Your First Changes

Now that you can explore a project with SHOW and DESCRIBE, it’s time to make changes. This chapter walks through the three most common modifications: creating an entity, a microflow, and a page.

Before you start

Always work on a copy. mxcli writes directly to your .mpr file. Before making changes, either:

Copy the .mpr file (and mprcontents/ folder if it exists) to a scratch directory
Use Git so you can revert with git checkout

# Make a working copy
cp app.mpr app-scratch.mpr
cp -r mprcontents/ mprcontents-scratch/   # only for MPR v2 projects

The workflow

Every modification follows the same pattern:

Write MDL – either directly on the command line with -c, or in a .mdl script file
Check syntax – run mxcli check to catch errors before touching the project
Execute – apply the changes to the .mpr file
Validate – use mxcli docker check for a full Studio Pro-level validation
Open in Studio Pro – confirm the result visually

# Step 1-2: Write and check syntax
mxcli check setup.mdl

# Step 3: Execute against the project
mxcli exec setup.mdl -p app.mpr

# Step 4: Full validation
mxcli docker check -p app.mpr

# Step 5: Open in Studio Pro and inspect

You can also skip the script file and execute commands directly:

mxcli -p app.mpr -c "CREATE PERSISTENT ENTITY MyModule.Product (Name: String(200) NOT NULL, Price: Decimal);"

What we’ll build

Over the next few pages, you’ll create:

What	MDL statement	Page
A `Product` entity with attributes	`CREATE PERSISTENT ENTITY`	Creating an Entity
A microflow that creates products	`CREATE MICROFLOW`	Creating a Microflow
An overview page listing products	`CREATE PAGE`	Creating a Page

The final page, Validating with mxcli check, covers the full validation workflow in detail.

Quick note on module names

Every MDL statement references a module. In these examples we use MyModule – replace it with whatever module exists in your project. You can check available modules with:

mxcli -p app.mpr -c "SHOW MODULES"

Idempotent scripts with OR MODIFY

If you plan to run a script more than once (common during development), use CREATE OR MODIFY instead of plain CREATE. This updates the entity if it already exists instead of failing:

CREATE OR MODIFY PERSISTENT ENTITY MyModule.Product (
    Name: String(200) NOT NULL,
    Price: Decimal,
    IsActive: Boolean DEFAULT true
);

The OR MODIFY variant is available for entities, enumerations, microflows, and pages. You’ll see it used throughout the tutorial.