---
title: Object operations
description: "> Welcome to **Expert Tips **— a growing collection of practical tips and real-world examples to help you get the most out of Extension Kit Core. > > > > This page focuses on the **Object Operations** module group, which includes the following modules: **Object…"
url: "https://extensionkit.unitfly.com/documentation/expert-tips-object-operations/"
updated: "2025-11-28"
category: Resources / Expert tips
---

# Object operations

> Welcome to **Expert Tips **— a growing collection of practical tips and real-world examples to help you get the most out of Extension Kit Core.
>
>
>
> This page focuses on the **Object Operations** module group, which includes the following modules: **Object Operations, Object Templates, Extended Assignments, Validation, Versioning,**and **Extended Permissions.**

> To get a new expert tip delivered to your inbox every week, **subscribe to the Tip of the Week newsletter [here](https://pages.unitfly.com/extension-kit-newsletter-subscription).**

---

 Automate object creation from multi-select properties

## Automate object creation from multi-select properties

This tip explores how to **automatically create objects in M-Files based on values selected in a multi-select property.** It’s a great way to streamline your workflows and eliminate repetitive manual work.

**Example**

Let’s say you have a **Project** object with these properties: **Name, Budget, Deadline,** and a multi-select **Task list** template for creating objects.

Each project may include several tasks - and you want each of them to be managed as a separate object. Instead of creating those task objects manually, you can automate this process with Extension Kit Core.

**Configuration steps**

Use **advanced configuration mode** in the **Object Operations** module to set up a rule that creates a new object for every selected task in the **Task list** (Picture 1).

1. **Action type:** Set the action type to **Create** to generate new objects.
2. **New object setup:** In the **New objects** section, define the Object type, Object class, and any relevant properties for the new object.
3. **Advanced settings:** Under **New objects → Advanced settings**, you must specify the following to ensure each task is processed individually:
   - **Iterator property:** Specify the property on the source object that serves as an iterator. In this case, the **Task list** property acts as the iterator, as new objects need to be created for each selected task.
   - **Iterator item property:** Specify the property where the current task value should be stored in the new object, e.g. a **Task Name**.
   - **Iterator index property:** Specify the property on the new object that will store an index of the current iterator item. In this example, the index is stored in the **Iterator** property on the OT **Task**.
4. **Execution mode:** Set it to **Background** or **BackgroundTransaction** to ensure the rule runs smoothly in the background.

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/07/Automate-object-creation-1-742x1024.png)
Picture 1: Rule configuration for creating individual Task objects from a multi-select Task list property.

**The result in M-Files**

Let’s say you select ten tasks in the **Task list** of your **Demo Project** (see Picture 2).

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/07/Automate-object-creation-2.png)
Picture 2: A Demo Project object contains a multi-select Task list property.

Once the rule is triggered, 10 individual Task objects are automatically created - one for each selected task (see Picture 3). This setup saves time, reduces errors, and ensures every task is properly tracked in M-Files.

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/07/Automate-object-creation-3-1024x422.png)
Picture 3: A separate Task object is automatically created.

Automating object creation based on a multi-select property is a simple but powerful way to reduce manual effort and enhance overall efficiency in M-Files.

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 Creating error messages in the Validation module

## Creating error messages in the Validation module

In the Validation module, **error messages can be defined in** **two places,** and it’s helpful to understand how they work together.

**1. The general error message**

This message is set at the **module level** and will appear whenever **any condition in a Validation rule is not met** for an object. The default text is *Validation failed*, but you can customize it as needed (Picture 1).

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/10/Error-message-1-2.png)
Picture 1: A general error message for all failed rules in the module.

**2. The custom rule-specific message**

Optionally, within each Validation rule, you can **specify a custom error message** that appears below the general error. Note: The configuration mode within the **Property validation rules** section needs to be set to **Advanced** (Picture 2).

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/10/Error-message-2.png)
Picture 2: Specifying a custom error message.

**The result**

As a result, the error message will provide both a general alert and a rule-specific explanation for the user (Picture 3).

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/10/Error-message-3.png)
Picture 3: Example of an error message with a precise explanation.

**Summary: How these messages appear together**

- The **first message** (e.g., *An error has occurred*) comes from the module-level default message and shows for **every validation error**.
- The **second message** is **specific to the individual rule** that failed and explains what exactly went wrong.

To make validation error messages clearer, remember to customize both the default message and the rule-specific messages.

