Question

我有一个json，想获取一些值（如果存在或不为null）。从JSON下面，我想提取“ questionGroup”的“ options”。挑战在某些地方“ questionGroup”是空的。

"surveyQuestions": [
    {
      "questionTitle": "Enter your name",
      "questionType": "Text",
      "questionGroup": {}
    },
    {
      "questionTitle": "Enter your age",
      "questionType": "Number",
      "questionGroup": {}
    },
    {
      "questionTitle": "Select your gender",
      "questionType": "Single choice",
      "questionGroup": {
        "options": [
          {
            "optionText": "Male"
          },
          {
            "optionText": "Female"
          }
        ],
        "showRemarksBox": false
      }
    }
  ]

Answer 1

只需检查选项是否未定义。

// Iterate over survey questions
this.surveyQuestions.forEach( question => {
    // Check if present or not
    if(question.questionGroup.options!=undefined){
        console.log(question.questionGroup.options);
        return question.questionGroup.options;
    }
});

Answer 2

您可以为此使用filter方法。

let data = {"surveyQuestions": [
    {
      "questionTitle": "Enter your name",
      "questionType": "Text",
      "questionGroup": {}
    },
    {
      "questionTitle": "Enter your age",
      "questionType": "Number",
      "questionGroup": {}
    },
    {
      "questionTitle": "Select your gender",
      "questionType": "Single choice",
      "questionGroup": {
        "options": [
          {
            "optionText": "Male"
          },
          {
            "optionText": "Female"
          }
        ],
        "showRemarksBox": false
      }
    }
  ]}

let result = Array.from(data.surveyQuestions.filter(o => o.questionGroup.options), ({questionGroup}) => questionGroup.options);
console.log(result);

Answer 3

surveyQuestions.filter(s => s.questionGroup && Object.keys(s.questionGroup).length)

如何从JSON中获取特定值（如果存在）

3 个答案: