feat: add Import Mapping, Export Mapping, and SEND REST REQUEST support

Clean rework of PR #84 (call-rest branch): drops duplicate JSON Structure
code already on main, removes formatting noise (~30 files), and changes
mapping syntax from -> to AS for consistency with existing database
client mappings and design guidelines.

New features:
- CREATE/DROP/SHOW/DESCRIBE IMPORT MAPPING with AS syntax
- CREATE/DROP/SHOW/DESCRIBE EXPORT MAPPING with AS syntax
- SEND REST REQUEST microflow activity
- Lint rule mpr008_overlapping_activities
- Import/export mapping examples in REST client doctype tests
- Skill doc for end-to-end REST call from JSON workflow

Co-Authored-By: Dennis Kho <dennis.kho@mendix.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 3 people

.claude/skills/mendix/README.md

@@ -41,7 +41,8 @@ External system integration:
 |-------|---------|----------|
 | [database-connections.md](database-connections.md) | Mendix Database Connector | Connecting to Oracle, PostgreSQL, etc. via JDBC |
 | [demo-data.md](demo-data.md) | Demo data & IMPORT | Seeding data, `IMPORT FROM` bulk import from external DB |
-| [rest-client.md](rest-client.md) | REST API consumption | Calling external REST APIs |
+| [rest-client.md](rest-client.md) | REST API consumption | Calling external REST APIs via consumed REST client documents |
+| [rest-call-from-json.md](rest-call-from-json.md) | REST CALL end-to-end | JSON Structure → Entities → Import Mapping → REST CALL microflow |
 | [java-actions.md](java-actions.md) | Custom Java actions | Extending with Java code |
 
 ## Page Patterns
@@ -79,6 +80,8 @@ Load skills based on the task:
 | "Process list of items" | `patterns-data-processing.md` |
 | "Fix MDL error" | `cheatsheet-errors.md` |
 | "Import data from database" | `demo-data.md` |
+| "Call a REST API / integrate JSON endpoint" | `rest-call-from-json.md` |
+| "Create JSON structure / import mapping" | `rest-call-from-json.md` |
 | "Seed/populate test data" | `demo-data.md` |
 | "Update widget properties" | `bulk-widget-updates.md` |
 | "Change widgets in bulk" | `bulk-widget-updates.md` |

