ArcGISCredential.fromJson() throws exception "Null check operator used on a null value"

AM01

Hi All,

I am trying to add the credentials via ArcGISEnvironment.authenticationManager.arcGISCredentialStore.addForUri()

I have logged into the AGOL via WebView and after successful login. I am trying to add the credentials. I tried following,

      final credentialMap = {
        "token": token,
        "userId": username,
        "expiration": expireTime.toIso8601String(),
      };

      final tokenCredential = ArcGISCredential.fromJson(credentialMap);

      // Add credential to the store
     ArcGISEnvironment.authenticationManager.arcGISCredentialStore.addForUri(
        credential: tokenCredential,
        uri: Uri.parse(portalURL),
      );

      final portal = Portal.arcGISOnline(
        connection: PortalConnection.authenticated,
      );
      await portal.load();

 

I checked every thing none of value is null in credentialMap, but I am still getting an exception line no. 7 - "Null check operator used on a null value".

Not sure what I am missing here. Any help would be appreciated.

fyi, I successfully login and have the token and other user details, its just I want to use Portal APIs exposed by SDK. I am looking to get the license info so that app could work offline and use portal APIs. It appears there is no url to get the license via http call.

kossiyovo

You don't need to use WebView to login. You can do that directly through the Flutter Maps SDK using TokenCredential with this approach:

final credential = await TokenCredential.create(
  uri: Uri.parse(portalURL),
  username: username,
  password: password,
);

Add the credential to the credential store: This is where you were getting the null error. Use the TokenCredential directly:

ArcGISEnvironment.authenticationManager.arcGISCredentialStore.addForUri(
  credential: credential,  // Use the TokenCredential, not a JSON map
  uri: Uri.parse(portalURL),
);

Create and load the authenticated portal:

final portal = Portal.arcGISOnline(
  connection: PortalConnection.authenticated,
);
await portal.load();

Get the license info for offline functionality: This is what you need for offline Portal APIs:

final licenseInfo = await portal.fetchLicenseInfo();
print('License: ${licenseInfo.toJson()}');


// You'd get something like: {licenseString: LICENSE_KEY}

This should eliminate your null pointer exception and get you the offline licensing you're looking for.

Checkout this sample for a full example: https://github.com/Esri/arcgis-maps-sdk-flutter-samples/tree/main/lib/samples/authenticate_with_token

Let me know if you have any questions!