從JSON響應中解析一個始終更改順序的值

Question

我試圖從javscript中的家庭自動化系統解析JSON響應。 響應是 available here

那只是響應的一小部分，另外，在每次系統啓動鍵變化的原因，我不知道，蘇使用了數字索引的順序不會真的管用 我需要能夠將sensor.out，sensor.in，sensor.door的狀態值存儲到tasker on和oridid的變量中 我試圖使用entity.id進行選擇，但由於某種原因代碼從未完成（我相信我只是沒有知道我在做什麼）

Answer 1

隨着ES6可以使用Array#find方法：

response.find(o => o.entity_id == 'sensor.out').state 

見片段：

var response = [ { "attributes":{ "friendly_name":"door" }, "entity_id":"sensor.door", "last_changed":"2016-12-31T11:15:59.395808+00:00", "last_updated":"2016-12-31T11:15:59.395808+00:00", "state":"closed" }, { "attributes":{ "friendly_name":"In", "unit_of_measurement":"\u00b0C" }, "entity_id":"sensor.in", "last_changed":"2016-12-31T11:20:02.179821+00:00", "last_updated":"2016-12-31T11:20:02.179821+00:00", "state":"20.7" }, { "attributes":{ "changed_by":null, "code_format":".+", "friendly_name":"panel" }, "entity_id":"alarm_control_panel.panel", "last_changed":"2016-12-31T11:14:56.471966+00:00", "last_updated":"2016-12-31T11:14:56.471966+00:00", "state":"disarmed" }, { "attributes":{ "friendly_name":"Out", "unit_of_measurement":"\u00b0C" }, "entity_id":"sensor.out", "last_changed":"2016-12-31T11:14:58.452345+00:00", "last_updated":"2016-12-31T11:14:58.452345+00:00", "state":"7.1" }]; 
 
var state = response.find(o => o.entity_id == 'sensor.out').state; 
 
console.log('sensor.out state is', state);

或者，你可以在響應轉換爲對象用實體ID值作爲鍵，所以你可以一個CCESS它像response['session.out'].state：

response = Object.assign({}, ...response.map(o => ({[o.entity_id]: o}))); 

見片段：

var response = [ { "attributes":{ "friendly_name":"door" }, "entity_id":"sensor.door", "last_changed":"2016-12-31T11:15:59.395808+00:00", "last_updated":"2016-12-31T11:15:59.395808+00:00", "state":"closed" }, { "attributes":{ "friendly_name":"In", "unit_of_measurement":"\u00b0C" }, "entity_id":"sensor.in", "last_changed":"2016-12-31T11:20:02.179821+00:00", "last_updated":"2016-12-31T11:20:02.179821+00:00", "state":"20.7" }, { "attributes":{ "changed_by":null, "code_format":".+", "friendly_name":"panel" }, "entity_id":"alarm_control_panel.panel", "last_changed":"2016-12-31T11:14:56.471966+00:00", "last_updated":"2016-12-31T11:14:56.471966+00:00", "state":"disarmed" }, { "attributes":{ "friendly_name":"Out", "unit_of_measurement":"\u00b0C" }, "entity_id":"sensor.out", "last_changed":"2016-12-31T11:14:58.452345+00:00", "last_updated":"2016-12-31T11:14:58.452345+00:00", "state":"7.1" }]; 
 
response = Object.assign({}, ...response.map(o => ({[o.entity_id]: o}))); 
 
console.log('sensor.out state is', response['sensor.out'].state);

Answer 2

如果你想使用索引來選擇對象的屬性，你不應該，除非有非常特殊的理由這樣做。

幸運的是，這很好，你不需要知道順序。我從你的JSON數組中取出了兩個對象，對這些屬性進行了編碼，然後編寫了一個函數，返回包含您指定的鍵/ val的任何對象。

你的問題有點難以遵循，但我認爲這會給你的想法。

<script type="text/javascript"> 
let arr = [ 
    { 
    "attributes":{ 
     "friendly_name":"door" 
    }, 
    "entity_id":"sensor.frontdoor", 
    "last_changed":"2016-12-31T11:15:59.395808+00:00", 
    "last_updated":"2016-12-31T11:15:59.395808+00:00", 
    "state":"closed" 
    }, 
    { 
    "last_changed":"2016-12-31T11:15:59.395808+00:00", 
    "state":"closed", 
    "attributes":{ 
     "friendly_name":"door" 
    }, 
    "entity_id":"sensor.backdoor", 
    "last_updated":"2016-12-31T11:15:59.395808+00:00" 
    } 
]; 

function findKey (theKey, theVal) { 
    let reduced = arr.filter (d => { 
    return d [ theKey ] === theVal; 
    }); 

    return reduced; 
} 

let targets = findKey ('entity_id', 'sensor.backdoor'); 
targets.forEach (d => { 
    // This check is a little naive, but should give you the idea 
    if ('state' in d) { 
     console.log (d.state); 
    } 
}); 
</script> 

Answer 3

大家說的是正確的：響應中按鍵的順序無關緊要。使用（字符串）鍵，而不是數字索引。

var arr = [ 
    { 
    "entity_id":"sensor.door", 
    "state":"closed" 
    }]; // other attributes chopped out for brevity 

var entity_id_interested_in = 'sensor.door'; 
var state = '[entity_id not found in response]'; 
for (var i = 0; i < arr.length; i++) { 

    console.log(arr[i].entity_id + ' state:' + arr[i].state); 
    if (arr[i].entity_id == entity_id_interested_in) 
    { 
     state = arr[i].state; 
     break; 
    } 
} 
console.log (state);