.claude/skills/mendix/rest-call-from-json.md

@@ -0,0 +1,232 @@
+# REST Call from JSON Payload — End-to-End Skill
+
+Use this skill to generate the full stack of Mendix integration artifacts from a JSON payload:
+JSON Structure → Non-persistent entities → Import Mapping → REST CALL microflow.
+
+## Overview — Four Steps
+
+1. **CREATE JSON STRUCTURE** — store the raw payload and derive the element tree
+2. **CREATE ENTITY** (non-persistent) — one per JSON object type, with attributes per JSON field
+3. **CREATE IMPORT MAPPING** — link JSON structure elements to entities and attributes
+4. **CREATE MICROFLOW** — inline REST CALL that invokes the import mapping
+
+---
+
+## Step 1 — JSON Structure
+
+```sql
+CREATE JSON STRUCTURE Module.JSON_MyStructure
+  SNIPPET '{"key": "value", "count": 1}';
+```
+
+- The executor **formats** the snippet (pretty-print) then **refreshes** (derives element tree) automatically.
+- The snippet must be valid JSON; use single quotes around it in MDL.
+- Escape single quotes inside the snippet by doubling them: `''`.
+- The derived element tree must stay consistent with the snippet — the executor sorts JSON object keys alphabetically to match `json.MarshalIndent` output.
+
+**Verify** after creation:
+```sql
+DESCRIBE JSON STRUCTURE Module.JSON_MyStructure;
+-- Should show: element tree under "-- Element tree:" comment
+```
+
+---
+
+## Step 2 — Non-Persistent Entities
+
+Derive one entity per JSON object type. Name them after what they represent (not after JSON keys).
+
+```sql
+CREATE ENTITY Module.MyRootObject (NON_PERSISTENT)
+  stringField   : String
+  intField      : Integer
+  decimalField  : Decimal
+  boolField     : Boolean DEFAULT false;
+
+CREATE ENTITY Module.MyNestedObject (NON_PERSISTENT)
+  name : String
+  code : String;
+
+CREATE ASSOCIATION Module.MyRootObject_MyNestedObject
+  FROM Module.MyRootObject
+  TO Module.MyNestedObject;
+```
+
+**Rules:**
+- All string fields: bare `String` (no length — unlimited)
+- All number fields: `Integer`, `Decimal`, or `Long` — remove defaults for optional fields
+- Boolean fields **require** `DEFAULT true|false`
+- `NON_PERSISTENT` — these entities are not stored in the database
+- One association per parent→child relationship; name it `Parent_Child`
+
+---
+
+## Step 3 — Import Mapping
+
+```sql
+CREATE IMPORT MAPPING Module.IMM_MyMapping
+  FROM JSON STRUCTURE Module.JSON_MyStructure
+{
+  "" AS Module.MyRootObject (Create) {
+    nestedKey AS Module.MyNestedObject (Create) VIA Module.MyRootObject_MyNestedObject {
+      name AS name (String)
+      code AS code (String)
+    }
+    stringField AS stringField (String)
+    intField    AS intField    (Integer)
+  }
+};
+```
+
+**Syntax rules:**
+- Root element uses `""` (empty string) as the JSON key — it maps the top-level object
+- Object mappings: `jsonKey AS Module.Entity (Create|Find|FindOrCreate)`
+- Value mappings: `jsonKey AS attributeName (String|Integer|Long|Decimal|Boolean|DateTime)`
+- `VIA Module.Association` — required when mapping a nested object reachable via an association
+- No semicolons between child elements inside `{}`
+
+**Verify** after creation — check Schema elements are ticked in Studio Pro:
+- Open the import mapping in Studio Pro
+- All JSON structure elements should appear ticked in the Schema elements panel
+- If not ticked: JsonPath mismatch between import mapping and JSON structure elements
+
+---
+
+## Step 4 — REST CALL Microflow
+
+Place the microflow in the `[Pages]/Operations/` folder or `Private/` depending on whether it is public.
+
+```sql
+CREATE MICROFLOW Module.GET_MyData ()
+BEGIN
+  @position(-5, 200)
+  DECLARE $baseUrl String = 'https://api.example.com';
+  @position(185, 200)
+  DECLARE $endpoint String = $baseUrl + '/path';
+  @position(375, 200)
+  $Result = REST CALL GET '{1}' WITH ({1} = $endpoint)
+    HEADER 'Accept' = 'application/json'
+    TIMEOUT 300
+    RETURNS MAPPING Module.IMM_MyMapping AS Module.MyRootObject ON ERROR ROLLBACK;
+  @position(565, 200)
+  LOG INFO NODE 'Integration' 'Retrieved result' WITH ();
+END;
+/
+```
+
+**Key points:**
+- `@position` annotations control the canvas layout — StartEvent is auto-placed 150px to the left of the first annotated activity
+- The output variable name is **automatically derived** from the entity name in `AS Module.MyEntity` — do NOT hardcode it on the left side; the executor overrides it
+- Single vs list result is **automatically detected**: if the JSON structure's root element is an Object, the variable type is `ObjectType` (single); if Array, `ListType` (list)
+- `ON ERROR ROLLBACK` — standard error handling for integration calls
+
+**For list responses** (JSON root is an array):
+```sql
+  $Results = REST CALL GET '{1}' WITH ({1} = $endpoint)
+    HEADER 'Accept' = 'application/json'
+    TIMEOUT 300
+    RETURNS MAPPING Module.IMM_MyMapping AS Module.MyItem ON ERROR ROLLBACK;
+  @position(565, 200)
+  $Count = COUNT($MyItem);
+```
+
+---
+
