Development

Appwrite Functions offer a familiar interface if you've developed REST endpoints. Each function is handled following a request and response pattern.

There is a clear lifecycle for all Appwrite Functions, from beginning to end. Here's everything that happens during a function execution.

1. The function is invoked.

2. Appwrite passes in request information like headers, body or path through the context.req object.

3. The runtime executes the code you defined, you can log through the context.log() or context.error() methods.

4. Function terminates when you return results using return context.res.send(), return context.res.json() or similar.

You'll find all of these steps in a simple function like this.

import { Client } from 'node-appwrite';

// This is your Appwrite function
// It's executed each time we get a request
export default async ({ req, res, log, error }) => {
  // Why not try the Appwrite SDK?
  //
  // const client = new Client()
  //    .setEndpoint('https://cloud.appwrite.io/v1')
  //    .setProject(process.env.APPWRITE_FUNCTION_PROJECT_ID)
  //    .setKey(process.env.APPWRITE_API_KEY);

  // You can log messages to the console
  log('Hello, Logs!');

  // If something goes wrong, log an error
  error('Hello, Errors!');

  // The `req` object contains the request data
  if (req.method === 'GET') {
    // Send a response with the res object helpers
    // `res.send()` dispatches a string back to the client
    return res.send('Hello, World!');
  }

  // `res.json()` is a handy helper for sending JSON
  return res.json({
    motto: 'Build Fast. Scale Big. All in One Place.',
    learn: 'https://appwrite.io/docs',
    connect: 'https://appwrite.io/discord',
    getInspired: 'https://builtwith.appwrite.io',
  });
};

If you prefer to learn through more examples like this, explore the examples page.

Context is an object passed into every function to handle communication to both the end users, and logging to the Appwrite Console. All input, output, and logging must be handled through the context object passed in.

You'll find these properties in the context object.

Some languages, namely JavaScript, support destructuring. You'll see us use destructuring in examples, which has the following syntax.

Learn more about destructuring assignment.

// before destructuring
export default async function (context) {
    context.log("This is a log!");
    return context.res.send("This is a response!");
}

// after destructuring
export default async function ({ req, res, log, error }) {
    log("This is a log!");
    return res.send("This is a response!");
}

If you pass data into an Appwrite Function, it'll be found in the request object. This includes all invocation inputs from Appwrite SDKs, HTTP calls, Appwrite events, or browsers visiting the configured domain. Explore the request object with the following function, which logs all request params to the Appwrite Console.

export default async ({ req, res, log }) => {
    log(req.bodyRaw);                     // Raw request body, contains request data
    log(JSON.stringify(req.body));        // Object from parsed JSON request body, otherwise string
    log(JSON.stringify(req.headers));     // String key-value pairs of all request headers, keys are lowercase
    log(req.scheme);                      // Value of the x-forwarded-proto header, usually http or https
    log(req.method);                      // Request method, such as GET, POST, PUT, DELETE, PATCH, etc.
    log(req.url);                         // Full URL, for example: http://awesome.appwrite.io:8000/v1/hooks?limit=12&offset=50
    log(req.host);                        // Hostname from the host header, such as awesome.appwrite.io
    log(req.port);                        // Port from the host header, for example 8000
    log(req.path);                        // Path part of URL, for example /v1/hooks
    log(req.queryString);                 // Raw query params string. For example "limit=12&offset=50"
    log(JSON.stringify(req.query));       // Parsed query params. For example, req.query.limit

    return res.send("All the request parameters are logged to the Appwrite Console.");
};

Appwrite Functions will always receive a set of headers that provide meta data about the function execution. These are provided alongside any custom headers sent to the function.

If you need to send a response to the invoker of the function, such as a user, client app, or an integration, use the response object. The response information will not be logged to the Appwrite Console. There are several possible ways to send a response, explore them in the following Appwrite Function.

export default async ({ req, res, log }) => {

    switch (req.query.type) {
        case 'empty': 
            return res.empty();
        case 'json':
            return res.json({"type": "This is a JSON response"});
        case 'redirect':
            return res.redirect("https://appwrite.io", 301);
        case 'html':
            return res.send(
                "<h1>This is an HTML response</h1>", 200, {
                    "content-type": "text/html"
                });
        default:
            return res.send("This is a text response");
    }
}

To get the different response types, set one of the following query parameters in the generated domain of your function.

