Implement functionality to support sending form data in HTTP requests. (#32)

* Implement functionality to support sending form data in HTTP requests.

* Implemented tests for POST requests.

* Update examples to use httpbin.com domain and dummyjson.com for testing purposes

* update docstring

Author: rajkumardongre

example/get.f90

@@ -5,7 +5,7 @@ program get_request
     implicit none
     type(response_type) :: response
 
-    response = request(url='https://jsonplaceholder.typicode.com/todos/1')
+    response = request(url='https://httpbin.org/get')
     if(.not. response%ok) then
         print *,'Error message : ', response%err_msg
     else

example/post.f90

@@ -7,7 +7,7 @@ program post_request
     character(:), allocatable :: json_data
     type(header_type), allocatable :: req_header(:)
 
-    req_header = [header_type('Content-Type', 'applicaiton/json')]
+    req_header = [header_type('Content-Type', 'application/json')]
 
     ! JSON data we want to send
     json_data = '{"name":"Jhon","role":"developer"}'

example/post_form_data.f90

@@ -0,0 +1,23 @@
+program post_form_data
+    ! This program demonstrates sending Form data using POST request and printing the
+    ! status, length of the body, method, and the body of the response.
+    use http, only: response_type, request, HTTP_POST, header_type, form_type
+    implicit none
+    type(response_type) :: response
+    type(header_type), allocatable :: req_header(:)
+    type(form_type), allocatable :: form_data(:)
+
+    form_data = [form_type('param1', 'value1'), form_type('param2', 'value2')]
+
+    response = request(url='https://httpbin.org/post', method=HTTP_POST, form=form_data)
+   
+    if(.not. response%ok) then
+        print *,'Error message : ', response%err_msg
+    else
+        print *, 'Response Code    : ', response%status_code
+        print *, 'Response Length  : ', response%content_length
+        print *, 'Response Method  : ', response%method
+        print *, 'Response Content : ', response%content
+    end if
+
+end program post_form_data

src/http.f90

@@ -4,4 +4,5 @@ module http
     use http_response, only: response_type
     use http_client, only: request
     use http_header, only : header_type
+    use http_form, only : form_type
 end module http

src/http/http_client.f90

@@ -0,0 +1,15 @@
+module http_form
+    !! This module contains the definition of a form_type derived type, which represents a 
+    !!single field of an HTTP form.
+    implicit none
+    private
+    public :: form_type
+
+    type :: form_type
+    !! A derived type representing a single field of an HTTP form.
+        character(:), allocatable :: name
+        !! The name of the form field 
+        character(:), allocatable :: value
+        !! The value of the form filed
+    end type form_type
+end module http_form

src/http/http_form.f90

@@ -1,4 +1,9 @@
 module http_request
+
+    !! This module contains the definition of a request_type derived type, which 
+    !! represents an HTTP request.
+
+    use http_form , only: form_type
     use http_header, only: header_type
     use stdlib_string_type, only: string_type, to_lower, operator(==), char
 
@@ -18,8 +23,18 @@ module http_request
 
     ! Request Type
     type :: request_type
-        character(len=:), allocatable :: url, data
+    !! Representing an HTTP request.
+        character(len=:), allocatable :: url
+            !! The URL of the request
+        character(len=:), allocatable :: data
+            !! The data to be send with request
+        character(len=:), allocatable :: form_encoded_str
+            !! The URL-encoded form data.
         integer :: method
+            !! The HTTP method of the request.
         type(header_type), allocatable :: header(:)
+            !! An Array of request headers.
+        type(form_type), allocatable :: form(:)
+            !! An array of fields in an HTTP form.
     end type request_type
 end module http_request

src/http/http_request.f90

@@ -1,4 +1,8 @@
 module http_response
+
+    !! This module contains the definition of a response_type derived type, which 
+    !! represents an HTTP response.
+
     use, intrinsic :: iso_fortran_env, only: int64
     use http_header, only: header_type, get_header_value
     use stdlib_string_type, only: string_type, to_lower, operator(==), char
@@ -10,22 +14,38 @@ module http_response
 
     ! Response Type
     type :: response_type
-        character(len=:), allocatable :: url, content, method, err_msg
+    !! Representing an HTTP response.
+        character(len=:), allocatable :: url
+            !! The URL of the request
+        character(len=:), allocatable :: content
+            !! The content of the response.
+        character(len=:), allocatable :: method
+            !! The HTTP method of the request.
+        character(len=:), allocatable :: err_msg
+            !! The Error message if the response was not successful.
         integer :: status_code = 0
+            !! The HTTP status code of the response
         integer(kind=int64) :: content_length = 0
+            !! length of the response content.
         logical :: ok = .true.
+            !! true if the response was successful else false.
         type(header_type), allocatable :: header(:)
+            !! An Array of response headers.
     contains
         procedure :: header_value
     end type response_type
 
 contains
-    ! The header_value function takes a key string as input and returns the corresponding 
-    ! value as a string from a response_type object's header array.
     pure function header_value(this, key) result(val)
+        !! The header_value function takes a key string as input and returns 
+        !! the corresponding value as a string from a response_type object's 
+        !! header array.
         class(response_type), intent(in) :: this
+            !! An object representing the HTTP response.
         character(*), intent(in) :: key
+            !! The key of the header value to be retrieved.
         character(:), allocatable :: val
+            !! The value of the specified key in the HTTP response header.
 
