jaypie v1.1.31

Jaypie 🐦‍⬛

Event-driven fullstack architecture centered around JavaScript, AWS, and the JSON:API specification

"JavaScript on both sides and underneath"

🐦‍⬛ Introduction

Jaypie is an opinionated approach to application development centered around JavaScript and the JSON:API specification in an event-driven architecture.

Jaypie is suited for applications that require custom infrastructure beyond HTTP requests (e.g., message queues). Without custom infrastructure, fullstack hosts like Vercel or Netlify are recommended.

"Jaypie Stack"

• AWS infrastructure managed by CDK in Node.js
• Express server running on AWS Lambda
• Node.js worker processes running on AWS Lambda
• MongoDB via Mongoose
• Vue ecosystem frontend: Vue 3 composition, Vuetify, Pinia
• Vitest for testing
• ES6 syntax enforced via ESLint
• Prettier formatting
• JSON logging with custom metadata

Philosophy

Jaypie is for building fullstack JavaScript applications.

JavaScript Only 💛

Jaypie uses the AWS Cloud Development Kit (CDK) to manage infrastructure, which is written in Node.js. This makes managing infrastructure accessible to the fullstack developer without learning a new syntax and living without language constructs like loops and inheritance.

Does NOT use Kubernetes, Docker, Terraform, or the "Serverless" framework.

Eject Anything ⏏️

Jaypie embraces "ejectability," the philosophy that any part of the code can be removed (and therefore replaced) without disturbing the whole.

Mock Everywhere 🎴

Jaypie strives to be "mockable-first" meaning all components should be easily tested via default or provided mocks.

📋 Usage

Installation

Base Package

npm install jaypie

@jaypie/core is included in jaypie. Almost every Jaypie package requires core.

Peer Packages

These packages are included in jaypie. They may be installed separately in the future.

TestKit

Matchers, mocks, and utilities to test Jaypie projects.

npm install --save-dev @jaypie/testkit

Example

npm install jaypie @jaypie/lambda

const { InternalError, lambdaHandler, log } = require("jaypie");

export const handler = lambdaHandler(async({event}) => {
  // await new Promise(r => setTimeout(r, 2000));
  if (event.something === "problem") {
    throw new InternalError();
  }
  // log.debug("Hello World");
  return "Hello World";
}, { name: "example"});

This example would then be deployed to AWS via CDK or similar orchestration. See @jaypie/cdk.

📖 Reference

AWS

import { 
  getMessages,
  getSecret,
  sendBatchMessages,
  sendMessage,
} from "jaypie";

getMessages(event)

Return an array of message bodies from an SQS event.

import { getMessages } from '@jaypie/aws';

const messages = getMessages(event);
// messages = [{ salutation: "Hello, world!" }, { salutation: "Hola, dushi!" }]

getSecret(secretName: string)

Retrieve a secret from AWS Secrets Manager using the secret name.

import { getSecret } from '@jaypie/aws';

const secret = await getSecret("MongoConnectionStringN0NC3-nSg1bR1sh");
// secret = "mongodb+srv://username:password@env-project.n0nc3.mongodb.net/app?retryWrites=true&w=majority";

sendBatchMessages({ messages, queueUrl })

Batch and send messages to an SQS queue. If more than ten messages are provided, the function will batch them into groups of ten or less (per AWS).

import { sendBatchMessages } from '@jaypie/aws';

const messages = [
  { salutation: "Hello, world!" },
  { salutation: "Hola, dushi!" },
];
const queueUrl = "https://sqs.us-east-1.amazonaws.com/123456789012/MyQueue";

await sendBatchMessages({ messages, queueUrl });

sendMessage({ body, queueUrl })

Send a single message to an SQS queue.

import { sendMessage } from '@jaypie/aws';

const body = "Hello, world!";
const queueUrl = "https://sqs.us-east-1.amazonaws.com/123456789012/MyQueue";

const response = await sendMessage({ body, queueUrl });

Constants

import { 
  CDK,
  DATADOG,
  ERROR,
  EXPRESS,
  HTTP,
  VALIDATE,
} from "jaypie";

CDK

• CDK.ACCOUNT
• CDK.ENV
• CDK.ROLE
• CDK.SERVICE
• CDK.TAG

See constants.js in @jaypie/core.

