How to post on Facebook with API from a Delphi application

Step-by-step guide with screenshots and code sample

Posted by: Alex A. Publish date: 16.01.2022

Facebook is the world’s most popular social platform used by businesses to communicate with their clients, and not only.

The daily amount of information (texts, videos, images, urls) being posted in Facebook business accounts is huge and keeps growing. That’s why big companies often apply software solutions to distribute content effectively and in time.

In this article we’ll show you how to automate the process of content posting and updating through Facebook API (namely Facebook Graph API).

We’ll develop a Delphi FMX software application to post on a user’s Facebook page. 

The whole process can be split into the following steps:

  • create a Facebook app
  • make the required adjustments in the app
  • debug and test queries using the built-in Facebook API debugging tool called Graph API Explorer
  • develop a Delphi Fmx (cross-platform) software application
  • post some content on a Facebook page

To work with Facebook Graph API we’ll use GET, POST and DELETE methods and requests. The server response will be in JSON format. 

Creating a Facebook application (not a Delphi app)

To work with Facebook Graph API you first need to sign in with your Facebook account (sign up if you do not have one). Then you need to go https://developers.facebook.com and register as a developer.

sign in with your Facebook account

Then you need to confirm your email address

create a facebook for developers account

Select the profile type and click “Complete registration”.

create a facebook app in My Apps

To start using the Facebook API you need to create a facebook app in My Apps.

create a facebook app in My Apps

Select “Company” application type.

Company application type on Facebook
ALT text : Company application type on Facebook Filename: Company application type on Facebook 2

Next, enter the application name, select its purpose and click Create App.

register facebook application name

Next enter your Facebook login password

enter your Facebook login password

Congrats! You’ve just created a Facebook app. 

Now we need to get a token to access the page and configure the appropriate permissions to start posting.

get a Facebook token access to a page

To get the token run Graph API Explorer.

run Facebook Graph API Explorer

The Graph API Explorer will help us get the access token so that we can execute test queries and post to the page ( Softacom’s test page).

get the access token with Facebook Graph API Explorer

To work with the Facebook app select it from the drop-down list. To get the token to access the page, choose Get Page Access Token from the User or Page.

Get Facebook Page Access Token from the User or Page

Next, click Continue

Select the page you need and save the ID for further posting:

Both options have to be turned on. In our case Softacom. Click Further.

a Facebook page is linked to a Facebook app

The access token has been generated.

Testing the Facebook Graph API with the built-in debugging tool Graph API Explorer.

Now let’s test a GET request to get the profile name and identification number.

Select your page (Softacom)

Set up special permissions for posting (publish_to_groups, page_manage_posts).

 setup publish_to_groups and page_manage_posts permissions to start posting with Facebook API
 setup publish_to_groups and page_manage_posts permissions to start posting with Facebook API 2

Click “Generate Access Token” to generate an access token in order to save the permissions settings.

generate Facebook access token
Facebook access token is generated

Permissions are saved successfully and a new access token has been generated.

ALT text: Facebook access token is generated Filename: Facebook access token is generated 2

Now select your page from the list

select Facebook page in access token window

Send the GET request to get the page name and ID to ensure the Facebook Graph API works correctly.

Send a test POST request to add a post to the page in  form of a text message.

Send POST request to test Facebook Graph API

Now refresh the page and you should see the text message posted on the page.

check a test message posted with Facebook API

To delete a post, execute a DELETE request using the id of our post

DELETE request Facebook API JSON response

You should receive a response in JSON format telling that the post was deleted successfully.

DELETE request Facebook API JSON response 2

The previously received access token to the page is valid for an hour. To continue using the Facebook Graph API capabilities in Embarcadero Delphi’s FMX application, should be to obtain a long-term access token.

To get it, press “i” in front of our token.

obtain a long-term access token Facebook API

Next Open in Access Token Tool

 Open in Access Token Tool

Choose Extend Access Token

Extend Access Token Facebook Developer

Copy and save the resulting token

copy long-term access token Facebook API

For further usage of requests in the Embarcadero Delphi FMX application, you need to get the request body using Get Code

request body get code Facebook developer API
ALT text: request body get code Facebook developer API Filename: request body get code Facebook developer API 2

The request body must be copied and saved for later usage in Delphi. Similarly, can get the code of the remaining required requests.

Building an Embarcadero Delphi FMX app to post on a Facebook page 

To make requests to the Facebook API and receive a response in JSON format, use the TNetHttpRequest and TNetHttpClient components from the component palette (Net tab). They can be easily dragged onto the form. To work correctly, you need to change certain settings for the components. In the TNetHttpRequest component, in the Client field, select the current TNetHttpClient component that was added to the form along with TNetHttpRequest. You also need to set the MethodString parameter to POST.

TNetHttpRequest and TNetHttpClient to make requests and receive a response in JSON

To enter messages use the TMemo component.

TMemo component

TEdit components are used to enter image URLs, links for posting on a Facebook page. To enter an id, by which you’ll be able to delete a post from the page in future if needed, also use the TEdit component.

TEdit component to enter image URLs

The response from the server in the form of JSON will be stored in the TMemo component.

TMemo component to store server response in JSON format

In the onCreate form event handler, we assign the page access token to a variable of type string (token)

assign Facebook page access token

The text message entered by the user is stored in the “mes” string variable.