         val = get_header_value(this%header, key)
     end function header_value

src/http/http_response.f90

@@ -5,19 +5,16 @@ program test_get
     implicit none
     type(response_type) :: res
     character(:), allocatable :: msg, original_content
-    character(2), allocatable :: number
     logical :: ok = .true.
     type(header_type), allocatable :: request_header(:)
-    integer :: i, passed_test_case, fail_test_case
+    integer :: i
 
-    passed_test_case = 0
-    fail_test_case = 0
-
-    original_content = '{"data":{"id":1,"email":"george.bluth@reqres.in",&
-    &"first_name":"George","last_name":"Bluth",&
-    &"avatar":"https://reqres.in/img/faces/1-image.jpg"},&
-    &"support":{"url":"https://reqres.in/#support-heading",&
-    &"text":"To keep ReqRes free, contributions towards server costs are appreciated!"}}'
+    original_content = '{"id":1,"title":"iPhone 9","description":"An apple mobile which is nothing like &
+    apple","price":549,"discountPercentage":12.96,"rating":4.69,"stock":94,"brand":"Apple","category":&
+    "smartphones","thumbnail":"https://i.dummyjson.com/data/products/1/thumbnail.jpg","images":&
+    ["https://i.dummyjson.com/data/products/1/1.jpg","https://i.dummyjson.com/data/products/1/2.jpg",&
+    "https://i.dummyjson.com/data/products/1/3.jpg","https://i.dummyjson.com/data/products/1/4.jpg",&
+    "https://i.dummyjson.com/data/products/1/thumbnail.jpg"]}'
 
     ! setting request header
     request_header = [ &
@@ -27,7 +24,8 @@ program test_get
       header_type('User-Agent', 'my user agent') &
       ]
 
-    res = request(url='https://reqres.in/api/users/1', header=request_header)
+    ! res = request(url='https://reqres.in/api/users/1', header=request_header)
+    res = request(url='https://dummyjson.com/products/1', header=request_header)
 
     msg = 'test_get: '
 
@@ -42,51 +40,36 @@ program test_get
     if (res%status_code /= 200) then
         ok = .false.
         print '(a)', 'Failed : Status Code Validation'
-        fail_test_case = fail_test_case + 1
-    else
-        passed_test_case = passed_test_case + 1
     end if
 
     ! Content Length Validation
     if (res%content_length /= len(original_content) .or. &
         len(res%content) /= len(original_content)) then
         ok = .false.
         print '(a)', 'Failed : Content Length Validation'
-        fail_test_case = fail_test_case + 1
-    else 
-        passed_test_case = passed_test_case + 1
     end if
 
     ! Content Validation
     if (res%content /= original_content) then
         ok = .false.
         print '(a)', 'Failed : Content Validation'
-        fail_test_case = fail_test_case + 1
-    else 
-        passed_test_case = passed_test_case + 1
     end if
 
     ! Header Size Validation
-    if (size(res%header) /= 14 .and. size(res%header) /= 15) then
+    if (size(res%header) /= 16) then
         ok = .false.
         print '(a)', 'Failed : Header Size Validation'
-        fail_test_case = fail_test_case + 1
-    else 
-        passed_test_case = passed_test_case + 1
     end if
 
     ! Header Value Validation
     if (res%header_value('content-type') /= 'application/json; charset=utf-8') then
         ok = .false.
         print '(a)', 'Failed : Header Value Validation'
-        fail_test_case = fail_test_case + 1
-    else 
-        passed_test_case = passed_test_case + 1
     end if
 
     if (.not. ok) then 
-        write(stderr, '(a i2 a i2 a)'), msg, fail_test_case,'/',fail_test_case+passed_test_case,&
-        & ' Test Case Failed'
+        msg = msg // 'Test Case Failed'
+        write(stderr, '(a)'), msg
         error stop 1
     else
         msg = msg // 'All tests passed.'

test/test_get.f90

@@ -0,0 +1,54 @@
+program test_post
+    use iso_fortran_env, only: stderr => error_unit
+    use http, only: request, header_type, HTTP_POST, response_type
+    implicit none
+    type(response_type) :: res
+    character(:), allocatable :: json_data, original_content, msg
+    type(header_type), allocatable :: req_header(:)
+    logical :: ok = .true.
+
+    original_content = '{"id":101,"title":"BMW","description":"A luxurious and high-performance vehicle"}'
+    req_header = [header_type('Content-Type', 'application/json')]
+
+    json_data = '{"title":"BMW","description":"A luxurious and high-performance vehicle"}'
+
+    res = request(url='https://dummyjson.com/products/add', method=HTTP_POST, data=json_data, header=req_header)
+    
+    msg = 'test_post: '
+
+    if (.not. res%ok) then
+        ok = .false.
+        msg = msg // res%err_msg
+        write(stderr, '(a)') msg
+        error stop 1
+    end if
+
+    ! Status Code Validation
+    if (res%status_code /= 200) then
+        ok = .false.
+        print '(a)', 'Failed : Status Code Validation'
+    end if
+
+    ! Content Length Validation
+    if (res%content_length /= len(original_content) .or. &
+        len(res%content) /= len(original_content)) then
+        ok = .false.
+        print '(a)', 'Failed : Content Length Validation'
+    end if
+
+    ! Content Validation
+    if (res%content /= original_content) then
+        ok = .false.
+        print '(a)', 'Failed : Content Validation'
+    end if
+
+    if (.not. ok) then 
+        msg = msg // 'Test Case Failed'
+        write(stderr, '(a)'), msg
+        error stop 1
+    else
+        msg = msg // 'All tests passed.'
+        print '(a)', msg 
+    end if
+
+end program test_post