Handling Requests

We can easily access the request’s body, params, query, and headers by including "router.h". We’ll see just basic examples in this chapter.

Let’s see how it basically works.

Request Body

src/handlers.c

#include "router.h"

void print_body(Req *req, Res *res)
{
    printf("Body: %s\n", req->body);
    reply(res, "200 OK", "text/plain", "Success");
}

src/handlers.h

#ifndef HANDLERS_H
#define HANDLERS_H

#include "router.h"

void print_body(Req *req, Res *res);

#endif

src/main.c

#include "ecewo.h"
#include "router.h"
#include "handlers.h"

int main()
{
    post("/print-body", print_body);
    ecewo(4000);
    return 0;
}

Let’s send a POST request to the http://localhost:4000/print-body with this body:

{
    "name": "John",
    "surname": "Doe",
    "username": "johndoe"
}

We’ll receive a Success message and see the body in the console:

Body: {
    "name": "John",
    "surname": "Doe",
    "username": "johndoe"
}

For more advanced usage; see the Using cJSON chapter.

Request Params

Let’s take a specific user by params. We can access the params using the get_req(&req->params, "params") API. Let’s write a handler that gives us the “slug”: But first, add routes.h the route:

src/handlers.c

#include "router.h"

void send_params(Req *req, Res *res)
{
    const char *slug = get_req(&req->params, "slug"); // We got the params

    if (slug == NULL)
    {
        reply(res, "400 Bad Request", "text/plain", "Missing 'slug' parameter");
        return;
    }

    reply(res, "200 OK", "text/plain", slug);
}

src/handlers.h

#ifndef HANDLERS_H
#define HANDLERS_H

#include "router.h"

void send_params(Req *req, Res *res);

#endif

src/main.c

#include "ecewo.h"
#include "router.h"
#include "handlers.h"

int main()
{
    get("/send-params/:slug", send_params);
    ecewo(4000);
    return 0;
}

Recompile the program and send a request to http://localhost:4000/send-params/testslug. Server will send us testslug.

We can define more than one slug if we need using the same way. Here is an example:

src/main.c

#include "ecewo.h"
#include "router.h"
#include "handlers.h"

int main()
{
    get("/print-more-params/:key/and/:value");
    ecewo(4000);
    return 0;
}

src/handlers.c

#include "router.h"

void print_more_params(Req *req, Res *res)
{
    const char *key = get_req(&req->params, "key");     // We got the /:key
    const char *value = get_req(&req->params, "value"); // We got the /:value

    if (key == NULL || value == NULL)
    {
        reply(res, "400 Bad Request", "text/plain", "Missing 'key' or 'value' parameter");
        return;
    }

    printf("Key slug: %s Value slug: %s\n", key, value);

    reply(res, "200 OK", "text/plain", "Success!");
}

src/handlers.h

#ifndef HANDLERS_H
#define HANDLERS_H

#include "router.h"

void print_more_params(Req *req, Res *res);

#endif

If we go to http://localhost:4000/print-more-params/foo/and/bar path, we’ll receive a Success! response and see the foo and bar in the console:

Key slug: foo Value slug: bar

Request Query

Like the params, we can use get_req(&req->query, "query") to get the query. Let’s rewrite a handler using query:

src/main.c

#include "ecewo.h"
#include "router.h"
#include "handlers.h"

int main()
{
    get("/print-query", print_query);
    ecewo(4000);
    return 0;
}

src/handlers.c

#include "router.h"

void print_query(Req *req, Res *res)
{
    const char *name = get_req(&req->query, "name");
    const char *surname = get_req(&req->query, "surname");

    if (name == NULL || surname == NULL)
    {
        reply(res, "400 Bad Request", "text/plain", "Missing required parameter.");
        return;
    }

    printf("Name: %s Surname: %s\n", name, surname);

    reply(res, "200 OK", "text/plain", "Success!");
}

src/handlers.h

#ifndef HANDLERS_H
#define HANDLERS_H

#include "router.h"

void print_query(Req *req, Res *res);

#endif

Let’s recompile the program and send a request to http://localhost:4000/print-query?name=john&surname=doe. We’ll receive a Success! responseand the query strings will be printed in the console:

Name: john Surname: doe

Request Headers

Just like params and query, we can also access request headers using the get_req(&req->headers, "header") API. ecewo also provides different APIs for authorization and session-based authentication. However, if you simply want to access a specific item in req->headers, you can do so directly.

Typically, a standard GET request with POSTMAN have some headers like:

{
    "User-Agent": "PostmanRuntime/7.43.3",
    "Accept": "*/*",
    "Postman-Token": "9b1c7dda-27f9-471a-9cdd-bfaf0d5b56a1",
    "Host": "localhost:3000",
    "Accept-Encoding": "gzip, deflate, br",
    "Connection": "keep-alive"
}

Let’s say, we need the User-Agent header:

src/handlers.c

#include "router.h"

void get_user_agent(Req *req, Res *res)
{
    const char *header = get_req(&req->headers, "User-Agent");

    if (header == NULL)
    {
        reply(res, "400 Bad Request", "text/plain", "Missing required parameter.");
        return;
    }

    reply(res, "200 OK", "text/plain", header);
}

src/handlers.h

#ifndef HANDLERS_H
#define HANDLERS_H

#include "router.h"

void get_user_agent(Req *req, Res *res);

#endif

src/main.c

#include "ecewo.h"
#include "router.h"
#include "handlers.h"

int main()
{
    get("/header", get_user_agent);
    ecewo(4000);
    return 0;
}

The result will be something like this:

    User Agent: PostmanRuntime/7.43.3