DATADOG

• DATADOG.METRIC.TYPE.UNKNOWN
• DATADOG.METRIC.TYPE.COUNT
• DATADOG.METRIC.TYPE.RATE
• DATADOG.METRIC.TYPE.GAUGE

ERROR

Default messages and titles for Jaypie errors.

• ERROR.MESSAGE
• ERROR.TITLE

See HTTP for status codes.

EXPRESS

• EXPRESS.PATH.ANY - String * for any path
• EXPRESS.PATH.ID - String /:id for an ID path
• EXPRESS.PATH.ROOT - Regular expression for root path

HTTP

• HTTP.ALLOW.ANY
• HTTP.CODE: OK, CREATED, ...
• HTTP.CONTENT.ANY
• HTTP.CONTENT.HTML
• HTTP.CONTENT.JSON
• HTTP.CONTENT.TEXT
• HTTP.HEADER: ...
• HTTP.METHOD: GET, POST, ...

VALIDATE

• VALIDATE.ANY - Default
• VALIDATE.ARRAY
• VALIDATE.CLASS
• VALIDATE.FUNCTION
• VALIDATE.NUMBER
• VALIDATE.NULL
• VALIDATE.OBJECT
• VALIDATE.STRING
• VALIDATE.UNDEFINED

Internal Constants

• JAYPIE - for consistency across Jaypie
• PROJECT - for consistency across projects

Datadog

const { 
  submitMetric, 
  submitMetricSet 
} = require("jaypie");

submitMetric({ name, tags, type, value })

import { submitMetric } from "jaypie";

await submitMetric({
  name: "jaypie.metric",
  type: DATADOG.METRIC.TYPE.COUNT,
  value: 1,
});

submitMetricSet({ tags, type, valueSet })

import { submitMetricSet } from "jaypie";

await submitMetricSet({
  type: DATADOG.METRIC.TYPE.GAUGE,
  valueSet: {
    "jaypie.metric.a": 1,
    "jaypie.metric.b": 2,
    "jaypie.metric.c": 3,
  },
});

Errors

Throwing/Catching Errors

// See `Error Reference` for full list
const { InternalError } = require("jaypie");

try {
  // Code happens...
  throw InternalError("Oh, I am slain!");
} catch (error) {
  // Is this from a jaypie project?
  if(error.isProjectError) {
    {
      name,   // ProjectError
      title,  // "Internal Server Error"
      detail, // "Oh, I am slain"
      status, // 500 (HTTP code)
    } = error;
  } else {
    // Not from jaypie
    throw error;
  }
}

Format Error

if(error.isProjectError) {
  return error.json();
}

Multi-Error Usage

const errors = [];
errors.push(BadGatewayError());
errors.push(NotFoundError());
throw MultiError(errors);

Error Reference

Special Errors

ALWAYS internal to the app, NEVER something the client did

• Configuration
  • "The person writing the code did something wrong" like forgot to pass or passed bad arguments
  • "The person who configured the application made a mistake" like set mutually exclusive settings to true
• Illogical
  • A combination of truth conditions occurred that should not be able to occur at the same time
• Not Implemented
  • A marker to come back and finish this, but allows stubbing out HTTP endpoints
• Unhandled
  • Internal to Jaypie, should not be thrown directly
  • Jaypie expects code in handlers to handler errors and re-throw a Jaypie error
  • If an unexpected error escapes the handler, Jaypie returns this when it is caught
• Unreachable
  • In theory the block is literally not reachable and we want to put something there to make sure it stays that way
  • For example, a complicated chain of if/else that should always return and cover all cases, may throw this as the last else
  • A configuration error means what happened was possible but should not have happened, an unreachable error means it should not have been possible

