Fix: Authentication fails with 422 error due to incorrect request body format

[romzes5000]

Hi! 👋

Firstly, thanks for your work on this project! 🙂

Today I used patch-package to patch @montarist/airalo-api@1.0.4 for the project I'm working on.

The authenticate method in AiraloService fails when attempting to retrieve an access token from the /v2/token endpoint, resulting in a 422 Unprocessable Entity error.

Problem:

The method currently attempts to send the authentication credentials (client_id, client_secret, grant_type) using a FormData object. Debugging showed that when axios sends this request, the actual request body received by the server is effectively empty (data: {} in internal axios config logs), even though the FormData object is populated correctly in the client-side code. This mismatch causes the Airalo API to reject the request with a 422 error because the required fields are missing from the body it parses.

Attempts to manually set the Content-Type: multipart/form-data header resulted in a "Missing boundary" error, indicating further incompatibility with how the server expects the data for this specific endpoint.

Solution:

The /v2/token endpoint appears to expect the credentials either as application/json or application/x-www-form-urlencoded, but not multipart/form-data.

The fix involves changing the authenticate method to pass a plain JavaScript object containing client_id, client_secret, and grant_type as the data payload for the axios.post request, instead of using FormData. This allows axios to correctly serialize the data (likely as application/json or x-www-form-urlencoded by default for plain objects), which the API endpoint successfully processes.

The provided diff implements this change in both the compiled JavaScript (dist/) and the source TypeScript (src/) files, resolving the authentication failure.

Here is the diff that solved my problem:

diff --git a/node_modules/@montarist/airalo-api/dist/services/airalo.service.js b/node_modules/@montarist/airalo-api/dist/services/airalo.service.js
index 7e70be0..1f18a5e 100644
--- a/node_modules/@montarist/airalo-api/dist/services/airalo.service.js
+++ b/node_modules/@montarist/airalo-api/dist/services/airalo.service.js
@@ -55,11 +55,11 @@ class AiraloService {
         }
     }
     async authenticate() {
-        const formData = new FormData();
-        formData.append('client_id', this.config.clientId);
-        formData.append('client_secret', this.config.clientSecret);
-        formData.append('grant_type', 'client_credentials');
-        const response = await this.handleRequest(() => this.axiosInstance.post('/v2/token', formData));
+        const response = await this.handleRequest(() => this.axiosInstance.post('/v2/token', {
+            client_id: this.config.clientId,
+            client_secret: this.config.clientSecret,
+            grant_type: 'client_credentials'
+        }));
         this.accessToken = response.data.access_token;
     }
     async getOrders(params) {
diff --git a/node_modules/@montarist/airalo-api/src/services/airalo.service.ts b/node_modules/@montarist/airalo-api/src/services/airalo.service.ts
index 5e61442..9929ba2 100644
--- a/node_modules/@montarist/airalo-api/src/services/airalo.service.ts
+++ b/node_modules/@montarist/airalo-api/src/services/airalo.service.ts
@@ -137,13 +137,12 @@ export class AiraloService {
      * @throws {AiraloError} If authentication fails
      */
     async authenticate(): Promise<void> {
-        const formData = new FormData();
-        formData.append('client_id', this.config.clientId);
-        formData.append('client_secret', this.config.clientSecret);
-        formData.append('grant_type', 'client_credentials');
-
         const response = await this.handleRequest<AiraloAuthResponse>(() =>
-            this.axiosInstance.post('/v2/token', formData),
+            this.axiosInstance.post('/v2/token', {
+                client_id: this.config.clientId,
+                client_secret: this.config.clientSecret,
+                grant_type: 'client_credentials'
+            }),
         );
 
         this.accessToken = response.data.access_token;

This issue body was partially generated by patch-package.