Customisation of sign up page in ADB2C custom policy - azure-ad-b2c

Question

We are using custom policy and are have added some fields in the signup page. We have a DateTimeDropdown claim type to allow a user to select date of birth. Below is the policy configuration for the claim:
<ClaimType Id="birthDate">
<DisplayName>Birth Date</DisplayName>
<DataType>date</DataType>
<DefaultPartnerClaimTypes>
<Protocol Name="OAuth2" PartnerClaimType="birth_date" />
<Protocol Name="OpenIdConnect" PartnerClaimType="birth_date" />
<Protocol Name="SAML2" PartnerClaimType="http://schemas.xmlsoap.org/ws/2005/05/identity/claims/birthdate" />
</DefaultPartnerClaimTypes>
<UserInputType>DateTimeDropdown</UserInputType>
</ClaimType>
This is how it renders on the page.
The Year selection gives a range starting from 1900 and goes up to 2050. Is there any way to configure to alter or limit the values present in this dropdown?

Answer 1

This can be done using Predicates and PredicateValidations.
Update your ClaimType to include a PredicateValidation;
<ClaimType Id="birthDate">
<DisplayName>Birth Date</DisplayName>
<DataType>date</DataType>
<DefaultPartnerClaimTypes>
<Protocol Name="OAuth2" PartnerClaimType="birth_date" />
<Protocol Name="OpenIdConnect" PartnerClaimType="birth_date" />
<Protocol Name="SAML2" PartnerClaimType="http://schemas.xmlsoap.org/ws/2005/05/identity/claims/birthdate" />
</DefaultPartnerClaimTypes>
<UserInputType>DateTimeDropdown</UserInputType>
<PredicateValidationReference Id="CustomDateRange" />
</ClaimType>
Then add the following in between </ClaimsSchema> and <ClaimsTransformation>;
<Predicates>
<Predicate Id="DateRange" Method="IsDateRange" HelpText="The date must be between 1920-01-01 and today.">
<Parameters>
<Parameter Id="Minimum">1920-01-01</Parameter>
<Parameter Id="Maximum">Today</Parameter>
</Parameters>
</Predicate>
</Predicates>
<PredicateValidations>
<PredicateValidation Id="CustomDateRange">
<PredicateGroups>
<PredicateGroup Id="DateRangeGroup">
<PredicateReferences>
<PredicateReference Id="DateRange" />
</PredicateReferences>
</PredicateGroup>
</PredicateGroups>
</PredicateValidation>
</PredicateValidations>