Express

The Express handler wraps the Jaypie handler for Express running on AWS Lambda. It will call lifecycle methods and provide logging. Unhandled errors will be thrown as UnhandledError. It adds the locals lifecycle call. It extends jaypieHandler, not the lambda handler.

const { expressHandler } = require("jaypie");

const handler = expressHandler(async(req, res) => {
  // await new Promise(r => setTimeout(r, 2000));
  // log.debug("Hello World");
  return { message: "Hello World" };
}, { name: "lambdaReference"});

The order of options and handler may be swapped to improve readability. Having lifecycle methods listed before the handler may read more intuitively.

const handler = expressHandler({ 
  name: "expressOptions",
  setup: [connect],
  teardown: [disconnect],
}, async(req, res) => {
  // await new Promise(r => setTimeout(r, 2000));
  // log.debug("Hello World");
  return { message: "Hello World" };
});

Return Types

Do not use res.send or res.json in the handler. The return value of the handler is the response body. The status code is determined by the error thrown or the return value. Custom status codes can be set by calling res.status in the handler.

Errors can be returned by throwing the appropriate Jaypie error.

Lifecycle Methods

In addition to the Jaypie lifecycle methods, expressHandler adds locals, an object of scalars or functions that will be called at the end of setup and available to the handler as req.locals.

const handler = expressHandler(async(req) => {
  // req.locals.asyncFn = "async"
  // req.locals.fn = "function"
  // req.locals.key = "static"
  return { message: "Hello World" };
}, { 
  name: "expressReference",
  locals: { 
    asyncFn: async() => "async",
    fn: () => "function",
    key: "static"
  },
});

Convenience Routes

A "handler" returns a function that can be used as an Express route. A "route" does not require instantiation.

import { 
  echoRoute,
  EXPRESS,
  forbiddenRoute,
  goneRoute,
  noContentRoute,
  notFoundRoute,
  notImplementedRoute,
} from "jaypie";

app.get(EXPRESS.PATH.ROOT, noContentRoute); // 204 No Content
app.get(EXPRESS.PATH.ANY, echoRoute); // 200 OK returning the request
app.post(EXPRESS.PATH.ANY, forbiddenRoute); // 403 Forbidden
app.any("/future", notImplementedRoute); // 400 Bad Request

notImplementedRoute returns "400 Bad Request" as a placeholder for future functionality. In this regard, calling it is a "user error." The "501 Not Implemented" status code is reserved for the server not supporting parts of the HTTP protocol such as POST or PUT.

Functions

cloneDeep

lodash.clonedeep from NPM

import { cloneDeep } from "jaypie";

const original = { a: 1, b: { c: 2 }};
const clone = cloneDeep(original);

envBoolean

Look up a key in process.env and coerce it into a boolean. Returns true for true (case-insensitive) and 1 for string, boolean, and numeric types. Returns false for false (case-insensitive) and 0 for string, boolean, and numeric types. Returns undefined otherwise.

const { envBoolean } = require("jaypie");

process.env.AWESOME = true;

if (envBoolean("AWESOME")) {
  console.log("Awesome!");
}

envBoolean: defaultValue

const { envBoolean } = require("jaypie");

if (envBoolean("AWESOME", { defaultValue: true })) {
  console.log("Awesome!");
}

envsKey

envsKey(key:string, { env:string = process.env.PROJECT_ENV || process.env.DEFAULT_ENV })

return process.env.${KEY} || ENV_${ENV}_${KEY} || false

DEFAULT_ENV=sandbox

MONGODB_URI=...
ENV_SANDBOX_MONGODB_URI=...
ENV_DEVELOPMENT_MONGODB_URI=...