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 Enforce document creation from templates only

## Enforce document creation from templates only

Sometimes, you may want to ensure that certain documents are **created only from templates** in M-Files. This helps prevent assigning them to the wrong class, triggering the wrong workflow, or causing execution errors or incorrect assignments.

For example, let’s say you want documents of a specific class, like **Report**, to be created only through templates. The idea is simple: **validate whether a document was created from a template or not.**

Here’s how.

**Step 1: Add a property to control creation**

We’ll use a dedicated property to drive the validation rule.

In the **Metadata Card Configuration:**

- **Add a new property** to the class (e.g., `FromTemplate`).
- Set its **default value** to `No`.
- Hide the property and make it **read-only.**

With this setup (Picture 1), every new Report document will automatically get `FromTemplate = No` whenever it’s created via any standard create action in M-Files (and not Create from template).

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/10/templates-creation-1-1024x787.png)
Picture 1

Next, create a **template** for the Report class with this property set to `Yes` (Picture 2).

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/10/templates-creation-2-1024x843.png)
Picture 2

This means:

- Documents created from a template will have `FromTemplate = Yes`.
- All other creation methods will result in `FromTemplate = No`.

**Step 2: Restrict creation to templates**

Finally, configure a **validation rule** (Picture 3) in the **Validation** module of Extension Kit Core:

- Rule checks if `FromTemplate = Yes` for the Report class.
- If not, display an error message and prevent creation.

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/10/templates-creation-3-654x1024.png)
Picture 3

**The result**

Users can only create documents of that class through templates. If they try another way, a validation message prevents creation (Picture 4).

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/10/templates-creation-4.png)
Picture 4

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 Duplicates Detection in Extension Kit Core

## Duplicates Detection in Extension Kit Core

When importing or creating objects in M-Files, you may need to prevent the creation of duplicate objects. With Extension Kit Core’s **Duplicate detection**, you can automatically check if an object with the same property value already exists, and decide whether to create, skip, or update it.

**What is Duplicates detection?**

**Duplicates detection** lets you define which properties determine if an object is a duplicate. In other words, you can specify a **set of properties that must be unique** for objects of a specific type.

This feature is available in the following modules: **Data Transfer, Object Operations, Excel Reader, and HTTP Integration.**

**Example**

Let’s say you’re importing conference participants from an Excel file.

In M-Files, there’s a class called **Participant**, with properties such as *Name*, *Address*, and *OIB (Personal ID)*. Since the OIB must be unique for every person, it’s perfect for duplicate detection.

When the rule runs, Extension Kit Core will:

1. Read the OIB from each Excel row.
2. Check if an object with that OIB already exists in M-Files.
3. If it doesn’t, create a new object.
4. If it does, skip the row to avoid creating a duplicate.

**Configuration by module**

Each module has its own configuration options for handling duplicates, but the logic is the same: detect, compare, and decide what to do.

a) **Object Operations**

When creating objects, you can define properties that must be unique and choose how duplicates are handled (Duplicate object behavior):

- **Overwrite:** Update existing objects.
- **Skip:** Ignore duplicates.
- **CreateNew:** Always create new objects.

If you choose *Overwrite*, you can specify whether to overwrite only metadata, only files, or both. (Picture 1)

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/10/Duplicates-1.png)
Picture 1

b) **Data Transfer**

When importing data from a file system to M-Files, you can enable Duplicates detection to ensure objects are unique. Define the unique properties, and choose how to handle duplicates: skip, overwrite, or create new objects (Picture 2).

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/10/Duplicates-2.png)
Picture 2

c) **HTTP Integration**

Duplicates detection defines how duplicate objects from an HTTP response are handled. In addition to skipping, overwriting, or creating new objects, you can also choose **Upsert** (creating new objects and overwriting existing ones).

In this module, duplicates are detected using a Duplicate search , where you define search filters to find existing objects, unlike other modules where duplicates are detected based on properties (Picture 3).

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/10/Duplicates-3.png)
Picture 3

d) **Excel Reader**

When mapping a range from an Excel file to M-Files, you can create objects from that range and prevent duplicates. Set properties that must be unique in the Excel data, and Extension Kit Core will skip duplicate rows or columns during import (Picture 4).

![](https://extensionkit.unitfly.com/wp-content/uploads/2025/10/Duplicates-4.png)
Picture 4

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