Looking to have Azure B2C custom policy use a custom error page (and pass a value) - azure

Question

UPDATE:
I am able to finally get my custom error page to render. I had to use
<div id="api"></div>
in my view.
My last concern here, which seems impossible, is adding the value of one of my claims (from the idToken passed to my B2C policy when I call it) into the LoadUri of my ContentDefintion.
Here are my TechnicalProfiles:
<TechnicalProfile Id="SelfAsserted-SigningNotReadyError">
<InputClaimsTransformations>
<InputClaimsTransformation ReferenceId="GetUser" />
</InputClaimsTransformations>
<IncludeTechnicalProfile ReferenceId="SelfAsserted-UserError" />
</TechnicalProfile>
<TechnicalProfile Id="SelfAsserted-UserError">
<DisplayName>Unsolicited error message</DisplayName>
<Protocol Name="Proprietary" Handler="Web.TPEngine.Providers.SelfAssertedAttributeProvider, Web.TPEngine, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
<Metadata>
<Item Key="ContentDefinitionReferenceId">api.signingerrorlink</Item>
</Metadata>
<InputClaims>
<InputClaim ClaimTypeReferenceId="errorMessage" />
</InputClaims>
<OutputClaims>
<OutputClaim ClaimTypeReferenceId="errorMessage" />
</OutputClaims>
</TechnicalProfile>
and my ContentDefinition
Note: see how I have to hardcode a GUID. :(
signingerror?user=7ec00437-1ad9-4acc-a285-a729003ca99d
<ContentDefinition Id="api.signingerrorlink">
<LoadUri>https://something.azurewebsites.net/signingerror?user=7ec00437-1ad9-4acc-a285-a729003ca99d</LoadUri>
<RecoveryUri>https://something.azurewebsites.net/error</RecoveryUri>
<DataUri>urn:com:microsoft:aad:b2c:elements:contract:selfasserted:1.2.0</DataUri>
<Metadata>
<Item Key="DisplayName">Signing Not Ready</Item>
</Metadata>
</ContentDefinition>
ORIGINAL:
I'm in a pickle here. I have been looking through many posts in stackoverflow and over the internet in general. I hope you can help me.
I have a custom B2C policy, which basically accepts a token, performs some functions then returns an access token in the end. That works fine. My issue is that I need to define a step which will trigger a techical profile based on a precondition. The precondition actually works well to.
What I am missing is a way to construct a technicalprofile/contentdefinition to load my own error page (.Net Core 3 controller) in another project but totally accessible (Controllers/SigningErrorController).
My step:
<OrchestrationStep Order="7" Type="ClaimsExchange">
<Preconditions>
<Precondition Type="ClaimEquals" ExecuteActionsIf="true">
<Value>isReadyForSigning</Value>
<Value>True</Value>
<Action>SkipThisOrchestrationStep</Action>
</Precondition>
</Preconditions>
<ClaimsExchanges>
<ClaimsExchange Id="SelfAsserted-SigningNotReady" TechnicalProfileReferenceId="SelfAsserted-SigningNotReadyError" />
</ClaimsExchanges>
</OrchestrationStep>
Part 2! I need to pass a value to this custom error page. A guid in this case.
If I use the TP for invalidlink then this works. I have tried various custom contentdefinitions similar to:
<ContentDefinition Id="api.signingerrorlink">
<LoadUri>https://something.azurewebsites.net/error</LoadUri>
<RecoveryUri>https://something.azurewebsites.net/signingerror</RecoveryUri>
<DataUri>urn:com:microsoft:aad:b2c:elements:globalexception:1.1.0</DataUri>
<Metadata>
<Item Key="DisplayName">Error page</Item>
</Metadata>
</ContentDefinition>
...with the signingerror being the custom error page I want to go to.
If I run this, the policy just skips over the step completely. If I use the invalid link TP, then it works. I've tried to figure out also how to pass a value to the error page. I'm at a loss folks.
Any help you can give would be much appreciated.

Answer 1

You can use a claim resolver in the LoadUri element. E.g.:
<ContentDefinition Id="api.signingerrorlink">
<LoadUri>https://something.azurewebsites.net/signingerror?user={Claim:packageUserId}</LoadUri>
<RecoveryUri>https://something.azurewebsites.net/error</RecoveryUri>
<DataUri>urn:com:microsoft:aad:b2c:elements:contract:selfasserted:1.2.0</DataUri>
<Metadata>
<Item Key="DisplayName">Signing Not Ready</Item>
</Metadata>
</ContentDefinition>
https://learn.microsoft.com/en-us/azure/active-directory-b2c/claim-resolver-overview#content-definition