Question

我有这个场景我试图将一个JSON定义映射到另一个，我有一个名为 find 的递归函数，当我进行简单的操作但是当我发送复杂的条件时，它非常有效总是在分配上获得未定义值。

  var mapToModel = function(res){
  var processes = res.definitions.process;
  var diagrams = res.definitions.BPMNDiagram; 
  var documents = [];
  for(var prop in processes) {
    if(processes.hasOwnProperty(prop)){
      var propertyNames = Object.getOwnPropertyNames(processes[prop]);
      for(var property in processes[prop]){
        var mapping ={};
        if(property==="$"){
          //do something with the process
        }else{
        //shapes
          console.log("\n");
          mapping.id = new mongo.ObjectID();
          mapping.hash = hash.hashCode(new Date().toString());
          mapping.type = property;
          mapping.value = processes[prop][property];
          var bpmnItem = find(processes[prop][property], function(x) {return x;});
          var bpmnId = bpmnItem.$.id;
          console.log("bpmnId: "+bpmnId);
            if(bpmnId!=undefined){
              var returnVal =  find(diagrams,function(x){
                if(x.bpmnElement===bpmnId){
                  console.log("element found: " + JSON.stringify(x,null,4));
                  return x;
                }
              });
              console.log("returned value: "+returnVal);
          }
          documents.push(mapping);
        }
      }
    }
     return documents;
  }
}



function find(items,f) {
    for(var key in items) { 
        var elem = items[key]; 
        if (f(elem)) { console.log(JSON.stringify(elem,null,4)); return elem;}
        if(typeof elem === "object") { 
            find(elem,f); // call recursively
        }
    }
}

修改

控制台输出如下：

bpmnId: StartEvent_1
element found: {
    "id": "BPMNShape_1",
    "bpmnElement": "StartEvent_1"
}
returned value: undefined


bpmnId: SequenceFlow_9
element found: {
    "id": "BPMNEdge_SequenceFlow_10",
    "bpmnElement": "SequenceFlow_9",
    "sourceElement": "BPMNShape_1",
    "targetElement": "BPMNShape_Task_3"
}
returned value: undefined

等等...

输入数据的例子

"BPMNDiagram": [
            {
                "$": {
                    "id": "BPMNDiagram_1",
                    "name": "procurement subprocess"
                },
                "BPMNPlane": [
                    {
                        "$": {
                            "id": "BPMNPlane_1",
                            "bpmnElement": "process"
                        },
                        "BPMNShape": [
                            {
                                "$": {
                                    "id": "BPMNShape_1",
                                    "bpmnElement": "StartEvent_1"
                                },
                                "Bounds": [
                                    {
                                        "$": {
                                            "height": "36.0",
                                            "width": "36.0",
                                            "x": "20.0",
                                            "y": "182.0"
                                        }
                                    }
                                ]
                            },
                            {
                                "$": {
                                    "id": "BPMNShape_Task_3",
                                    "bpmnElement": "Task_2"
                                },
                                "Bounds": [
                                    {
                                        "$": {
                                            "height": "50.0",
                                            "width": "110.0",
                                            "x": "100.0",
                                            "y": "175.0"
                                        }
                                    }
                                ]
                            },
                            {
                                "$": {
                                    "id": "BPMNShape_ExclusiveGateway_2",
                                    "bpmnElement": "ExclusiveGateway_2",
                                    "isMarkerVisible": "true"
                                },
                                "Bounds": [
                                    {
                                        "$": {
                                            "height": "50.0",
                                            "width": "50.0",
                                            "x": "250.0",
                                            "y": "175.0"
                                        }
                                    }
                                ]
                        }// it continues

Answer 1

我并不完全符合您的要求，但undefined与null不同。在您的代码中，只有在f(elem)真实时才会返回，因此所有其他情况下结果将为undefined（因为您没有返回任何其他内容）。如果你的代码失败了一个更复杂的对象，那么它一定不能找到任何东西。

编辑：在查看您的示例数据后，我看不到id字段与bpmnElement匹配的任何位置，因此您的查找功能永远不会找到任何内容。

Answer 2

尝试：

var mapToModel = function(res){
  var processes = res.definitions.process;
  var diagrams = res.definitions.BPMNDiagram; 
  var documents = [];
  for(var prop in processes) {
    if(processes.hasOwnProperty(prop)){
      var propertyNames = Object.getOwnPropertyNames(processes[prop]);
      for(var property in processes[prop]){
        var mapping ={};
        if(property==="$"){
          //do something with the process
        }else{
        //shapes
          mapping.hash = hash.hashCode(new Date().toString());
          mapping.type = property;
          mapping.value = processes[prop][property];
          var bpmnItem = find(processes[prop][property], function(x) {return x.$.id;});
          var bpmnId = bpmnItem.$.id;//value is ok

            if(bpmnId!=undefined){
              var returnVal;
              find(diagrams,function(x){

                if( x.$ != undefined && x.$.bpmnElement != undefined ){

                  if(x.$.bpmnElement===bpmnId){
                    {returnVal =  x;}
                  }
                }
              });

              console.log("return:"+ returnVal);
          }
          documents.push(mapping);
        }
      }
    }
     return documents;
  }
}

在node.js中调用递归函数时的空值

2 个答案: