Exception while creating Card Token with cardId

[Surya Pratap Singh (suryapts007)]

Hi guys,
I am a software engineer from UnDosTres (Mexico).

Recently I was trying to integrate mercadopago-java SDK (v 2.1.7) with our system.
I was able to associate the card successfully with a customer and get a cardId in response.
But when I was trying to create a token with the received cardId, I was getting an exception from the SDK.

After digging into the SDK code I found that the problem is in line no 94 of the below screenshot.
CardToken cardToken = Serializer.deserializeFromJson(CardToken.class, response.getContent());

After digging a little more I found out that I am successfully receiving a 201 response code with JSON string having the tokenId in line no. 87. You can see it in the below screenshot.

But when we are trying to deserialize the JSON to a CardToken object, it throws an exception with the message
class com.mercadopago.resources.CardToken cannot be cast to class com.mercadopago.net.MPResource (com.mercadopago.resources.CardToken and com.mercadopago.net.MPResource are in unnamed module of loader 'app')

The problem is that Serializer.deserializeFromJson function expects a class that is a subtype of the MPResource class, but the class CardToken does not extend MPResource.

Well actually, CardToken does extend MPResource class, but just in the source code, not in the JAR file (which is kind of weird). Below is the screenshot of the same.

Can you guys please help us with this issue?

[Rhames Lima (rhames07)]

Hello Surya Pratap Singh (@suryapts007) !

Thank you for informing us about this problem, we will analyze it and get back to you as soon as possible.

[Rhames Lima (rhames07)]

Surya Pratap Singh (@suryapts007) I tried to reproduce your problem by creating a new project, downloading the SDK in version 2.1.17 and creating a card token, and everything worked fine. I suggest you try recompiling the SDK or the project and see if it works.
Also, even though it is possible to create the card token from the backend using the SDK Java, it is recommended that the card token is always created from the SDK JS for greater security reasons.

If you have any further questions, please let me know!

[Surya Pratap Singh (suryapts007)]

Hi Rhames Lima (@rhames07)
Also, even though it is possible to create the card token from the backend using the SDK Java, it is recommended that the card token is always created from the SDK JS for greater security reasons.
This line of yours suggest me that you are talking about the one time use token because that is the one we can generate from JS SDK.

But what I meant is not that token but the token we get in exchange to the cardId.
To be very precise, check the create() funciton inside CardTokenClient class.
That is where the problem is.

I have tried recompiling the project and the problem still persists.

For more clarity we can have a quick call as well if you agree.

[Rhames Lima (rhames07)]

Surya Pratap Singh (@suryapts007) ,

About the compilation error: since the recompilation didn't work, which is very strange, could you try using a different version (2.1.16 for example) and then go back to the current version (2.1.17) and see if the compilation problem is fixed?

Regarding my suggestion: the JS SDK can create a card token if you pass it the card id.

1. You should send the card id from the backend to the frontend.
2. Generate the card token in the frontend with the SDK JS using the card id and the CVV.
3. Send the card token to the backend to create the payment (then in the payment pass the customer id).

As I said, it's recommended to use the SDK JS to generate card tokens for security reasons.