B4J: creating a reCAPTCHA component in ABMaterial

reCAPTCHA is a free service that protects your website from spam and abuse. reCAPTCHA uses an advanced risk analysis engine and adaptive CAPTCHAs to keep automated software from engaging in abusive activities on your site. It does this while letting your valid users pass through with ease.

First, we do have to register a Google API key for our WebApp here.

After registering, we receive our API key:
For this demo, I’m using the developer API key (which works with localhost) so it will show a warning that this is not the real key in red.
NOTE: this code is for ABMaterial 3.75. For earilier versions, see below what needs to be changed in the code.

Create a new class CompReCAPTCHA:

'Class module
Sub Class_Globals
   Public ABMComp As ABMCustomComponent
   Dim mAPIKey As String
End Sub

'Initializes the object. You can add parameters to this method if needed.
Public Sub Initialize(InternalPage As ABMPage, ID As String, APIKey As String)
   ABMComp.Initialize("ABMComp", Me, InternalPage, ID, "")
   mAPIKey = APIKey
End Sub
Sub ABMComp_Build(InternalPage As ABMPage, internalID As String) As String
   Return $"
<div id="${internalID}render" class="g-recaptcha" data-sitekey="${mAPIKey}"></div>
"$
End Sub
' Is useful to run some initalisation script.
Sub ABMComp_FirstRun(InternalPage As ABMPage, internalID As String)
   Dim script As String = $"grecaptcha.render(
"${internalID}render",
{"sitekey": "${mAPIKey}", "theme": "light"}
) "$
   InternalPage.ws.Eval(script, Array As Object(ABMComp.ID))
   ' flush not needed, it's done in the refresh method in the lib
End Sub

public Sub Reset(InternalPage As ABMPage)
   Dim script As String = $"grecaptcha.reset()"$
   InternalPage.ws.Eval(script, Null)
   InternalPage.ws.Flush
End Sub

public Sub CheckValidation(InternalPage As ABMPage) As Boolean
   Dim script As String = $"return (grecaptcha && grecaptcha.getResponse().length !== 0);"$
   Dim ret As Future = InternalPage.ws.EvalWithResult(script, Null)
   InternalPage.ws.Flush

   Return ret.Value
End Sub
' runs when a refresh is called
Sub ABMComp_Refresh(InternalPage As ABMPage, internalID As String)
   Dim script As String = $""$
   InternalPage.ws.Eval(script, Array As Object(ABMComp.ID))
End Sub
' do the stuff needed when the object is removed
Sub ABMComp_CleanUp(InternalPage As ABMPage, internalID As String)
End Sub

In BuildPage(), add the Google api:

page.AddExtraJavaScriptFile("<a class="linkification-ext" title="Linkification: https://www.google.com/recaptcha/api.js" href="https://www.google.com/recaptcha/api.js">https://www.google.com/recaptcha/api.js</a>")

In Class_Globals make a variable:

Dim myReCAPTCHA As CompReCAPTCHA

In ConnectPage create the component (and a couple of buttons):

...
' note that this is Googles demo API key.  Use your own!
myReCAPTCHA.Initialize(page, "myReCAPTCHA", "6LeIxAcTAAAAAJcZVRqyHh71UMIEGNQ_MXjiZKhI")
page.Cell(1,1).AddComponent(myReCAPTCHA.ABMComp)

Dim btn As ABMButton
btn.InitializeFlat(page, "btn", "", "", "Submit", "")
page.Cell(1,1).AddComponent(btn)

Dim btn2 As ABMButton
btn2.InitializeFlat(page, "btn2", "", "", "Reset", "")
page.Cell(1,1).AddComponent(btn2)

' refresh the page
page.Refresh
...

The code in the buttons to check its validation and to reset the captcha.

Sub btn_Clicked(Target As String)
   Dim bool As Boolean = myReCAPTCHA.CheckValidation(page)
   Log(bool)
End Sub

Sub btn2_Clicked(Target As String)
   myReCAPTCHA.Reset(page)
End Sub

Et voila, we do have a new reCAPTCHA component at our disposal in ABMaterial!

For ABMaterial pre 3.75, make these changes in the code:

Public Sub Initialize(InternalPage As ABMPage, ID As String, APIKey As String)
   ABMComp.Initialize("ABMComp", Me, InternalPage, ID) ' last param removed
   mAPIKey = APIKey
End Sub
...
Sub ABMComp_Build( internalID As String) As String ' InternalPage param removed
   Return $"
<div id="${internalID}render" class="g-recaptcha" data-sitekey="${mAPIKey}"></div>
"$
End Sub

Until next Time!

Alwaysbusy

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About Alwaysbusy

My name is Alain Bailleul and I'm the Senior Software Architect/Engineer at One-Two. I like to experiment with new technologies, Computer Vision and A.I. My projects are programmed in B4X , Xojo, C#, java, HTML, CSS and JavaScript. View all posts by Alwaysbusy

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