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How to get the flow of the connections

14 Oct 2021 / 6 minutes to read

You can get the connectors inward entry and the outward entry through the inEdges and the outEdges properties.

Step1

The inEdges holds the collection of incoming connector/edges of the node. To get the inEdges collection, use the following code snippet.

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// gets the incoming connectors of the selected node
let diagram = this.$refs.diagram.ej2Instances;
let connectors = (diagram.selectedItems.connectors[0]).inEdges;

Step2

The outEdges holds the collection of outgoing connector/edges of the node. To get the OutEdges collection,use the following code snippet.

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//gets the out going connectors of the selected node
let diagram = this.$refs.diagram.ej2Instances;
let connectors = (diagram.selectedItems.connectors[0]).outEdges;

Step3

To get the collection of inEdges and outEdges of the nodes, you need to perform iteration as shown as follows. In the following code snippet, the collection of inEdges and outEdges of the selected nodes can be iterated.

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    let diagram = this.$refs.diagram.ej2Instances;
    // Consider the below flow chart
    if (diagram.selectedItems.nodes.length) {
            // Finds the connectors with in-ward communication
            // Initialy if we select the Design node it will retrieve the connector between the design node and the start node
            let connectors = (diagram.selectedItems.connectors[0]).inEdges;
            for (let i = 0; i < connectors.length; i++) {
                // Retrieves the inward linked node's connectors with the particular node.
                //if we select the Design node it will retrieve the connectors between the Start and the design node. And connectors in between the Design and Design error node.
                let index = diagram.connectors.indexOf(diagram.nameTable[connectors[i]]);
                // Retrieves the nodes id connected with the  particular node based on the  connector's source
                // If we select the start node it will retrieve the Design node.
                 let nodeId = diagram.nameTable[connectors[i]].sourceID;
            }
    }

Like inEdges iterating the need to iterate outEdges collections for the selected node.

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  let diagram = this.$refs.diagram.ej2Instances;
    // Consider the below flow chart
    if (diagram.selectedItems.nodes.length) {
            // Finds the connectors with out-ward communication
            let connectors = (diagram.selectedItems.connectors[0]).outEdges;
            for (let i = 0; i < connectors.length; i++) {
                // Retrieves the connectors with outward communication with the selected node
                // Initially if we select the start node ot will retrieve the connectors between start node and the design node
                let index = diagram.connectors.indexOf(diagram.nameTable[connectors[i]]);
                // Retrieves the nodes id connected with the  particular node based on the  connector's target
                // If select the Design node it will retrieve the Coding node
                let nodeId = diagram.nameTable[connectors[i]].targetID;
            }
    }

In the following sample, the flow of connections is described by various stages from top to bottom.

Source
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app.vue
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<template>
    <div id="app">
        <ejs-diagram style="display:block" ref="diagramObj" id="diagram" :width="width" :height="height" :nodes="nodes" :connectors="connectors" :selectionChange="selectionChange"></ejs-diagram>
    </div>
</template>

<script>
import Vue from "vue";
import {DiagramPlugin, NodeConstraints} from "@syncfusion/ej2-vue-diagrams";
Vue.use(DiagramPlugin);
let diagram;
let nodes = [];
let port1 = { id: "port1", offset: { x: 0.5, y: 1 } };
let port = { id: "port", offset: { x: 1, y: 0.5 } };
nodes.push(createNode("node1", 80, 50, "Terminator", "Begin", 100, 35));
nodes.push(
  createNode("node2", 250, 50, "Process", "Specify Collection", 120, 25, [port])
);
nodes.push(
  createNode("node3", 450, 50, "Decision", "Details Required?", 100, 50, [
    port1
  ])
);
nodes.push(createNode("node4", 600, 50, "Process", "Specify Details", 90, 25));
nodes.push(
  createNode("node5", 450, 150, "Process", "Design Collection", 100, 25, [port])
);
nodes.push(
  createNode("node6", 450, 250, "Process", "Cluster of events", 100, 25)
);
nodes.push(
  createNode("node7", 450, 350, "Process", "Record and analyze Results", 100, 25)
);
nodes.push(
  createNode("node8", 600, 250, "Process", "comply Transaction", 100, 25, [
    port
  ])
);
nodes.push(createNode("node9", 600, 350, "Terminator", "End", 100, 35));
nodes.push(createNode("node10", 350,10, "Text", "Select a node to find the inEdges of the selected node",300,35));

