Mastering Field-Level Security in Sitecore XM Cloud: Why Your 'Field Write' Option is Missing
As Sitecore architects, we often face a specific requirement: Read-Only Fields. Whether you are pulling product data from a PIM, customer IDs from a CRM, or metadata from an external ERP, you need those fields to be visible to Content Authors but strictly uneditable. The goal is simple: the external system is the "Source of Truth," and manual edits in Sitecore would cause data desync.
Recently, a common hurdle has surfaced in XM Cloud environments regarding Field Write permissions. Let’s dive into why this happens and how to fix it.
The Challenge
Typically, to make a field read-only across an entire site, we:
Open the Security Editor.
Enable the Field Write column.
Deny Field Write on the Template item, expecting it to propagate to all content items.
The Problem: Many developers report that while they can see the "Field Write" column, the option to actually assign a "Deny" or "Grant" is missing when selecting the Template item itself.
Why is "Field Write" Missing?
As highlighted in a recent support case, the availability of field-level security depends on inheritance.
Field-level restrictions (Field Read/Field Write) only appear on items that inherit from the standard Sitecore Template system (specifically /sitecore/templates/System/Templates/Template field).
If you are looking at a Template Item (the "folder" icon that holds your sections), Sitecore traditionally treats "Write" and "Field Write" differently.
Write: Controls if you can edit the Template definition.
Field Write: Controls if you can edit the values inside the fields.
If you don't see the checkbox for Field Write on your base template, it usually means the Security Editor is filtering the available rights based on the template of the item you have selected.
Ways to Solve the "Read-Only" Requirement
The Security Editor (The Best Practice) To do this correctly via the UI:
Ensure you are in the Security Editor.
Click Columns in the Home tab and ensure Field Write is checked.
Crucial: Instead of trying to set it on the "Template" item, navigate one level deeper to the Template Field items themselves.
Deny Field Write to the sitecore\Sitecore Client Authoring role.
Why "Protect Item" is NOT the answer
A common mistake is using the "Protect Item" feature on a template.
Protect Item makes the item itself (the blueprint) read-only.
It does not propagate to the content items. Your authors will still be able to edit the fields on the pages, they just won't be able to change the name of the field in the template.
Summary
When dealing with external data in XM Cloud:
Use Field Write denials for role-based restrictions.
Use the Read Only checkbox on the field definition for global restrictions.
Always verify your work using the Access Viewer while masquerading as a non-admin user!
Key Takeaways for your Team: Admins bypass security: You will never see a field as "Read Only" if you are logged in as a System Admin.
Inheritance matters: Field-level security is a specialized right that only applies to items intended to hold data.
External Systems: If a field is managed by an API, lock it down early to prevent "Shadow Data" from being created by authors.