Activity Types

This page documents every activity type available in MDL microflows. Activities are the individual steps that make up a microflow’s logic.

Object Operations

CREATE

Creates a new object of the specified entity type and assigns attribute values:

$Order = CREATE Sales.Order (
  OrderDate = [%CurrentDateTime%],
  Status = 'Draft',
  TotalAmount = 0
);

Attribute assignments are comma-separated Name = value pairs. The result is assigned to a variable.

CHANGE

Modifies attributes of an existing object:

CHANGE $Order (
  Status = 'Confirmed',
  TotalAmount = $CalculatedTotal
);

Multiple attributes can be changed in a single CHANGE statement.

COMMIT

Persists an object (or its changes) to the database:

COMMIT $Order;

Options:

• WITHOUT EVENTS – skips the event handlers (before/after commit microflows), which otherwise run
• REFRESH – refreshes the object in the client after committing

COMMIT $Order;
COMMIT $Order REFRESH;
COMMIT $Order REFRESH;

DELETE

Deletes an object from the database:

DELETE $Order;

ROLLBACK

Reverts uncommitted changes to an object, restoring it to its last committed state:

ROLLBACK $Order;
ROLLBACK $Order REFRESH;

The REFRESH option refreshes the object in the client.

Retrieval

RETRIEVE from Database (XPath)

Retrieves objects from the database using an optional XPath-style WHERE clause:

-- Retrieve a single object
RETRIEVE $Customer FROM Sales.Customer
  WHERE Email = $InputEmail
  FIRST;

-- Retrieve a list of objects
RETRIEVE $ActiveOrders FROM Sales.Order
  WHERE Status = 'Active';

-- Retrieve all objects of an entity
RETRIEVE $AllProducts FROM Sales.Product;

-- Retrieve with multiple conditions
RETRIEVE $RecentOrders FROM Sales.Order
  WHERE Status = 'Active'
  AND OrderDate > [%BeginOfCurrentDay%]
  LIMIT 50;

With FIRST the result is a single entity object (Mendix’s “First object” range). Otherwise the result is a list, including with LIMIT/OFFSET. A bare LIMIT 1 is a list of one (a script file without the header reads it differently; see Language Versions and Migration). describe prints the object range as FIRST.

RETRIEVE by Association

Retrieves objects by following an association from an existing object:

-- Retrieve related objects via association
RETRIEVE $Lines FROM $Order/Sales.OrderLine_Order;

-- Retrieve a single associated object
RETRIEVE $Customer FROM $Order/Sales.Order_Customer;

The association path uses the format $Variable/Module.AssociationName.

RETRIEVE from Variable List

Retrieves from an in-memory list variable:

RETRIEVE $Match FROM $CustomerList
  WHERE Email = $SearchEmail
  LIMIT 1;

Call Activities

CALL MICROFLOW

Calls another microflow, passing parameters and optionally receiving a return value:

-- Call with return value
$Total = CALL MICROFLOW Sales.SUB_CalculateTotal (
  OrderLines = $Lines
);

-- Call without return value
CALL MICROFLOW Sales.SUB_SendNotification (
  Customer = $Customer,
  Message = 'Order confirmed'
);

-- Call with no parameters
$Config = CALL MICROFLOW Admin.GetSystemConfig ();

CALL NANOFLOW

Calls a nanoflow from within a microflow:

$Result = CALL NANOFLOW MyModule.ValidateInput (
  InputValue = $Value
);

CALL JAVA ACTION

Calls a Java action:

$Hash = CALL JAVA ACTION MyModule.HashPassword (
  Password = $RawPassword
);

Java action parameters follow the same Name = value syntax.

UI Activities

SHOW PAGE

Opens a page, passing parameters:

SHOW PAGE Sales.Order_Edit (Order = $Order);

The parameter syntax is PageParam = $MicroflowVar, with no $ on the page’s parameter name. Multiple parameters are comma-separated:

SHOW PAGE Sales.OrderDetail (
  Order = $Order,
  Customer = $Customer
);

The older spellings ($Order = $Order) and (Order: $Order) still parse but are deprecated (MDL-DEPR006, MDL-DEPR007); mxcli fmt --upgrade rewrites them.

