Azure AD B2C - Claims transformation with 'StringSubstring'

Question

Hi,

We have single-sign-on solution based on Azure AD B2C. We also have multiple IDP's integrated through custom policies.

One of the IDP is Auth0 and Auth0 has some other internal federations.

When user is trying to sign in through Auth0(using federations) we are getting 'objectId' in a below format depeding upon the provider in Auth0.

"oidc|SSOOne-B2C-DEV|c25c18d4-fc36-4463-42bb-6b0662dc54b4",

or

"auth0|65ef9dcfa63cb1d97f580f9d"

We want to cut the part before the last occurance of the pipe '|' operator and get the remaining part.

We have a substring but not sure how to get the index of the last position of a pipe '|' operator and cut the string after that.

The output we want in above cases is

"c25c18d4-fc36-4463-42bb-6b0662dc54b4"

or

"65ef9dcfa63cb1d97f580f9d"

I have referred the ClaimTransformation for StringSubString but couldn't find the exact way to get it.

<ClaimsTransformation Id="GetCodePrefix" TransformationMethod="StringSubstring">
        <InputClaims>
          <InputClaim ClaimTypeReferenceId="objectId" TransformationClaimType="inputClaim" />
        </InputClaims>
        <InputParameters>
          <InputParameter Id="startIndex" DataType="int" Value="0" />
          <InputParameter Id="length" DataType="int" Value="24" />
        </InputParameters>
        <OutputClaims>
          <OutputClaim ClaimTypeReferenceId="objectId" TransformationClaimType="outputClaim" />
        </OutputClaims>
      </ClaimsTransformation>

Any input to transform the value "oidc|SSOOne-B2C-DEV|c25c18d4-fc36-4463-42bb-6b0662dc54b4" to "c25c18d4-fc36-4463-42bb-6b0662dc54b4"

Or

"auth0|65ef9dcfa63cb1d97f580f9d" to "65ef9dcfa63cb1d97f580f9d"

Thanks.

Answer 1

Hi @Gangarde, Sachin , you can use the StringLastIndexOf transformation method to get the index of the last occurrence of the pipe '|' operator and then use the StringSubstring transformation method to get the remaining part of the string. Here is an example:

<ClaimsTransformation Id="GetObjectId" TransformationMethod="StringSubstring">
  <InputClaims>
    <InputClaim ClaimTypeReferenceId="objectId" TransformationClaimType="inputClaim" />
  </InputClaims>
  <InputParameters>
    <InputParameter Id="startIndex" DataType="int" Value="{StringLastIndexOf:objectId, '|'}" />
    <InputParameter Id="length" DataType="int" Value="{StringLength:objectId}" />
  </InputParameters>
  <OutputClaims>
    <OutputClaim ClaimTypeReferenceId="objectId" TransformationClaimType="outputClaim" />
  </OutputClaims>
</ClaimsTransformation>

This transformation method first uses the StringLastIndexOf transformation method to get the index of the last occurrence of the pipe '|' operator in the objectId claim. The result of this transformation method is then used as the startIndex input parameter for the StringSubstring transformation method. The length input parameter is set to the length of the objectId claim. The result of the StringSubstring transformation method is then stored in the objectId claim. This will give you the desired output. Please let me know if you have any questions and I can help you further.

If this answer helps you please mark "Accept Answer" so other users can reference it.

Thank you,

James