To protect user privacy, the request and response objects are not logged to the Appwrite Console by default. This means, to see logs or debug function executions you need to use the log() and error() methods. These logs are only visible to developers with access to the Appwrite Console.

Here's an example of using logs and errors.

export default async ({ req, res, log, error }) => {
    log("This is a log, use for logging information to console");
    log(`This function was called with ${req.method} method`);
    error("This is an error, use for logging errors to console");

    return res.send("Check the Appwrite Console to see logs and errors!");
};

You can access these logs through the following steps.

1. In Appwrite Console, navigate to Functions.

2. Click to open a function you wish to inspect.

3. Under the Executions tab, click on an execution.

4. In the Response section, you'll be able to view logs under the Logs and Errors tabs.

If you need to pass constants or secrets to Appwrite Functions, you can use environment variables. Environmental variables can be global, or function-specific.

Function-level environment variables will only be accessible in the function they belong to. Function-level environment variables will override project-level variables when they have conflicting names.

1. In Appwrite Console, navigate to Functions.

2. Click to open a function you wish to add variables to.

3. Under the Settings tab, navigate to Environment variables.

4. Create an environment variable by clicking Create variable, using the Editor, or import new variables through a .env file.

Project-level variables are accessible to all Appwrite Functions in your project. Function-level environment variables will override project-level variables when they have conflicting names.

In the Appwrite Console, navigate to your project's Settings page. Navigate to Global variables section. Create an environment variable by clicking Create variable, using the Editor, or import new variables through a .env file.

You can access the environment variables through the systems library of each language.

export default async ({ req, res, log }) => {
    return res.send(process.env.MY_VAR);
}

Your function's dependencies should be managed by the package manager of each language. By default, we include the following package managers in each runtime.

	Language	Package Manager	Commands
	Node.js	NPM	npm install
	PHP	Composer	composer install
	Python	pip	pip install -r requirements.txt
	Ruby	Bundler	bundle install
	Deno	deno	deno cache <ENTRYPOINT_FILE>
	Dart	pub	pub get
	Swift	Swift Package Manager	swift package resolve
	.NET	NuGet	dotnet restore
	Kotlin	Gradle	N/A
	Java	Gradle	N/A
	C++	None	N/A

To install your dependencies before your function is built, you should add the relevant install command to the top your function's Build setting > Commands.

Appwrite can be used in your functions by adding the relevant SDK to your function's dependencies. Authenticating with Appwrite is done via an API key or a JWT token. API keys must be generated and exported as an environment variable.

You can read more about authentication in the JWT login section of the docs.

API keys have defined scopes when you create them. They ignore permissions and operate without a sessions. Use API keys if the function should act as an admin type role, instead of acting on behalf of a user. Pass in your API key as an environment variable. Never share API keys with users.

import { Client, Databases, ID } from 'node-appwrite';

export default async ({ req, res, log, error }) => {

    const client = new Client()
        .setEndpoint('https://cloud.appwrite.io/v1')
        .setProject(process.env.APPWRITE_FUNCTION_PROJECT_ID)
        .setKey(process.env.APPWRITE_API_KEY);

    const databases = new Databases(client);

    try {
        await databases.createDocument(
            '[DATABASE_ID]',
            '[COLLECTION_ID]',
            ID.unique(),
            {}
        )
    } catch (e) {
        error("Failed to create document: " + e.message)
        return res.send("Failed to create document")
    }

    return res.send("Document created")
}

JWTs allow you to act on behalf of an user in your Appwrite Function. When using JWTs, you will be able to access and change only the resources with the same permissions as the user account that signed the JWT. This preserves the permissions you configured on each resource.

If the Appwrite Function is invoked by an authenticated user, the x-appwrite-user-jwt header is automatically passed in.

import { Client, Databases, ID } from 'node-appwrite';

export default async ({ req, res, log }) => {
    const client = new Client()
        .setEndpoint('https://cloud.appwrite.io/v1')
        .setProject(process.env.APPWRITE_FUNCTION_PROJECT_ID)

    if (req.headers['x-appwrite-user-jwt']) {
        client.setJWT(req.headers['x-appwrite-user-jwt'])
    } else {
        return res.send("Please sign in, JWT not found")
    }

    const databases = new Databases(client);

    try {
        await databases.createDocument(
            '[DATABASE_ID]',
            '[COLLECTION_ID]',
            ID.unique(),
            {}
        )
    } catch (e) {
        log("Failed to create document: " + e.message)
        return res.send("Failed to create document")
    }

    return res.send("Document created")
}

Code splitting

As your functions grow, you may find yourself needing to split your code into multiple files. This helps you keep your codebase maintainable and easy to read. Here's how you can accomplish code splitting.

