REST, RESTful API Quick Reference

Daniel Opitz
Daniel Opitz
17 Apr 2017

A good API is not just easy to use but also hard to misuse.

Ressources

Security

Authentication

HTTP Header

HTTP Methods

HTTP Method HTTP Path CRUDL SQL OperationId Description Response codes
GET /users List SELECT listUsers / getUsers Used for retrieving a list of resources 200 (OK), 404 (Not Found)
GET /users/{id} Read SELECT getUserById Used for retrieving a single resources 200 (OK), 404 (Not Found)
POST /users Create INSERT createUser or addUser Used for creating resources 201 (Created), 404 (Not Found), 409 (Conflict)
PUT /users/{id} Update UPDATE updateUser Used for updating resources 200 (OK), 204 (No Content), 404 (Not Found)
DELETE /users/{id} Delete DELETE deleteUser Used for deleting resources 200 (OK), 404 (Not Found)

HTTP Status Codes

Status codes indicate the result of the HTTP request.

Return meaningful status codes:

Code Name What does it mean?
200 OK All right!
201 Created If resource was created successfully.
400 Bad Request 4xx Client Error
401 Unauthorized You are not logged in, e.g. using a valid access token
403 Forbidden You are authenticated but do not have access to what you are trying to do
404 Not found The resource you are requesting does not exist
405 Method not allowed The request type is not allowed, e.g. /users is a resource and POST /users is a valid action but PUT /users is not.
409 Conflict If resource already exists.
422 Unprocessable entity Validation failed. The request and the format is valid, however the request was unable to process. For instance when sent data does not pass validation tests.
500 Server error 5xx Server Error. An error occured on the server which was not the consumer’s fault.

Error handling

General server error

Send a 500 Internal Server Error response.

HTTP Statuscode: 500

Content:

{
  "error": {
    "message": "Application Error"
  }
}

Content with error code:

{
  "error": {
    "code": 5001,
    "message": "Database connection failed"
  }
}

General client error

Sending invalid JSON will result in a 400 Bad Request response.

HTTP Statuscode: 400

Content:

{
  "error": {
    "code": 400,
    "message": "Problems parsing JSON"
  }
}

Validation errors

Sending invalid fields will result in a 422 Unprocessable Entity response.

HTTP Statuscode: 422

Content:

{
  "error": {
    "code": 422,
    "message": "Validation failed",
    "errors": [
      {
        "field": "email",
        "message": "Email is required"
      }
    ]
  }
}

Sample calls

jQuery

// Get base url
var url = $('head base').attr('href')

A GET request:

$.ajax({
    url: url + "users/1",
    type: "GET",
    cache: false,
    contentType: 'application/json',
    dataType: 'json'
}).done(function (data) {
    alert('Successfully');
    console.log(data);
}).fail(function (xhr) {
    var message = 'Server error';
    if (xhr.responseJSON && xhr.responseJSON.error.message) {
       message = xhr.responseJSON.error.message;
    }
    alert(message);
});

A POST request with payload:

var data = {
    username: "max",
    email: "max@example.com"
};

$.ajax({
    url: url + "users",
    type: "POST",
    contentType: 'application/json',
    dataType: 'json',
    data: JSON.stringify(data)
}).done(function (data) {
    alert("Success");
    console.log(data);
}).fail(function (xhr) {
    if (xhr.status === 422) {
        // Show validation errors
        var response = xhr.responseJSON;
        alert(response.error.message);
        $(response.error.errors).each(function (i, error) {
           console.log("Error in field [" + error.field + "]: " + error.message);
        });
    } else {
        var message = 'Server error';
        if (xhr.responseJSON && xhr.responseJSON.error.message) {
           message = xhr.responseJSON.error.message;
        }
        alert(message);
    }
});

Controllers