Fun is a simple functional web application framework for Deno
How to build web application with Fun
There are 3 steps you need to do.
Define a global context
context represents global values shared by the entire web application, like configuration, database connection. In order to build a robust web application, itās highly recommended that you initialize those resources before starting the application. It can be any data you need when you run the application.
type Context = { database: string, } const context: Context = { database: "postgresql://localhost" };
Write routes and handlers
route is build with different parser, letās say you want to build an parser match the request
GET /api/v1/users/100
(100 can be any integer), you can write code// match http method GET const get = method<Context>("GET"); const apiSegment = literal("api"); const v1Segment = literal("v1"); const usersSegment = literal("users"); // match any segment that can be parsed as an integer const userIdSegment = integer(); // match http path /api/v1/users/{any integer} const pathParser = combine([ apiSegment, v1Segment, usersSegment, userIdSegment, ] as const); // match query parameter const queryParams = query({ role: equal("admin"), }); // build an route that match GET /api/v1/users/{any integer} const paths = [get, path(pathParser), queryParams] as const; const userRoute = route<Context, typeof paths>(paths);
userRouteās type will looks like below
// Route has 2 generic parameters // 1st one is the type of Context we defined above // 2nd one is the return value of route parser, in this case // type: [string, [string, string, string, number]] // parser: [get, [api, v1, users, userId]] const userRoute: Route<Context, [string, [string, string, string, number], { role: string }]>
In order to handle the request that match the type of userRoute, you also need to provide a function which type should match with userRoute
function handler(context: Context, params: [string, [string, string, string, number], { role: string }]>): Response;
For example, you can just return context and params in handler
function handler(context: Context, params: [string, [string, string, string, number]]) { const body = { method, // GET path: [api, v1, users, userId], // ["api", "v1", "users", 100] context, }; return new Response(JSON.stringify(body), { status: 200, }); }
Create an web application and register route & handler
const app = new App<Context>(context); app.route(userRoute, handler); app.run({ port: 8080, });
Now, if you visit http://localhost:8080/api/v1/users/100, the response will be
{"method":"GET","path":["api","v1","users",100],"queryParams":{"role":"admin"},"context":{"framework":"Fun"}}
Check ./exmple.ts for a complete example.