topic Re: ArcGISCredential.fromJson() throws exception "Null check operator used on a null value" in Flutter Maps SDK Questions

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

AM01 — Wed, 16 Jul 2025 04:45:02 GMT

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.

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

kossiyovo — Sat, 19 Jul 2025 02:07:51 GMT

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!