PROJECT_ENV=development

Return order: 1. MONGODB_URI - the exact key always takes precedence, if set 2. ENV_DEVELOPMENT_MONGODB_URI - the PROJECT_ENV, if set. Usually this is set in the deploy workflow 3. ENV_SANDBOX_MONGODB_URI - the DEFAULT_ENV, if set. Usually this is set in the local environment 4. false

import { envsKey } from "jaypie";

const url = envsKey("MONGODB_URI");

force

Coerce a value into a type or throw an error. Forcing arrays is the primary use case.

import { force } from "jaypie";

argument = force(thing, Array);
argument = force([thing], Array);
// argument = [thing]

force supports Array, Boolean, Number, Object, and String.

argument = force(argument, Array);
argument = force(argument, Boolean, "true");
argument = force(argument, Number, "12");
argument = force(argument, Object, "key");
argument = force(argument, String, "default");

// Convenience functions
argument = force.array(argument);
argument = force.boolean(argument);
argument = force.number(argument);
argument = force.object(argument, "key");
argument = force.string(argument);

getHeaderFrom

getHeaderFrom(headerKey:string, searchObject:object)

Case-insensitive search inside searchObject for headerKey. Also looks in header and headers child object of searchObject, if headerKey not found at top-level.

getObjectKeyCaseInsensitive(object:object, key:string)

Case-insensitive search for key in object. Returns the value of the key or undefined.

placeholders

Lightweight string interpolation

import { placeholders } from "jaypie";

const string = placeholders("Hello, {name}!", { name: "World" });
// string = "Hello, World!"

The code for placeholders was written by Chris Ferdinandi and distributed under the MIT License in 2018-2019. Their web site is https://gomakethings.com

safeParseFloat

parseFloat that returns 0 for NaN

sleep

sleep is a promise-based setTimeout that resolves after a specified number of milliseconds. It will NOT run when NODE_ENV is test. See sleepAlways for a version that will run in tests.

import { sleep } from "jaypie";

await sleep(2000);

This is "bad code" because it checks NODE_ENV during runtime. The "right way" is to let sleep run and mock it in tests, in practice this is needless boilerplate. A fair compromise would be to mock sleep with @jaypie/testkit but not all projects include that dependency. Jaypie will trade academically incorrect for human convenience and simplicity.

uuid

The v4 function from the uuid package

import { uuid } from "jaypie";

const id = uuid();

validate

import { validate, VALIDATE } from "jaypie";

validate(argument, {
  type: VALIDATE.ANY,
  falsy: false,     // When `true`, allows "falsy" values that match the type (e.g., `0`, `""`)
  required: true,   // When `false`, allows `undefined` as a valid value
  throws: true      // When `false`, returns `false` instead of throwing error
});

Validate Convenience Functions

import { validate } from "jaypie";

validate.array(argument);
validate.class(argument);
validate.function(argument);
validate.null(argument);
validate.number(argument);
validate.object(argument);
validate.string(argument);
validate.undefined(argument);

Intuitive Validate Types

Does not include any, class, or undefined

validate(argument, {
  // One of:
  type: Array,
  type: Function,
  type: Number,
  type: null,
  type: Object,
  type: String,
})

Jaypie Handler

The Jaypie handler can be used directly but is more likely to be wrapped in a more specific handler. The Jaypie handler will call lifecycle methods and provide logging. Unhandled errors will be thrown as UnhandledError.

import { jaypieHandler } from "jaypie";

const handler = jaypieHandler(async(...args) => {
  // await new Promise(r => setTimeout(r, 2000));
  // log.var({ args });
  return "Hello World";
}, { name: "jaypieReference"});

Jaypie Lifecycle Methods

Each function receives the same arguments as the handler.

validate: [async Function]

Returns true to validate the request. Throw an error or return false to reject the request.

setup: [async Function]

Called before the handler (e.g., connect to a database). Throw an error to halt execution.

handler: async Function

The main function to handle the request. Throw an error to halt execution.

teardown: [async Function]

Called after the handler (e.g., disconnect from a database). Runs even if setup or handler throws errors.

