Metadata-based Permission Management in SharePoint

Introduction

In many business scenarios, content security in SharePoint Online cannot be managed solely at the site or document library level. Some documents or list items require a differentiated level of protection — for example, based on business division, document type, or confidentiality level.

In these cases, it is possible to implement a dynamic permission management based on metadata. SharePoint allows the use of custom columns (site columns or content type fields) as a logical trigger to automatically modify the permissions of a file or an item.

This article outlines a technical approach based on:

• Managed metadata to categorize documents.
• Power Automate flows for dynamic permission removal and assignment.
• PnP PowerShell and REST API for advanced automations.

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1. Logical Architecture

The basic principle is simple: every time a file is created or modified, SharePoint checks the value of one or more metadata and updates the permissions of the item based on predefined rules.

Practical example: If the metadata Department = Finance, then the item will be accessible only to the group Finance_Viewers.

Involved Components

1. Document Library with custom columns (e.g. Confidentiality, Department, Project).
2. Power Automate Flow with trigger When a file is created or modified (properties only).
3. SharePoint HTTP REST calls or dedicated Power Automate actions for managing permissions.

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2. Library Configuration

Create a document library or a custom list with the following columns:

These columns will become the key metadata for the security logic.

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3. Power Automate: automatic management of permissions

The most efficient way to manage dynamic security is to use a Power Automate flow.

a) Trigger

Use the connector:

When a file is created or modified (properties only)

Add a condition to check if the key metadata (Dipartimento, Riservatezza) has been modified.

b) Removal of inherited permissions

To avoid conflicts, you need to break the inheritance of permissions with a REST HTTP action:

POST https://{tenant}.sharepoint.com/sites/{site}/_api/web/lists/getbytitle('Documenti')/items(@{triggerOutputs()?['body/ID']})/breakroleinheritance(copyRoleAssignments=false, clearSubscopes=true)

c) Assignment of new permissions

After breaking inheritance, assign permissions based on the value of the metadata:

POST https://{tenant}.sharepoint.com/sites/{site}/_api/web/lists/getbytitle('Documenti')/items(@{triggerOutputs()?['body/ID']})/roleassignments/addroleassignment(principalid=@{variables('GroupID')}, roledefid=1073741826)

Where roledefid represents the permission level (1073741826 = Contribute, 1073741827 = Read, etc.).

You can map metadata values to M365 groups via a configuration table or a support SharePoint list.

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4. Example: dynamic permissions by department

Objective

Every document uploaded to the library must be accessible only to the group corresponding to the department selected in the metadata Dipartimento.

Solution

1. Column Department with values: IT, HR, Finance, Legal.
2. List AccessControl with mapping:

3. Power Automate flow that:

• Reads the value of Department.
  • Searches for the group ID in the AccessControl list.
  • Removes inherited permissions.
  • Assigns read-only permission to the corresponding group.

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5. Advanced Management with PnP PowerShell

For complex or massive implementations, you can use PnP PowerShell.

Example script

Connect-PnPOnline -Url "https://tenant.sharepoint.com/sites/Sicurezza" -Interactive

$items = Get-PnPListItem -List "Documenti Riservati"

foreach ($item in $items) {
    $dip = $item["Dipartimento"]
    $group = Get-PnPGroup -Identity "$dip-Viewers"
    Set-PnPListItemPermission -List "Documenti Riservati" -Identity $item.Id -AddRole "Read" -Group $group.Title -BreakRoleInheritance
}

This approach is ideal for:

• Massive updates.
• Periodic synchronizations from external systems.
• Scheduled automations via Azure Automation.

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6. Security and Performance Considerations

• Avoid too many items with unique permissions → SharePoint has limits (~50,000 unique items per list).
• Centralize the rules in a configuration list, so you can modify the criteria without rewriting the flows.
• Audit and logging: always save a log of permission changes for compliance reasons.
• Use Site Scripts or PowerShell to clone configurations between environments (UAT → Prod).

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7. Conclusion

Managing permissions in SharePoint based on metadata allows for an ideal balance between flexibility and security. By combining Power Automate, REST API, and PnP PowerShell, you can create an adaptive and scalable security system that can dynamically respond to organizational changes.

👉 Do you want to implement dynamic security based on metadata in your Microsoft 365 environment? Contact me for a personalized consultation or discover other solutions in the Office365 & SharePoint section.