貓鼬 - 如何從父母的信息更新的子對象自動

Question

有特殊原因，有以下方式的信息，所以我不能改變如何父和子對象涉及：

我有一個包含有關多日展會信息的父對象。有一個子對象引用了展會每一天的信息，這些日子中的每一天都被稱爲事件。我需要在公平對象生成時自動生成事件子對象。然後我需要從生成的子對象中分別生成一個ObjectID的數組。另外，我需要能夠在以後生成不基於公平對象的任意事件對象。這就是爲什麼我有ObjectID的數組，所以我知道自動生成的內容以及用戶生成的內容。

這是我的架構（只是有用的部分）：

/** 
* This is the main object, the user only supplies information for this object 
* name, start and end are all provided by the user, num_days is automatically calculated 
*/ 

var FairSchema = new Schema({ 
name: { 
    type: String, 
    default: '', 
    required: 'Please fill Fair name', 
    trim: true 
}, 
start_date: { 
    type: Date, 
    required: 'Please provide a start date' 
}, 
end_date: { 
    type: Date, 
    required: 'Please provide an end date' 
}, 
num_days: { 
    type: Number, 
    required: true, 
    default: 1 
}, 
events: EventsSchema 
}); 

/** 
* This is the child object it should pull all of it's information from the parent at the time the parent is created if 
* the parent object has more than one day an event child object is created for each day. 
* 
* name: The same as the parent object, unless multiday then it's the name plus 'Day #' 
* start_date: The same as the parent object unless multiday then it's the parent object time + the child object day 
* end_date: the same as the parent object unless multiday then it's the parent object time + the child object day 
* 
*/ 

var EventSchema = new Schema({ 
name: { 
    type: String, 
    required: 'Please provide a name for the event', 
    trim: true 
}, 
start_date: Date, 
end_date: Date, 
}); 

我已經試過這樣的事情在我的控制器，然後把它稱爲公平的對象保存之前：

initializeFairEvents = function (fair) { 
var fairLengthDays = fair.num_days; 
var eventStart = Date.parse(fair.start_date); 
var eventEnd = Date.parse(fair.end_date); 
var one_day = (24 * 60 * 60 * 1000); 
var events = fair.events; 
var dailyEventLength = eventEnd - eventStart - one_day*(fairLengthDays-1); 

if (events !== null && events.length > 0){} 
else { 
    for (var i = 0; i < fairLengthDays; i++) { 
     var name, start_date, end_date, preserve; 
     start_date = (i * one_day) + eventStart; 
     end_date = (i * one_day) + eventStart + dailyEventLength; 
     preserve = true; 
     if (fairLengthDays === 1) { 
      name = fair.name; 
     } else { 
      name = fair.name + ' - day ' + (i + 1).toString(); 
     } 
     fair.events.push({ 
      name: name, 
      start_date: start_date, 
      end_date: end_date, 
      preserve: preserve 
     }); 
    } 
} 

};

但是當時我沒有對象ID的，因爲什麼都沒有去該數據庫有ID的生成。

我覺得我陷入了一個循環。任何提示或想法，將不勝感激。

Answer 1

由於您使用的貓鼬，您可以創建從模型構造函數的局部模型實例（假設Event的事件），像這樣：

var event = Event(); 

或者，如果你只有父模型實例（假設fair公平）你可以使用subdoc的create方法：

var event = fair.events.create(); 

您還可以將對象的構造函數，只要它們是相同的形式預期模型。返回的實例將自動包含將由MongoDB使用的對象ID。

這就是說，subdoc的陣列push方法應該自動做到這一點，每個陣列項目應該有一個ID。在保存父文檔之前，這些都不在遠程數據庫上。

var one_day = 86400000; // (24 * 60 * 60 * 1000) no sense in computing a static value 

initializeFairEvents = function(fair) { 
    // Assuming fair is a model instance 
    var fairLengthDays = fair.num_days; 
    var eventStart = Date.parse(fair.start_date); 
    var eventEnd = Date.parse(fair.end_date); 
    var events = fair.events; 
    var dailyEventLength = eventEnd - eventStart - one_day * (fairLengthDays - 1); 

    // It looks like you only want to add events if there are no events currently 
    if (events === null || events.length === 0) { 
    for (var i = 0; i < fairLengthDays; i++) { 
     var newEvent = fair.events.create({ 
     name: (fairLengthDays === 1) ? 
      fair.name : 
      (fair.name + ' - day ' + (i + 1)), 
     start_date: (i * one_day) + eventStart, 
     end_date: (i * one_day) + eventStart + dailyEventLength, 
     preserve: true 
     }); 

     // newEvent.id 

     fair.events.push(newEvent); 
    } 
    } 
};