Lambda Handler

The Lambda handler wraps the Jaypie handler for AWS Lambda. It will call lifecycle methods and provide logging. Unhandled errors will be thrown as UnhandledError.

const { lambdaHandler } = require("jaypie");

const handler = lambdaHandler(async({event}) => {
  // await new Promise(r => setTimeout(r, 2000));
  // log.debug("Hello World");
  return "Hello World";
}, { name: "lambdaReference"});

Logging

import { 
  log,
} from "jaypie";

log

import { log } from "jaypie";

log.trace();
log.debug();
log.info();
log.warn();
log.error();
log.fatal();

log.lib({ lib: "myLib" })

Uses silent by default. if process.env.MODULE_LOG_LEVEL is true, follows process.env.LOG_LEVEL. If process.env.MODULE_LOG_LEVEL is also set, uses that log level.

import { log } from "jaypie";

log.lib().trace();
log.lib({ lib: "myLib" }).trace();

log.tag(key, value) or log.tag({ key: value })

Permanently add the key-value pair to the logger's tags, or at least until log.untag(key) is called.

import { log } from "jaypie";

log.tag("myTag", "myValue");
log.tag({ myTag: "myValue" });

log.untag(key) or log.untag(key1, key2, ...)

Remove the key-value pair from the logger's tags.

import { log } from "jaypie";

log.untag("myTag");
log.untag(["myTag1", "myTag2"]);

log.var(key, value) or log.var({ key: value })

Log a key-value pair. In the json format, the key will be tagged as var and the value will be the value. Logging marker variables this way can be useful for debugging.

import { log } from "jaypie";

log.var("message", "Hello, world");
log.var({ message: "Hello, world" });

const message = "Hello, world";
log.var({ message });

log.with() - clone

Create a new log object with additional tags

import { log as defaultLogger } from "jaypie";

const log = defaultLogger.with({ customProperty: "customValue" });

Mongoose

import { 
  connect,
  connectFromSecretEnv, 
  disconnect, 
  mongoose,
} from "jaypie";

connect

Jaypie lifecycle method to connect to MongoDB. Uses process.env.SECRET_MONGODB_URI AWS Secret or process.env.MONGODB_URI string to connect.

import { connect, disconnect, lambdaHandler, mongoose } from "jaypie";

const handler = lambdaHandler(async({event}) => {
  // mongoose is already connected
  return "Hello World";
}, { 
  name: "lambdaReference"
  setup: [connect],
  teardown: [disconnect],
});

connectFromSecretEnv

Jaypie lifecycle method to connect to MongoDB using process.env.MONGO_CONNECTION_STRING. Using the newer connect is generally preferred.

import { connectFromSecretEnv, disconnect, lambdaHandler, mongoose } from "jaypie";

const handler = lambdaHandler(async({event}) => {
  // mongoose is already connected
  return "Hello World";
}, { 
  name: "lambdaReference"
  setup: [connectFromSecretEnv],
  teardown: [disconnect],
});

disconnect

Jaypie lifecycle method to disconnect from MongoDB.

import { disconnect, lambdaHandler } from "jaypie";

const handler = lambdaHandler(async({event}) => {
  // ...
}, {
  teardown: [disconnect],
});

mongoose

mongoose from NPM

import { mongoose } from "jaypie";

TestKit

npm install --save-dev @jaypie/testkit

Log Spying

import { restoreLog, spyLog } from "@jaypie/testkit";
import { log } from "@jaypie/core";

beforeEach(() => {
  spyLog(log);
});
afterEach(() => {
  restoreLog(log);
  vi.clearAllMocks();
});

test("log", () => {
  log.warn("Danger");
  expect(log.warn).toHaveBeenCalled();
  expect(log.error).not.toHaveBeenCalled();
});