+## Complete Example — Bible Verse API
+
+```sql
+-- Step 1: JSON Structure
+CREATE JSON STRUCTURE Integrations.JSON_BibleVerse
+  SNIPPET '{"translation":{"identifier":"web","name":"World English Bible","language":"English","language_code":"eng","license":"Public Domain"},"random_verse":{"book_id":"1SA","book":"1 Samuel","chapter":17,"verse":49,"text":"David put his hand in his bag, took a stone, and slung it."}}';
+
+-- Step 2: Entities
+CREATE ENTITY Integrations.BibleApiResponse (NON_PERSISTENT);
+
+CREATE ENTITY Integrations.BibleTranslation (NON_PERSISTENT)
+  identifier    : String
+  name          : String
+  language      : String
+  language_code : String
+  license       : String;
+
+CREATE ENTITY Integrations.BibleVerse (NON_PERSISTENT)
+  book_id : String
+  book    : String
+  chapter : Integer
+  verse   : Integer
+  text    : String;
+
+CREATE ASSOCIATION Integrations.BibleApiResponse_BibleTranslation
+  FROM Integrations.BibleApiResponse
+  TO Integrations.BibleTranslation;
+
+CREATE ASSOCIATION Integrations.BibleApiResponse_BibleVerse
+  FROM Integrations.BibleApiResponse
+  TO Integrations.BibleVerse;
+
+-- Step 3: Import Mapping
+CREATE IMPORT MAPPING Integrations.IMM_BibleVerse
+  FROM JSON STRUCTURE Integrations.JSON_BibleVerse
+{
+  "" AS Integrations.BibleApiResponse (Create) {
+    translation AS Integrations.BibleTranslation (Create) VIA Integrations.BibleApiResponse_BibleTranslation {
+      identifier    AS identifier    (String)
+      language      AS language      (String)
+      language_code AS language_code (String)
+      license       AS license       (String)
+      name          AS name          (String)
+    }
+    random_verse AS Integrations.BibleVerse (Create) VIA Integrations.BibleApiResponse_BibleVerse {
+      book    AS book    (String)
+      book_id AS book_id (String)
+      chapter AS chapter (Integer)
+      text    AS text    (String)
+      verse   AS verse   (Integer)
+    }
+  }
+};
+
+-- Step 4: Microflow
+CREATE MICROFLOW Integrations.GET_BibleVerse_Random ()
+BEGIN
+  @position(-5, 200)
+  DECLARE $baseUrl String = 'https://bible-api.com';
+  @position(185, 200)
+  DECLARE $endpoint String = $baseUrl + '/data/web/random';
+  @position(375, 200)
+  $Result = REST CALL GET '{1}' WITH ({1} = $endpoint)
+    HEADER 'Accept' = 'application/json'
+    TIMEOUT 300
+    RETURNS MAPPING Integrations.IMM_BibleVerse AS Integrations.BibleApiResponse ON ERROR ROLLBACK;
+  @position(565, 200)
+  LOG INFO NODE 'Integration' 'Retrieved Bible verse' WITH ();
+END;
+/
+```
+
+---
+
+## Gotchas and Common Errors
+
+| Symptom | Cause | Fix |
+|---------|-------|-----|
+| Studio Pro "not consistent with snippet" | JSON element tree keys not in alphabetical order | Executor sorts keys; re-derive from snippet |
+| Schema elements not ticked in import mapping | JsonPath mismatch | Named object elements use `(Object)\|key`, NOT `(Object)\|key\|(Object)` |
+| Import mapping not linked in REST call | Wrong BSON field name | Use `ReturnValueMapping`, not `Mapping` |
+| Studio Pro shows "List of X" but mapping returns single X | `ForceSingleOccurrence` not set | Executor auto-detects from JSON structure root element type |
+| StartEvent behind first activities | Default posX=200 vs @position(-5,...) | Fixed: executor pre-scans for first @position and shifts StartEvent left |
+| `TypeCacheUnknownTypeException` | Wrong BSON `$Type` names | `ImportMappings$ObjectMappingElement` / `ImportMappings$ValueMappingElement` (no `Import` prefix) |
+| Attribute not found in Studio Pro | Attribute not fully qualified | Must be `Module.Entity.AttributeName` in the BSON |
+
+---
+
+## Naming Conventions (MES)
+
+| Artifact | Pattern | Example |
+|----------|---------|---------|
+| JSON Structure | `JSON_<ApiName>` | `JSON_BibleVerse` |
+| Import Mapping | `IMM_<ApiName>` | `IMM_BibleVerse` |
+| Root entity | Describes the API response | `BibleApiResponse` |
+| Nested entities | Describes the domain concept | `BibleVerse`, `BibleTranslation` |
+| Microflow | `METHOD_Resource_Operation` | `GET_BibleVerse_Random` |
+| Folder | `Private/` for mappings/structures, `Operations/` for public microflows | — |

cmd/mxcli/cmd_lint.go

@@ -141,6 +141,9 @@ Examples:
 		lint.AddRule(rules.NewWeakPasswordPolicyRule())
 		lint.AddRule(rules.NewDemoUsersActiveRule())
 
+		// MPR008 - requires BSON inspection
+		lint.AddRule(rules.NewOverlappingActivitiesRule())
+
 		// Convention rules (CONV011-CONV014) - require BSON inspection
 		lint.AddRule(rules.NewNoCommitInLoopRule())
 		lint.AddRule(rules.NewExclusiveSplitCaptionRule())

cmd/mxcli/cmd_report.go

@@ -101,6 +101,9 @@ Examples:
 		lint.AddRule(rules.NewWeakPasswordPolicyRule())
 		lint.AddRule(rules.NewDemoUsersActiveRule())
 
+		// MPR008 - requires BSON inspection
+		lint.AddRule(rules.NewOverlappingActivitiesRule())
+
 		// Convention rules (CONV011-CONV014)
 		lint.AddRule(rules.NewNoCommitInLoopRule())
 		lint.AddRule(rules.NewExclusiveSplitCaptionRule())