Troubleshooting

“has evaluated to null or missing” errors

Template error in login.ftl: The following has evaluated to null or missing:
==> realm.password  [in template "login.ftl" at line 2, column 109]

This means a FreeMarker template references a variable that doesn’t exist in the mock data. In a real Keycloak instance these variables are populated by the server — in Fitcloak you provide them via JSON.

Fix 1: Add the missing variable to mock data

Open your theme’s mock-data.json (or config.json) and add the missing field:

{
  "realm": {
    "name": "my-realm",
    "password": true
  }
}

Common realm fields that Keycloak templates expect:

Field	Type	Typical value	Used by
password	boolean	true	login.ftl — controls whether the password form is shown
registrationAllowed	boolean	true	login.ftl — “Register” link
resetPasswordAllowed	boolean	true	login.ftl — “Forgot password” link
rememberMe	boolean	true	login.ftl — “Remember me” checkbox
loginWithEmailAllowed	boolean	true	login.ftl — username field label
registrationEmailAsUsername	boolean	false	login.ftl — username field label
internationalizationEnabled	boolean	false	template.ftl — language selector

Fix 2: Override per-request via URL query parameters

Useful for quick testing without editing files:

http://localhost:3030/login?realm.password=true&realm.rememberMe=false

Fix 3: Use FreeMarker defaults in your templates

If you’re writing custom .ftl files, use the ! (default) operator to guard against missing values:

<#-- Instead of: -->
<#if realm.password>

<#-- Use a default value: -->
<#if (realm.password)!true>

The ! operator provides a fallback when the value is missing. (realm.password)!true means “use realm.password if it exists, otherwise true”.

Finding which variables a template needs

Keycloak templates reference many variables (realm, url, auth, login, social, properties, etc.). When you override or add a new .ftl file, you may need to provide additional mock values.

Approach: look at the .ftl file, find all ${...} expressions and <#if ...> conditions, then make sure each referenced object exists in your mock data. The demo’s mock-data.json is a good starting point to copy from.