feat(import): forgive missing bpmnPlane#bpmnElement

Related to #146

lib/import/BpmnTreeWalker.js

@@ -6,6 +6,20 @@ var Refs = require('object-refs');
 
 var diRefs = new Refs({ name: 'bpmnElement', enumerable: true }, { name: 'di' });
 
+function elementToString(e) {
+  return '<' + e.$type + (e.id ? ' id="' + e.id : '') + '" />';
+}
+
+/**
+ * Find a suitable display candidate for definitions where the DI does not
+ * correctly specify one.
+ */
+function findDisplayCandidate(definitions) {
+  return _.find(definitions.rootElements, function(e) {
+    return e.$instanceOf('bpmn:Process') || e.$instanceOf('bpmn:Collaboration');
+  });
+}
+
 
 function BpmnTreeWalker(handler) {
 
@@ -34,7 +48,7 @@ function BpmnTreeWalker(handler) {
 
     // avoid multiple rendering of elements
     if (gfx) {
-      throw new Error('already rendered <' + element.id + '>');
+      throw new Error('already rendered ' + elementToString(element));
     }
 
     // call handler
@@ -68,7 +82,7 @@ function BpmnTreeWalker(handler) {
       diRefs.bind(bpmnElement, 'di');
       bpmnElement.di = di;
     } else {
-      logError('no bpmnElement for <' + di.$type + '#' + di.id + '>', { element: di });
+      logError('no bpmnElement referenced in ' + elementToString(di), { element: di });
     }
   }
 
@@ -110,11 +124,31 @@ function BpmnTreeWalker(handler) {
     // load DI from selected diagram only
     handleDiagram(diagram);
 
-    var plane = diagram.plane,
+
-        rootElement = plane.bpmnElement;
+    var plane = diagram.plane;
+
+    if (!plane) {
+      throw new Error('no plane for ' + elementToString(diagram));
+    }
+
+
+    var rootElement = plane.bpmnElement;
+
+    // ensure we default to a suitable display candidate (process or collaboration),
+    // even if non is specified in DI
+    if (!rootElement) {
+      rootElement = findDisplayCandidate(definitions);
 
       if (!rootElement) {
-      throw new Error('no rootElement referenced in BPMNPlane <' + diagram.plane.id + '>');
+        throw new Error('do not know what to display');
+      } else {
+
+        logError('correcting missing bpmnElement on ' + elementToString(plane) + ' to ' + elementToString(rootElement));
+
+        // correct DI on the fly
+        plane.bpmnElement = rootElement;
+        registerDi(plane);
+      }
     }
 
 
@@ -128,7 +162,7 @@ function BpmnTreeWalker(handler) {
       // force drawing of everything not yet drawn that is part of the target DI
       handleUnhandledProcesses(definitions.rootElements, ctx);
     } else {
-      throw new Error('unsupported root element for bpmndi:Diagram <' + rootElement.$type + '>');
+      throw new Error('unsupported bpmnElement for ' + elementToString(plane) + ' : ' + elementToString(rootElement));
     }
 
     // handle all deferred elements
@@ -166,10 +200,8 @@ function BpmnTreeWalker(handler) {
   }
 
   function handleMessageFlows(messageFlows, context) {
-    if (messageFlows) {
     _.forEach(messageFlows, contextual(handleMessageFlow, context));
   }
-  }
 
   function handleDataAssociation(association, context) {
     visitIfDi(association, context);
@@ -313,7 +345,8 @@ function BpmnTreeWalker(handler) {
         handleDataElement(e, context);
       } else {
         logError(
-          'unrecognized flowElement <' + e.$type + '> in context ' + (context ? context.id : null),
+          'unrecognized flowElement ' + elementToString(e) + ' in context ' +
+          (context ? elementToString(context) : null),
           { element: e, context: context });
       }
     });

test/spec/ViewerSpec.js

@@ -26,8 +26,8 @@ describe('viewer', function() {
   function createViewer(xml, done) {
     var viewer = new Viewer({ container: container });
 
-    viewer.importXML(xml, function(err) {
+    viewer.importXML(xml, function(err, warnings) {
-      done(err, viewer);
+      done(err, warnings, viewer);
     });
   }
 
@@ -93,7 +93,7 @@ describe('viewer', function() {
 
       var xml = fs.readFileSync('test/fixtures/bpmn/simple.bpmn', 'utf8');
 
-      createViewer(xml, function(err, viewer) {
+      createViewer(xml, function(err, warnings, viewer) {
 
         // when
         var overlays = viewer.get('overlays'),
@@ -145,9 +145,13 @@ describe('viewer', function() {
 
       var xml = fs.readFileSync('test/fixtures/bpmn/error/di-plane-no-bpmn-element.bpmn', 'utf8');
 
-      createViewer(xml, function(err) {
+      createViewer(xml, function(err, warnings) {
-        expect(err).toBeDefined();
+
-        expect(err.message).toEqual('no rootElement referenced in BPMNPlane <BPMNPlane_1>');
+        expect(err).not.toBeDefined();
+        expect(warnings.length).toBe(2);
+
+        expect(warnings[0].message).toEqual('no bpmnElement referenced in <bpmndi:BPMNPlane id="BPMNPlane_1" />');
+        expect(warnings[1].message).toEqual('correcting missing bpmnElement on <bpmndi:BPMNPlane id="BPMNPlane_1" /> to <bpmn:Process id="Process_1" />');
 
         done();
       });
@@ -179,7 +183,7 @@ describe('viewer', function() {
 
       var xml = fs.readFileSync('test/fixtures/bpmn/simple.bpmn', 'utf8');
 
-      createViewer(xml, function(err, viewer) {
+      createViewer(xml, function(err, warnings, viewer) {
 
         expect(viewer.get('bpmnjs')).toBe(viewer);
 
@@ -220,7 +224,7 @@ describe('viewer', function() {
       // given
       var xml = fs.readFileSync('test/fixtures/bpmn/empty-definitions.bpmn', 'utf8');
 
-      createViewer(xml, function(err, viewer) {
+      createViewer(xml, function(err, warnings, viewer) {
 
         if (err) {
           return done(err);
@@ -247,7 +251,7 @@ describe('viewer', function() {
       // given
       var xml = fs.readFileSync('test/fixtures/bpmn/complex.bpmn', 'utf8');
 
-      createViewer(xml, function(err, viewer) {
+      createViewer(xml, function(err, warnings, viewer) {
 
         if (err) {
           return done(err);
@@ -287,7 +291,7 @@ describe('viewer', function() {
         svgDoc.appendChild(rect);
       }
 
-      createViewer(xml, function(err, viewer) {
+      createViewer(xml, function(err, warnings, viewer) {
 
         if (err) {
           return done(err);