// src/utils.js
export function add(a, b) {
    return a + b;
}

// src/main.js
import { add } from './utils.js';

export default function ({ res }) {
    return res.send(add(1, 2));
}

<?php
// src/utils.php
function add($a, $b) {
    return $a + $b;
}

<?php
// src/main.php
require_once(__DIR__ . '/utils.php');

return function ($context) {
    return $context->res->send(add(1, 2));
};

# src/utils.py
def add(a, b):
    return a + b

# src/main.py
from .utils import add

def main(context):
    return context.res.send(add(1, 2))

# lib/utils.rb
def add(a, b)
    return a + b
end

# lib/main.rb
require_relative 'utils'

def main(context)
    return context.res.send(add(1, 2))
end

// src/utils.ts
export function add(a: number, b: number): number {
    return a + b;
}

// src/main.ts
import { add } from './utils.ts';

export default function ({res}: {res: any}) {
    return res.send(add(1, 2));
}

// lib/utils.dart
int add(int a, int b) {
    return a + b;
}

// lib/main.dart
import 'dart:async';

import 'package:package_name/utils.dart';

Future<dynamic> main(final context) async {
    return context.res.send(add(1, 2));
}

// Sources/utils.swift
func add(_ a: Int, _ b: Int) -> Int {
    return a + b
}

// Sources/index.swift
import Foundation

func main(context: RuntimeContext) async throws -> RuntimeOutput {
    return context.res.send(add(1, 2))
}

// src/Utils.cs
namespace DotNetRuntime
{
    public static class Utils
    {
        public static int Add(int a, int b)
        {
            return a + b;
        }
    }
}

// src/Index.cs
namespace DotNetRuntime
{
    public class Handler {
        public async Task<RuntimeOutput> Main(RuntimeContext Context)
        {
            return Context.Res.Send(Utils.Add(1, 2));
        }
    }
}

// src/Utils.kt
package io.openruntimes.kotlin.src

object Utils {
    fun add(a: Int, b: Int): Int {
        return a + b
    }
}

// src/Main.kt
package io.openruntimes.kotlin.src

import io.openruntimes.kotlin.RuntimeContext
import io.openruntimes.kotlin.RuntimeOutput
import io.openruntimes.kotlin.Utils

class Main {
    fun main(context: RuntimeContext): RuntimeOutput {
        return context.res.send(Utils.add(1, 2))
    }
}

// src/Utils.java
package io.openruntimes.java.src;

class Utils {
    public static int add(int a, int b) {
        return a + b;
    }
}

package io.openruntimes.java.src;

import io.openruntimes.java.RuntimeContext;
import io.openruntimes.java.RuntimeOutput;
import io.openruntimes.java.Utils;

public class Main {
    public RuntimeOutput main(RuntimeContext context) throws Exception {
        return context.res.send(Utils.add(1, 2));
    }
}

Upgrade

Appwrite Functions received major updates in Appwrite version 1.4. If you still have functions from previous versions, they will be read-only in Appwrite 1.4. You will have to migrate your old functions to follow new runtime syntax.

Here's a checklist of things you need to know.

1. The parameter passed into functions has changed. req and res has been replaced by context, which contains new logger methods. Learn about context.

2. To improve privacy and logging reliability, we provide new context.log() and context.error() functions. You can no longer use native logging methods. Learn about logging.

3. The old way of req.variables has been deprecated. You can now access variables passed into each function as environment variables. Learn about environment variables.

4. The req object has been updated to use terminology consistent with typical HTTP concepts. You'll now find familiar concepts like headers, body, HTTP methods, and others. Learn about request.

5. The response object has been updated. You can now specify headers, as well as use new methods like return redirects or empty responses. Learn about response.

6. Now, you must return a response such as return context.res.send(""). This prevents confusing errors when functions are terminated prematurely before a response is sent. Learn about response.

7. Some variables about how a function was triggered are now found in the context.req object as headers.