如何訪問來自不同對象範圍的挖空觀測數據

Question

我的數據模型由兩個對象組成;項目和任務。 我通過JSON和MVC服務加載從DB我的數據和地圖我observableArrays這樣的：

viewModel = function() { 
    var self = this; 

    // some code... 

    // projects 
    self.Projects = ko.observableArray(); 
    var mappedProjects = []; 
    $.ajax({ 
     url: "myService/GetProjectsByUserId", 
     data: "userID=" + meID, 
     dataType: 'json', 
     async: false, 
     success: function (allData) { 
      mappedProjects = $.map(allData, function (item) { 
       return new Project(item); 
      }); 
     } 
    }); 
    self.Projects(mappedProjects); 

    // tasks 
    self.Tasks = ko.observableArray(); 
    var mappedTasks = []; 
    $.ajax({ 
     url: "myService/GetTasksByUserID", 
     data: "userid=" + meID, 
     dataType: 'json', 
     async: false, 
     success: function (allData) { 
      mappedTasks = $.map(allData, function (item) { 
       return new Task(item, self.Projects); // is there a smarter way to access self.Projects from the Scene prototype? 
       //return new Task(item); 
      }); 
     } 
    }); 
    self.Tasks(mappedTasks); 


    //some more code... 

}; 

其中

Project = function (data) { 
    this.projectID = data.projectID; 
    this.type = ko.observable(data.type); 
}; 


Task = function (data, projects) { 

    this.taskID = data.taskID; 
    this.projectID = data.projectID; 

    //this.projecttype = ??? simpler solution? 

    this.projecttype = ko.computed(function() { // Is there a simpler way to access 'viewModel.Projects' from within 'Task'? 
     var project = ko.utils.arrayFirst(projects, function (p) { 
      return p.projectID === self.projectID; 
     }); 
     if (!project) { 
      return null; 
     } 
     else { 
      return project.headerType(); 
     } 
    }); 

}; 

的事情是（你看），我要訪問的項目類型在Task對象內部。有沒有比使用self.Projects作爲輸入實例化對象更簡單的方法？

可以self.Projects被綁定時，以某種方式定義，所以我可以通過DOM訪問它？

Answer 1

從您的意見，它看起來像你有多個視圖模型依賴於Task和Project對象。對於組件之間的解耦，我會說使用ko.postbox插件。您可以使用publishOn和subscribeTo擴展名輕鬆實現視圖模型和非基礎組件之間的同步。

所以你Task對象將認購ProjectsobservableArray在視圖模型像

Task = function (data) { 

    this.taskID = data.taskID; 
    this.projectID = data.projectID; 
    var projects = ko.observableArray().subscribeTo("projectsLoaded",true); 

    //this.projecttype = ??? simpler solution? 

    this.projecttype = ko.computed(function() { // Is there a simpler way to access 'viewModel.Projects' from within 'Task'? 
     var project = ko.utils.arrayFirst(projects(), function (p) { 
      return p.projectID === self.projectID; 
     }); 
     if (!project) { 
      return null; 
     } 
     else { 
      return project.headerType(); 
     } 
    }); 

}; 

，並在您的視圖模型，你就必須讓項目可觀測陣列發佈「projectsLoaded」主題/事件。像

viewModel = function() { 
    var self = this; 
    // some code... 
    // projects 
    self.Projects = ko.observableArray().publishOn("projectsLoaded"); 
    // .... 
} 

每當視圖模型的projects數組的變化，你將永遠在任務project陣列的最新值。

JsFiddle：http://jsfiddle.net/newuserjs/wffug341/3/