feat(examples): add validation example

README.md

@@ -167,6 +167,10 @@ const targetHandleWithValidation = (
 - `style`: css properties
 - `className`: additional class name
 
+### Validation
+
+The handle receives the additional class names `connecting` when the connection line is above the handle and `valid` if the connection is valid. You can find an example which uses these classes [here](/example/src/Validation/index.js).
+
 ### Multiple Handles
 
 If you need multiple source or target handles you can achieve this by creating a custom node. Normally you just use the id of a node for the `source` or `target` of an edge. If you have multiple source or target handles you need to pass an id to these handles. These ids get then added to the node id, so that you can connect a specific handle. If you have a node with an id = `1` and a handle with an id = `a` you can connect this handle by using the id = `1__a`.
@@ -345,6 +349,8 @@ The React Flow wrapper has the className `react-flow`. If you want to change the
   * `.top` is added when position = 'top'
   * `.left` is added when position = 'left'
   * `.right` is added when position = 'right'
+  * `.connecting` is added when connection line is above a handle
+  * `.valid` is added when connection line is above a handle and the connection is valid
 * `.react-flow__background` - Background component
 * `.react-flow__minimap` - Mini map component
 * `.react-flow__controls` - Controls component

example/src/Validation/index.js

@@ -0,0 +1,44 @@
+import React, { useState } from 'react';
+
+import ReactFlow, { addEdge, Handle } from 'react-flow-renderer';
+
+import './validation.css';
+
+const initialElements = [
+  { id: '0', type: 'custominput', position: { x: 0, y: 150 } },
+  { id: 'A', data: { label : 'A' }, position: { x: 250, y: 0 }, targetPosition: 'left', sourcePosition: 'right' },
+  { id: 'B', data: { label : 'B' }, position: { x: 250, y: 150 }, targetPosition: 'left', sourcePosition: 'right' },
+  { id: 'C', data: { label : 'C' }, position: { x: 250, y:300 }, targetPosition: 'left', sourcePosition: 'right' },
+];
+
+const CustomInput = () => (
+  <>
+    <div>Only connectable with B</div>
+    <Handle
+      type="source"
+      position="right"
+      style={{ background: '#e6e6e9' }}
+      isValidConnection={connection => connection.target === 'B'}
+    />
+  </>
+);
+
+const HorizontalFlow = () => {
+  const [elements, setElements] = useState(initialElements);
+  const onConnect = (params) => setElements(els => addEdge(params, els));
+
+  return (
+    <ReactFlow
+      elements={elements}
+      onConnect={onConnect}
+      selectNodesOnDrag={false}
+      onLoad={reactflowInstance => reactflowInstance.fitView()}
+      className="validationflow"
+      nodeTypes={{
+        custominput: CustomInput
+      }}
+    />
+  );
+}
+
+export default HorizontalFlow;

example/src/Validation/validation.css

@@ -0,0 +1,23 @@
+.validationflow .react-flow__node {
+  background: #e6e6e9;
+  border: 1px solid #ddd;
+}
+
+.validationflow .react-flow__node-custominput {
+  width: 150px;
+  border-radius: 5px;
+  padding: 10px;
+  background: #fff;
+  color: #555;
+  border: 1px solid #ddd;
+  text-align: center;
+  font-size: 12px;
+}
+
+.validationflow .connecting {
+  background: #ff6060;
+}
+
+.validationflow .connecting.valid {
+  background: #55dd99;
+}

example/src/index.css

@@ -141,6 +141,14 @@ nav a.active:before {
   color: #f8f8f8;
 }
 
+.react-flow__node-selectorNode {
+  font-size: 12px;
+  background: #eee;
+  border: 1px solid #555;
+  border-radius: 5px;
+  text-align: center;
+}
+
 @media screen and (min-width: 768px) {
   nav {
     position: relative;

example/src/index.js

@@ -9,6 +9,7 @@ import Stress from './Stress';
 import Inactive from './Inactive';
 import Empty from './Empty';
 import Edges from './Edges';
+import Validation from './Validation';
 import Horizontal from './Horizontal';
 
 import './index.css';
@@ -33,6 +34,10 @@ const routes = [{
   path: '/horizontal',
   component: Horizontal,
   label: 'Horizontal'
+}, {
+  path: '/validation',
+  component: Validation,
+  label: 'Validation'
 }, {
   path: '/stress',
   component: Stress,

src/style.css

@@ -102,13 +102,10 @@
 
 .react-flow__node {
   position: absolute;
-  color: #222;
-  text-align: center;
   user-select: none;
   pointer-events: all;
   transform-origin: 0 0;
   cursor: grab;
-  background: #eee;
 
   &.selected,
   &.selected:hover {
@@ -124,28 +121,28 @@
   }
 }
 
-.react-flow__node-default {
+.react-flow__node-default,
-  padding: 10px;
+.react-flow__node-input,
-  border-radius: 5px;
-  width: 150px;
-  background: #ff6060;
-  font-size: 12px;
-}
-
-.react-flow__node-input {
-  padding: 10px;
-  border-radius: 5px;
-  width: 150px;
-  background: #9999ff;
-  font-size: 12px;
-}
-
 .react-flow__node-output {
   padding: 10px;
   border-radius: 5px;
   width: 150px;
-  background: #55dd99;
   font-size: 12px;
+  color: #222;
+  text-align: center;
+}
+
+.react-flow__node-default {
+  background: #ff6060;
+}
+
+.react-flow__node-input {
+  background: #9999ff;
+}
+
+.react-flow__node-output {
+  background: #55dd99;
+
 }
 
 .react-flow__nodesselection {