从JSON对象中的数组获取数据

时间：2018-11-15 07:11:55

标签： javascript arrays json

我需要获取timestamp中new_name已已解决的对象的status_change。

我已经尝试过了。

console.log(
 ticket.updates ? 
 (
  (ticket.updates.find(x => x.status_change !== null) && 
   ticket.updates.find(x => x.status_change !== null).status_change.new_name === 'Solved') ?
  ticket.updates.find(x => x.status_change !== null).timestamp : 
   'new_name is ' + ticket.updates.find(x => x.status_change !== null).status_change.new_name
 ) 
 : 'No updates');

但是上面的代码没有给出预期的结果。

这是我的数据集。

{
    "updates": [{
            "timestamp": "2018-04-26 06:39:12",
            "by": {
                "name": "A1"
            },
            "status_change": {
                "new_name": "Open",
                "old_name": null
            }
        }, {
            "timestamp": "2018-04-27 00:09:44",
            "by": {
                "name": "B1"
            },
            "status_change": null
        }, {
            "timestamp": "2018-04-27 00:10:09",
            "by": {
                "name": "B1"
            },
            "status_change": {
                "new_name": "Solved",
                "old_name": "Open"
            }
        }
    ]
}

可能是什么问题？ JSFiddle

6 个答案:

答案 0 :(得分：1)

您可以在find()中使用多个布尔来使其短路，因此您不需要重复的find()调用：

let obj = {"updates": [{"timestamp": "2018-04-26 06:39:12","by": {"name": "A1"},"status_change": {"new_name": "Open","old_name": null}}, {"timestamp": "2018-04-27 00:09:44","by": {"name": "B1"},"status_change": null}, {"timestamp": "2018-04-27 00:10:09","by": {"name": "B1"},"status_change": {"new_name": "Solved","old_name": "Open"}}]}

let item = obj.updates.find(item => 
   item.status_change
   && item.status_change.new_name == "Solved")

if (item) { // found one
  console.log(item.timestamp)
} else {   // not found
  console.log("no new items")
}

答案 1 :(得分：1)

您可以首先使用.filter()过滤掉不需要的对象。然后使用.map()获取必要的字段。

方法如下：

const data = {
    "updates": [{
            "timestamp": "2018-04-26 06:39:12",
            "by": {
                "name": "A1"
            },
            "status_change": {
                "new_name": "Open",
                "old_name": null
            }
        }, {
            "timestamp": "2018-04-27 00:09:44",
            "by": {
                "name": "B1"
            },
            "status_change": null
        }, {
            "timestamp": "2018-04-27 00:10:09",
            "by": {
                "name": "B1"
            },
            "status_change": {
                "new_name": "Solved",
                "old_name": "Open"
            }
        }
    ]
}

const timestamps = data.updates
  .filter(x => x.status_change && x.status_change.new_name === 'Solved')
  .map(x => x.timestamp);

if(timestamps.length >= 1) {
  console.log('updates:', timestamps);
} else {
  console.log('no updates');
}

答案 2 :(得分：1)

好吧，不要在条件中使用.find()，而最好使用为此目的而设计的.some()，并且也只能使用一个.some()调用来对所有这些条件进行分组。

除了编写x.status_change != null之外，您还可以编写x.status_change来得到相同的结果。

console.log(
    ticket.updates ?
      ticket.updates.some(x => x.status_change && x.status_change.new_name === 'Solved') ?
        ticket.updates.find(x => x.status_change && x.status_change.new_name === 'Solved').timestamp :
        'new_name is ' + ticket.updates.find(x => x.status_change).status_change.new_name
      : 'No updates');

演示： 

let ticket = {
  "updates": [{
    "timestamp": "2018-04-26 06:39:12",
    "by": {
      "name": "A1"
    },
    "status_change": {
      "new_name": "Open",
      "old_name": null
    }
  }, {
    "timestamp": "2018-04-27 00:09:44",
    "by": {
      "name": "B1"
    },
    "status_change": null
  }, {
    "timestamp": "2018-04-27 00:10:09",
    "by": {
      "name": "B1"
    },
    "status_change": {
      "new_name": "Solved",
      "old_name": "Open"
    }
  }]
};


console.log(
    ticket.updates ?
      ticket.updates.some(x => x.status_change && x.status_change.new_name === 'Solved') ?
        ticket.updates.find(x => x.status_change && x.status_change.new_name === 'Solved').timestamp :
        'new_name is ' + ticket.updates.find(x => x.status_change).status_change.new_name
      : 'No updates');

答案 3 :(得分：0)

下面的代码将满足您的要求。 solvedData将包含对象的时间戳，其中status_change已已解决。请参见下面的代码。随时解决任何问题。

var myData = {
    "updates": [{
            "timestamp": "2018-04-26 06:39:12",
            "by": {
                "name": "A1"
            },
            "status_change": {
                "new_name": "Open",
                "old_name": null
            }
        }, {
            "timestamp": "2018-04-27 00:09:44",
            "by": {
                "name": "B1"
            },
            "status_change": null
        }, {
            "timestamp": "2018-04-27 00:10:09",
            "by": {
                "name": "B1"
            },
            "status_change": {
                "new_name": "Solved",
                "old_name": "Open"
            }
        }
    ]
};

var solvedData = [];

var i=0;
if(myData.updates){
    for(i=0;i<myData.updates.length; i++){
        if(myData.updates[i].status_change && myData.updates[i].status_change.new_name === "Solved"){
            solvedData.push(myData.updates[i].timestamp);
        }
    }
}

  for(i=0;i<solvedData.length; i++){
    console.log(solvedData[i]);
  }

答案 4 :(得分：0)

这应该有效

  • 过滤现有的status_change
  • 过滤new_name ===“已解决”
  • 映射时间戳

const tickets = {
  "updates": [{
    "timestamp": "2018-04-26 06:39:12",
    "by": {
      "name": "A1"
    },
    "status_change": {
      "new_name": "Open",
      "old_name": null
    }
  }, {
    "timestamp": "2018-04-27 00:09:44",
    "by": {
      "name": "B1"
    },
    "status_change": null
  }, {
    "timestamp": "2018-04-27 00:10:09",
    "by": {
      "name": "B1"
    },
    "status_change": {
      "new_name": "Solved",
      "old_name": "Open"
    }
  }]
};
console.log(tickets.updates
  .filter(x => x.status_change && x.status_change.new_name === "Solved")
  .map(x => x.timestamp));

答案 5 :(得分：0)

也许是最愚蠢的，但恕我直言是最简单的解决方案：

var ticket = {"updates":[{"timestamp":"2018-04-26 06:39:12","by":{"name":"A1"},"status_change":{"new_name":"Open","old_name":null}},{"timestamp":"2018-04-27 00:09:44","by":{"name":"B1"},"status_change":null},{"timestamp":"2018-04-27 00:10:09","by":{"name":"B1"},"status_change":{"new_name":"Solved","old_name":"Open"}}]};

for (var i in ticket.updates ) {
    var item=ticket.updates[i];
    if (typeof item.status_change === 'object' && item.status_change !== null) {
             if (item.status_change.new_name === 'Solved') {
                    alert('Found timestamp value: ' + item.timestamp);
             }
    }
}
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