Format reference

Expression placeholders

The inlined result must be a valid Mendix microflow/nanoflow boolean expression (Exclusive Split expression condition). TBT does not compile-check it beyond string substitution.

Empty values: generated flows run the expression as-is, also when the attribute is empty. Write $Value = empty or ... unless the rule should reject empty values (for example, a "not blank" rule).

Literal formatting when substituting `$ParamName`:

Message placeholders

`serverOnly`

• `false` (default): available to both Validate… (microflow) and DTO… attribute nanoflow paths.
• `true`: still included on the Validate… microflow preset list (includeServerOnly: true). On the DTO nano path, expressions with serverOnly: true are excluded (includeServerOnly: false). Tracked as skipped document ids for nano copy.

`appliesTo` matching

A preset is offered for an attribute when appliesTo contains the attribute’s type, or the attribute is HashedString and appliesTo contains String.

`defaultForAttributes` auto-select

When Validate/DTO adds an attribute that has no rules yet, TBT looks for expression presets whose defaultForAttributes contains the attribute name (case-insensitive exact). If several match, the one with the smallest label via localeCompare wins.

Example A — simple (no params)

Editor

Stored JSON

{
  "schemaVersion": 1,
  "label": "Not blank",
  "documentation": "Trimmed string must not be empty",
  "appliesTo": ["String"],
  "serverOnly": false,
  "defaultForAttributes": [],
  "params": [],
  "expression": "trim($Value) != ''",
  "message": "{AttributeName} must not be blank"
}

For attribute Name on entity Person, generate inlines to trim($Person/Name) != '' and message Name must not be blank.

Example B — realistic with params + operators

Editor

Stored JSON

{
  "schemaVersion": 1,
  "label": "Range",
  "documentation": "Inclusive/exclusive bounds via operators",
  "appliesTo": ["Integer", "Long", "Decimal"],
  "serverOnly": false,
  "defaultForAttributes": ["Age"],
  "params": [
    {
      "name": "Lower",
      "type": "Integer",
      "required": true,
      "default": 0,
      "operator": { "options": [">=", ">"], "default": ">=" }
    },
    {
      "name": "Upper",
      "type": "Integer",
      "required": true,
      "default": 100,
      "operator": { "options": ["<=", "<"], "default": "<=" }
    }
  ],
  "expression": "$Value = empty or ($Value {Lower.operator} $Lower and $Value {Upper.operator} $Upper)",
  "message": "{AttributeName} must be between {Lower} and {Upper}"
}

With usage Lower=18/>=, Upper=65/<= on $Order/Age → $Order/Age = empty or ($Order/Age >= 18 and $Order/Age <= 65), message Age must be between 18 and 65.

Example C — server-only

Same as Example A but Server-only checked → "serverOnly": true. Offered in Validate…; omitted from DTO… nanoflow expression presets.

`name`

Emitted as the attribute name on the target entity. Same string is the catalog override key.

`type` / `length` / `defaultValue`

• length applied only when type is String (0 = unlimited in Mendix).
• defaultValue written onto DomainModels$StoredValue.defaultValue as the string you entered (Boolean examples in the seed use "true"; Decimal uses "0").

`required`

When true (and not calculated), after creating the attribute TBT best-effort adds a Required validation rule (DomainModels$RequiredRuleInfo) with error text:

{AttributeName} is required.

If a Required rule for that attribute already exists, it is left alone. Failures are logged; attribute emit still succeeds.

`calculated`

When true:

1. Ensures microflow CAL_{entity}_{attribute} under folder Model/{entity}/Private (folder/name templates are settings-overridable; pattern id cal).
2. Stub End return: '' / false / empty / 0 by type (Long return type becomes Integer in the Microflow API).
3. Attribute value = CalculatedValue with that microflow, passEntity: true.
4. If pattern cal is disabled in Settings → emit error: Calculated attributes are disabled in Settings (pattern cal).
5. Existing microflow with that name → reuse (no recreate).

Tags / aliases / `defaultForEntities`

• Picker search scores name (exact 100, prefix 80, contains 60), then aliases (55/45), then tags (30).
• If the target entity name matches defaultForEntities (case-insensitive exact), score gets +15 (softBoost). Presets are never hidden solely because the entity does not match.

Example A — simple Boolean

Editor: Name Active; Type Boolean; Default value true; Tags status; Aliases IsActive, Enabled.

{
  "schemaVersion": 1,
  "name": "Active",
  "type": "Boolean",
  "defaultValue": "true",
  "tags": ["status"],
  "defaultForEntities": [],
  "aliases": ["IsActive", "Enabled"]
}

Example B — realistic String (seeded Email)

Editor: Name Email; Type String; Length 254; Required unchecked; Tags contact; Default for entity names Person, Customer, User, Contact; Aliases EmailAddress.

{
  "schemaVersion": 1,
  "name": "Email",
  "type": "String",
  "length": 254,
  "required": false,
  "tags": ["contact"],
  "defaultForEntities": ["Person", "Customer", "User", "Contact"],
  "aliases": ["EmailAddress"]
}

Example C — calculated

Editor: Name Total; Type Decimal; Calculated checked (Default value / Required hidden).

{
  "schemaVersion": 1,
  "name": "Total",
  "type": "Decimal",
  "calculated": true,
  "tags": [],
  "defaultForEntities": [],
  "aliases": []
}

On entity Order this creates attribute Total (calculated) and microflow Order.CAL_Order_Total under Model/Order/Private (stub returning 0), unless pattern cal is disabled.