Blazor WASM Authentication - TryGetToken is null - Version 3.2.0-preview2.20160.5

[aletc1]

Describe the bug

Using MSAL (With Azure Active Directory), after a successful login (when calling AuthenticationService.RequestAccessToken, the method tokenResult.TryGetToken(out var token) returns a null token value.

To Reproduce

Just generate a new MSAL project using:

dotnet new blazorwasm -au SingleOrg --client-id "{CLIENT ID}" --tenant-id "{TENANT ID}"

And to reproduce, consider the following code in index.razor

@code {

    protected override async Task OnInitializedAsync()
    {
        var tokenResult = await AuthenticationService.RequestAccessToken();
        
        if (tokenResult.TryGetToken(out var token))
        {
            if (token == null)
                throw new Exception("Access token is null. BUG?");
        }
    }
}

token shouldnt be null, since was successfully authenticated.

[miri10134]

I was about to open an issue for the same problem. On trying to understand the source of the problem I looked into the source code of the Interop/AuthenticationService-Class and found the following:

async getAccessToken(request?: AccessTokenRequestOptions): Promise<AccessTokenResult> {
        try {
            const newToken = await this.getTokenCore(request?.scopes);

            return {
                status: AccessTokenResultStatus.Success,
                token: newToken
            };

        } catch (e) {
            return {
                status: AccessTokenResultStatus.RequiresRedirect
            };
        }
    }

    async getTokenCore(scopes?: string[]): Promise<AccessToken | undefined> {
        const tokenScopes = {
            redirectUri: this._settings.auth.redirectUri as string,
            scopes: scopes || this._settings.defaultAccessTokenScopes
        };

        try {
            const response = await this._msalApplication.acquireTokenSilent(tokenScopes);
            return {
                value: response.accessToken,
                grantedScopes: response.scopes,
                expires: response.expiresOn
            };
        } catch (e) {
            return undefined;
        }
    }

getTokenCore catches every exception and just returns undefined, which is not checked in getAccessToken. This leads to a result where "status" is set to "Success", but "token" is empty. The outer catch-block (in getAccessToken) will probalby never be reached.

This does not explain the actual error but it is something that should be addressed along the way.

Edit:
The getAccessToken-Method in WebAssembly.Authentication looks better and does basically the same except for the underlying _userManager instead of _msalApplication. Maybe adopt this one to make them consistent?

[MortenMeisler]

Holy moly this was driving me crazy!! Is this fixed in pv 4 shipping 6th Apr? Maybe obvious not sure 💯 Any workarounds untill then?