The post parameters (message, link, image url) are passed using a POST request to the Facebook Graph API server. Delphi uses the TMultiPartFormData class to send data using the POST method.

TMultiPartFormData class to send data using the POST method

Next, the request with parameters is sent using the NetHttpRequest POST method, where the input parameters are the url address of the server, an object of the TMultipartFormData type with parameters to pass to the server, and a TMemoryStream object to store the data received from the server.

NetHttpRequest POST method

Code snippets of button handlers for posting a simple text message, updating a post, posting an image url, deleting a post, posting a message and a link are given below.

// Post simple message to Facebook Page

procedure TForm1.btnPostMessageClick(Sender: TObject);

begin

  mes := MessageMemo.Text;

  TTask.Run(

    procedure

    var

      LMultipartFormData: TMultipartFormData;

      LMS: TMemoryStream;

    begin

      LMultipartFormData := TMultipartFormData.Create;

      LMultipartFormData.AddField(‘message’, mes);

      LMS := TMemoryStream.Create;

      NetHTTPRequest1.Post

        (‘https://graph.facebook.com/v12.0/103766905472273/feed?message&access_token=’

        + token, LMultipartFormData, LMS);

      TThread.Synchronize(nil,

        procedure

        begin

          ResponseMemo.Lines.LoadFromStream(LMS);

          TabControl1.GotoVisibleTab(1)

        end);

      LMS.Free;

      LMultipartFormData.Free;

    end);

end;

// Post url picture to Facebook Page

procedure TForm1.btnPostPictureClick(Sender: TObject);

begin

  TTask.Run(

    procedure

    var

      LMultipartFormData: TMultipartFormData;

      LMS: TMemoryStream;

    begin

      LMultipartFormData := TMultipartFormData.Create;

      LMultipartFormData.AddField(‘url’, EditURLPicture.Text);

      LMS := TMemoryStream.Create;

      NetHTTPRequest1.Post

        (‘https://graph.facebook.com/v12.0/103766905472273/photos?url&access_token=’

        + token, LMultipartFormData, LMS);

      TThread.Synchronize(nil,

        procedure

        begin

          ResponseMemo.Lines.LoadFromStream(LMS);

          TabControl1.GotoVisibleTab(1)

        end);

      LMS.Free;

      LMultipartFormData.Free;

    end);

end;

// Delete post by Id

procedure TForm1.btnDeleteClick(Sender: TObject);

begin

  TTask.Run(

    procedure

    var

      LMS: TMemoryStream;

    begin

      LMS := TMemoryStream.Create;

      NetHTTPRequest1.Delete(‘https://graph.facebook.com/v12.0/’ + Edit2.Text +

        ‘?access_token=’ + token, LMS);

      TThread.Synchronize(nil,

        procedure

        begin

          ResponseMemo.Lines.LoadFromStream(LMS);

          TabControl1.GotoVisibleTab(1)

        end);

      LMS.Free;

    end);

end;

// Post Message and link to Facebook Page

procedure TForm1.btnUpdateClick(Sender: TObject);

begin

  mes := MessageMemo.Text;

  TTask.Run(

    procedure

    var

      LMultipartFormData: TMultipartFormData;

      LMS: TMemoryStream;

    begin

      LMultipartFormData := TMultipartFormData.Create;

      LMultipartFormData.AddField(‘message’, mes);

      LMS := TMemoryStream.Create;

      NetHTTPRequest1.Post(‘https://graph.facebook.com/v12.0/’ + Edit2.Text +

        ‘?message&access_token=’ + token, LMultipartFormData, LMS);

      TThread.Synchronize(nil,

        procedure

        begin

          ResponseMemo.Lines.LoadFromStream(LMS);

          TabControl1.GotoVisibleTab(1)

        end);

      LMS.Free;

      LMultipartFormData.Free;

    end);

end;

procedure TForm1.btnMessageLinkPostClick(Sender: TObject);

begin

  mes := MessageMemo.Text;

  link := Edit3.Text;

  TTask.Run(

    procedure

    var

      LMultipartFormData: TMultipartFormData;

      LMS: TMemoryStream;

    begin

      LMultipartFormData := TMultipartFormData.Create;

      LMultipartFormData.AddField(‘message’, mes);

      LMultipartFormData.AddField(‘link’, link);

      LMS := TMemoryStream.Create;

      NetHTTPRequest1.Post

        (‘https://graph.facebook.com/v12.0/103766905472273/feed?message&link&access_token=’

        + token, LMultipartFormData, LMS);

      TThread.Synchronize(nil,

        procedure

        begin

          ResponseMemo.Lines.LoadFromStream(LMS);

          TabControl1.GotoVisibleTab(1)

        end);

      LMS.Free;

      LMultipartFormData.Free;

    end);

end;

The app’s operation on the MSWindows platform is shown below. Posting a simple text message

Below is the result of posting a text message on the Softacom page

The result of posting a text message and a link on the Softacom page

If desired, you can delete the post from the Facebook page using post Id. To do this, use the capabilities of the FMX application.

Enter Id and click “Delete post by id”.

The post on the Softacom page has been successfully deleted.

Watch step by step guide on our youtube channel

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