👺 Logging Conventions:

• Only use log.trace or log.var during "happy path"
• Use log.debug for edge cases
• Now you can add an "observability" test that will fail as soon as new code triggers an unexpected edge condition

describe("Observability", () => {
  it("Does not log above trace", async () => {
    // Arrange
    // TODO: "happy path" setup
    // Act
    await myNewFunction(); // TODO: add any "happy path" parameters
    // Assert
    expect(log.debug).not.toHaveBeenCalled();
    expect(log.info).not.toHaveBeenCalled();
    expect(log.warn).not.toHaveBeenCalled();
    expect(log.error).not.toHaveBeenCalled();
    expect(log.fatal).not.toHaveBeenCalled();
  });
});

👺 Follow the "arrange, act, assert" pattern

Test Matchers

testSetup.js

import { matchers as jaypieMatchers } from "@jaypie/testkit";
import * as extendedMatchers from "jest-extended";
import { expect } from "vitest";

expect.extend(extendedMatchers);
expect.extend(jaypieMatchers);

test.spec.js

import { ConfigurationError } from "@jaypie/core";

const error = new ConfigurationError();
const json = error.json();
expect(error).toBeJaypieError();
expect(json).toBeJaypieError();

expect(subject).toBeJaypieError()

Validates instance objects:

try {
  throw new Error("Sorpresa!");
} catch (error) {
  expect(error).not.toBeJaypieError();
}

Validates plain old JSON:

expect({ errors: [ { status, title, detail } ] }).toBeJaypieError();

Jaypie errors, which are ProjectErrors, all have a .json() to convert

expect(subject).toBeValidSchema()

import { jsonApiErrorSchema, jsonApiSchema } from "@jaypie/testkit";

expect(jsonApiErrorSchema).toBeValidSchema();
expect(jsonApiSchema).toBeValidSchema();
expect({ project: "mayhem" }).not.toBeValidSchema();

From jest-json-schema toBeValidSchema.js (not documented in README)

expect(subject).toMatchSchema(schema)

import { jsonApiErrorSchema, jsonApiSchema } from "@jaypie/testkit";
import { ConfigurationError } from "@jaypie/core";

const error = new ConfigurationError();
const json = error.json();
expect(json).toMatchSchema(jsonApiErrorSchema);
expect(json).not.toMatchSchema(jsonApiSchema);

From jest-json-schema; see README

TestKit Sundry

import { 
  jsonApiErrorSchema,
  jsonApiSchema,
  mockLogFactory,
} from '@jaypie/testkit'

jsonApiErrorSchema

A JSON Schema validator for the JSON:API error schema. Powers the toBeJaypieError matcher (via toMatchSchema).

jsonApiSchema

A JSON Schema validator for the JSON:API data schema.

mockLogFactory()

Creates a mock of the log provided by @jaypie/core.

import { mockLogFactory } from "@jaypie/testkit";

const log = mockLogFactory();
log.warn("Danger");
expect(log.warn).toHaveBeenCalled();
expect(log.error).not.toHaveBeenCalled();

restoreLog(log)

Restores the log provided by @jaypie/core, commonly performed afterEach with spyLog in beforeEach. See example with spyLog.

spyLog(log)

Spies on the log provided by @jaypie/core, commonly performed beforeEach with restoreLog in afterEach.

import { restoreLog, spyLog } from "@jaypie/testkit";
import { log } from "@jaypie/core";

beforeEach(() => {
  spyLog(log);
});
afterEach(() => {
  restoreLog(log);
  vi.clearAllMocks();
});

test("log", () => {
  log.warn("Danger");
  expect(log.warn).toHaveBeenCalled();
  expect(log.error).not.toHaveBeenCalled();
});

🌠 Wishlist

• Optional loading of Jaypie side packages
• ...Nicely organized VitePress documentation 😅

📝 Changelog

📜 License

Published by Finlayson Studio. All rights reserved