CLOSE PAGE

Closes the current page:

CLOSE PAGE;

Validation

VALIDATION FEEDBACK

Displays a validation error message on a specific attribute of an object:

VALIDATION FEEDBACK $Customer/Email MESSAGE 'Email address is required';
VALIDATION FEEDBACK $Order/TotalAmount MESSAGE 'Total must be greater than zero';

The syntax is VALIDATION FEEDBACK $Variable/AttributeName MESSAGE 'message text'.

Logging

LOG

Writes a message to the Mendix runtime log:

LOG INFO 'Order created successfully';
LOG WARNING 'Customer has no email address';
LOG ERROR 'Failed to process payment';

Log levels: INFO, WARNING, ERROR.

Optionally specify a log node name:

LOG INFO NODE 'OrderProcessing' 'Order created: ' + $Order/OrderNumber;
LOG ERROR NODE 'PaymentGateway' 'Payment failed for order ' + $Order/OrderNumber;

Email

SEND EMAIL

Sends mail over SMTP with the built-in Send Email activity (Studio Pro 11.13+, beta) — no Email Connector module needed. Microflows only.

SEND EMAIL (
  From: @Shop.MailSender,
  To: $Order/CustomerEmail,
  Cc: 'archive@example.com',
  Subject: 'Order {1} confirmed' WITH ({1} = $Order/OrderNumber),
  Body: TEMPLATE 'Hi {1}, your order ships soon.' WITH ({1} = $Order/CustomerName),
  HtmlBody: TEMPLATE '<p>Your order ships soon.</p>',
  Headers: ('X-Correlation-Id': 'order-confirmation'),
  Attachment: $Invoice,
  Host: @Shop.SmtpHost,
  Port: @Shop.SmtpPort,
  SecurityType: SSL,
  CheckServerIdentity: true,
  ConnectionTimeout: 30000,
  Authentication: BASIC (Username: @Shop.SmtpUser, Password: @Shop.SmtpPassword),
) ON ERROR WITHOUT ROLLBACK BEGIN
  LOG ERROR NODE 'Mail' 'Sending failed';
END ERROR;

The activity’s settings are one property list, as for CALL REST SERVICE (Activity Settings); the order of the keys does not matter. From, Host, Port and at least one of To, Cc and Bcc are required — mxbuild reports a missing one as CE0166.

• Addresses, host, port, user and password are expressions. All are String except Port, which is Integer or Long. Prefer constants for the connection settings, and never a literal password.
• Subject is a text template, as in LOG; Body and HtmlBody take template '…', as a REST body does. Placeholders {1}, {2} … are filled by String expressions in WITH. Any other expression is stored as the template '{1}'.
• Headers are plain strings: the name holds letters, digits and hyphens.
• Attachment is a System.FileDocument variable, a list of them, or a specialization.
• Defaults, which DESCRIBE leaves out: SecurityType: tls, ConnectionTimeout: 20000 (milliseconds), no CheckServerIdentity (it applies to SSL only), no authentication.

Studio Pro’s Test Email tab is an editor tool and is not part of MDL; rewriting the microflow stores it empty.

Database Query Execution

EXECUTE DATABASE QUERY

Executes a Database Connector query defined in the project:

-- Basic execution (3-part qualified name: Module.Connection.Query)
$Result = EXECUTE DATABASE QUERY MyModule.MyConn.GetCustomers;

-- Dynamic SQL query
$Result = EXECUTE DATABASE QUERY MyModule.MyConn.SearchQuery
  DYNAMIC 'SELECT * FROM customers WHERE name LIKE ?';

-- With parameters
$Result = EXECUTE DATABASE QUERY MyModule.MyConn.GetByEmail (EmailParam = $Email);

-- With runtime connection override
$Result = EXECUTE DATABASE QUERY MyModule.MyConn.GetData
  CONNECTION $RuntimeConnString;

The query name follows a three-part naming convention: Module.ConnectionName.QueryName.

Note: Error handling (ON ERROR) is not supported on EXECUTE DATABASE QUERY activities.

Summary Table