let connectors = [];
connectors.push(createConnector("connector1", "node1", "node2", ""));
connectors.push(createConnector("connector2", "node2", "node3", ""));
connectors.push(createConnector("connector3", "node3", "node4", "Yes"));
connectors.push(createConnector("connector4", "node3", "node5", "No"));
connectors.push(createConnector("connector5", "node5", "node6", ""));
connectors.push(createConnector("connector6", "node6", "node7", ""));
connectors.push(createConnector("connector7", "node8", "node6", ""));
connectors.push(createConnector("connector8", "node7", "node9", ""));
connectors.push(
  createConnector("connector10", "node4", "node5", "", "", "", "port",  220 ));

function createNode(name, offsetX, offsetY, shape, content, width, height, ports) {
  // update node properties
  let node = {};
  node.id = name;
  node.offsetX = offsetX;
  if(width){
    node.width = width
  }
  else
  node.height = 50;
  if(height){
    node.height = height;
  }
  else
  node.width = 150;
  node.offsetY = offsetY;
  let annotation = {};
  annotation.content = content;
  node.annotations = [annotation];
  node.shape = { type: "Flow", shape: shape };
  node.style = { fill: "#FBF6E1", strokeColor: "#E6C979", strokeWidth: 2 };
  if (ports) {
    node.ports = ports;
  }
  if(node.id === "node10"){
    node.constraints = NodeConstraints.Default & ~NodeConstraints.Select;
    node.shape= { type: "Text" };
  }

  return node;
}

function createConnector(name, source, target, content, type, direction, targetPort, length) {
  // update connector properties
  let connector = {};
  connector.id = name;
  connector.sourceID = source;
  connector.targetID = target;
  connector.style = { strokeWidth: 2 };
  let annotation = {};
  annotation.content = content;
  annotation.style = { fill: "white" };
  connector.annotations = [annotation];
  if (targetPort) {
    connector.targetPortId = targetPort;
  }
  let segment = {};
  if (type) {
    connector.type = type;
    segment.direction = direction;
    segment.type = type;
    segment.length = length;
    connector.segments = [segment];
  }
  return connector;
}

let highLightedObjects = [];
function NodeReachable() {
  diagram = diagram = this.$refs.diagramObj.ej2Instances;
  if (diagram.selectedItems.nodes.length) {
    let connectors = diagram.selectedItems.nodes[0].outEdges;
    let nodeList = foundNode(connectors, []);
    for (let i = 0; i < nodeList.length; i++) {
      let ind = diagram.connectors.indexOf(diagram.nameTable[nodeList[i]]);
      highLightedObjects.push(nodeList[i]);
      diagram.connectors[ind].style.strokeColor = "red";
      diagram.connectors[ind].targetDecorator.style.strokeColor = "red";
      diagram.connectors[ind].targetDecorator.style.fill = "red";
      diagram.dataBind();
    }
  }
}

function foundNode(list, nodeList) {
  diagram = diagram = this.$refs.diagramObj.ej2Instances;
  for (let i = 0; i < list.length; i++) {
    let connector = diagram.nameTable[list[i]];
    if (nodeList.indexOf(connector.id) > -1) {
      break;
    }
    if (
      !connector.annotations[0] ||
      (connector.annotations[0] && connector.annotations[0].content !== "No")
    ) {
      nodeList.push(connector.id);
    }
    if (diagram.nameTable[connector.targetID].outEdges.length) {
      if (list.indexOf(connector.targetID) === -1) {
        foundNode(diagram.nameTable[connector.targetID].outEdges, nodeList);
      }
    }
  }
  return nodeList;
}

function Unhighlight() {
  let obj = document.getElementById("diagram");
  diagram = obj.ej2_instances[0];
  for (let i = highLightedObjects.length - 1; i >= 0; i--) {
    if (diagram.nameTable[highLightedObjects[i]]) {
      let ind = diagram.nodes.indexOf(
        diagram.nameTable[highLightedObjects[i]]
      );
      diagram.nodes[ind].style.strokeColor = "#E6C979";
      diagram.dataBind();
    } else {
      let ind = diagram.connectors.indexOf(
        diagram.nameTable[highLightedObjects[i]]
      );
      diagram.connectors[ind].style.strokeColor = "black";
      diagram.connectors[ind].targetDecorator.style.strokeColor = "black";
      diagram.connectors[ind].targetDecorator.style.fill = "black";
      diagram.dataBind();
    }
  }
  highLightedObjects = [];
}

function selectionChange(arg) {
  NodeReachable();
  if (arg.state == "Changing") {
    Unhighlight();
    NodeReachable();
  }
}


export default {
    name: 'app',
  data() {
    return {
      width: "100%",
      height: "645px",
      nodes: nodes,
      connectors: connectors,
      selectionChange: selectionChange,
    }
  },
}



</script>
<style>
    @import "../../node_modules/@syncfusion/ej2-vue-diagrams/styles/material.css";
</style>
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