:id) and then accessed it with .params.id. How would you pass an a value (the ID) for the same route (/contacts) to then use it in the handler below to delete a the row with that specific ID?

The Code i posted below works fine when u invoke it locally with --data, for example:

serverless invoke local --function delete --data "2"

the same code works too if i deploy the lambda if i pass the testdata { "id": "1" } and use event.id instead of event.

I realize that this is not the way you do it, but i ve finally run out of ideas and decided to post my issue here. :-) So, how do i pass and ID with my DELETE HTTP-Request to /contacts through the api gateway and use it in the mysql query?

module.exports.handler = (event, context, callback) =>
{
    const mysql = require('mysql');
    var connection = mysql.createConnection({
        host: 'localhost',
        user: 'root',
        password: ''
    });
// Use the connection
    connection.query('DELETE FROM sqllambdadb.contacts WHERE id=?', event, function (err, res) {
        if (err) throw err;
        else if (res.affectedRows>0) callback(err, 'EMail with ID: '+ event+ ' deleted!');
        else callback(err, 'No row with ID: '+ event+ ' found!');
});
        connection.end();
    };

Answer 1

API Gateway maps requests to the input event object

{
    "resource": "Resource path",
    "path": "Path parameter",
    "httpMethod": "Incoming request's method name"
    "headers": {Incoming request headers}
    "queryStringParameters": {query string parameters }
    "pathParameters":  {path parameters}
    "stageVariables": {Applicable stage variables}
    "requestContext": {Request context, including authorizer-returned key-value pairs}
    "body": "A JSON string of the request payload."
    "isBase64Encoded": "A boolean flag to indicate if the applicable request payload is Base64-encode"
}

In your example, depending on the segement's alias your using, you'd access the id by either destructuring the appropriate event object, or referencing directly via event.pathParameters.id

const mysql = require('mysql');

module.exports.handler = (event, context, callback) => {
  var connection = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: ''
  });

  //Destructing id from event.pathParameters object
  var {id} = event.pathParameters

  // Use the connection
  connection.query('DELETE FROM sqllambdadb.contacts WHERE id=?', id, function (err, res) {
    if (err) throw err;
    else if (res.affectedRows>0) callback(err, 'EMail with ID: '+ id + ' deleted!');
    else callback(err, 'No row with ID: '+ id + ' found!');
  });

  connection.end();
};

Answer 2

So, i set up the yaml to add a parameter value to my URL:

delete:
  handler: src/delete.handler
  package:
    include:
      - node_modules/**
      - src/delete.js
      - serverlessAPI.iml
  events:
    - http:
        path: contact-management/contacts/{id}
        method: delete
        cors: true
        integration: LAMBDA
        request:
          parameters:
            paths:
              id: true

with this config, the id will be saved directly in the event object under event.id so you can simply access it like this:

module.exports.handler = (event, context, callback) =>{
const mysql = require('mysql');
var connection = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: 'testt123'
});

var id = event.id;

// Use the connection
connection.query('DELETE FROM sqllambdadb.Contacts WHERE id=?', id, function (err, res) {
    if (err) throw err;
    else if (res.affectedRows>0) callback(err, 'EMail with ID: '+ id + ' deleted!');
    else callback(err, 'No row with ID: '+ id + ' found!');
});
connection.end();
};

you can test it by creating a testcase with the following input:

{
  "id": "$input.params('id')"
}