解析雲代碼承諾的問題

Question

我正在嘗試使用解析雲代碼並使用承諾來確保我消除了cals是異步的任何問題。我想查詢一個類，取回一個對象，建立一些JSON，然後查詢對象的某些關係（標籤，裁判），並將它們添加到JSON中以返回ExpressJS進行渲染。我粘貼的代碼不起作用，但我不明白爲什麼每次我回到項目中尋找下一個承諾。

編輯：

//Return a single project 
Parse.Cloud.define('getProject', function(request, response) { 
    var projectUrl = request.params.projectUrl; 

    var project; 
    var projectsData = []; 

    var Projects = new Parse.Object("projects"); 
    var query = new Parse.Query(Projects); 
    query.equalTo("projectUrl", projectUrl); 
    query.find().then(function(projectsResult) { 
     console.log(projectsResult.length + " Projects returned"); 

     project = projectsResult[0]; 
     var projectData = { 
      "id": project.get("id"), 
      "title": project.get("title"), 
      "previewImage": project.get("previewImage"), 
      "longDescription": project.get("longDescription"), 
      "shortDescription": project.get("shortDescription"), 
      "visibleToPublic": project.get("visibleToPublic"), 
      "dateStart": project.get("dateStart"), 
      "dateEnd": project.get("dateEnd"), 
      updatedAt: project.get("updatedAt"), 
      projectStatus: project.get("projectStatus") 
     }; 

     projectsData.push(projectData); 
     console.log("Step 1. Projects Data: " + JSON.stringify(projectsData)); 

     var tagsQuery = project.relation('tags'); 
     return tagsQuery.query().find(); 
    }).then(function(tags) { 
     var tagsData = []; 
     for(var t = 0; t < tags.length; t++) { 
      var tagData = { 
       "tag": tags[t].get("tag"), 
      } 
      console.log("Tag Data: " + tagData); 
      tagsData.push(tagData); 
     } 
     projectsData[tags] = tagsData; 
     console.log("Step 2. Tags Data: " + JSON.stringify(tagsData)); 

     var refereesQuery = project.relation('referees'); 
     return refereesQuery.query().find(); 
    }).then(function(referees) { 
     var refereesData = []; 
     for(var r = 0; r < referees.length; r++) { 
      var refereeData = { 
       "name": referees[r].get("name"), 
       "role": referees[r].get("role"), 
       "emailAddress": referees[r].get("emailAddress"), 
       "phoneNumber": referees[r].get("phoneNumber"), 
       "linkedInUrl": referees[r].get("linkedInUrl"), 
      } 
      console.log("Referee Data: " + refereeData); 
      refereesData.push(refereeData); 
     } 
     projectsData[referees] = refereesData; 
     console.log("Step 3. Referees Data: " + JSON.stringify(refereesData)); 

     console.log("Everthing should be part of Projects Data here: " + JSON.stringify(projectsData)); 

     response.success(projectsData); 
    }, function(error) { 
     response.error("Error: " + error); 
    }); 
}); 

Answer 1

有幾個問題：

• 混亂和projectData之間projectsData
• projectsData實際上不是必要的。
• projectData需要在創建&後指定的三個地方使用（或應該使用）。
• 在幾種情況下，.then()用於標準同步流就足夠了。清除不必要的.thens將有助於清理範圍問題。

做得比周圍洗牌碼多一點，我在下面抵達：

Parse.Cloud.define('getProject', function(request, response) { 
    var Projects = Parse.Object.extend("projects"); // with credit to @kRiZ 
    var query = new Parse.Query(Projects); 
    query.equalTo('projectUrl', request.params.projectUrl); 
    query.find().then(function(projectsResult) { 
     var project = projectsResult[0]; 
     var projectData = { 
      'id': project.get('id'), 
      'title': project.get('title'), 
      'previewImage': project.get('previewImage'), 
      'longDescription': project.get('longDescription'), 
      'shortDescription': project.get('shortDescription'), 
      'visibleToPublic': project.get('visibleToPublic'), 
      'dateStart': project.get('dateStart'), 
      'dateEnd': project.get('dateEnd'), 
      'updatedAt': project.get('updatedAt'), 
      'projectStatus': project.get('projectStatus') 
     }; 

     //Now make the tags query and the referees query in parallel. 
     var tagsPromise = project.relation('tags').query().find(); 
     var refereesPromise = project.relation('referees').query().find(); 

     // Aggregate the two promises with Parse.Promise.when(), and handle the responses. 
     return Parse.Promise.when(tagsPromise, refereesPromise).then(function(tags, referees) { 
      //Process the tags response 
      projectData.tags = tags.map(function(t) { 
       return { 
        'tag': t.get('tag') 
       }; 
      }); 
      //Process the referees response 
      projectData.referees = referees.map(function(r) { 
       return { 
        'name': r.get('name'), 
        'role': r.get('role'), 
        'emailAddress': r.get('emailAddress'), 
        'phoneNumber': r.get('phoneNumber'), 
        'linkedInUrl': r.get('linkedInUrl') 
       }; 
      }); 
      // Yay! 
      response.success(projectData); 
     }); 
    }).fail(function(error) { 
     response.error('Error: ' + error); 
    }); 
}); 

除了整體重排，唯一的重大變化是：

• 使用Array#map()將數組映射到另一個數組。
• 並行進行兩個查詢並使用Parse.Promise.when()來彙總這兩個承諾。

Answer 2

的問題似乎是與你的初始查詢。你正在嘗試使用子類，但是你的語法是錯誤的。

您的查詢應該開始像這樣：

var Projects = Parse.Object.extend("projects"); 
var query = new Parse.Query(Projects); 

編輯：

而且，你正在返回的對象，您應該返回承諾。下面 見代碼（未測試）：

Parse.Cloud.define('getProject', function(request, response) { 
    var projectUrl = request.params.projectUrl; 
    var projectsData = []; 

    var Projects = Parse.Object.extend("projects"); 
    var query = new Parse.Query(Projects); 
    query.equalTo("projectUrl", projectUrl); 
    query.find().then(function(projectsResult) { 
     console.log(projectsResult.length + " Projects returned"); 

     var project = projectsResult[0]; 
     var projectData = { 
      "id": project.get("id"), 
      "title": project.get("title"), 
      "previewImage": project.get("previewImage"), 
      "longDescription": project.get("longDescription"), 
      "shortDescription": project.get("shortDescription"), 
      "visibleToPublic": project.get("visibleToPublic"), 
      "dateStart": project.get("dateStart"), 
      "dateEnd": project.get("dateEnd"), 
      updatedAt: project.get("updatedAt"), 
      projectStatus: project.get("projectStatus") 
     }; 

     projectsData.push(projectData); 
     console.log("Step 1. Projects Data: " + JSON.stringify(projectsData)); 

     // Removed the return from here 

     var tagsData = []; 
     console.log("Project Step 2: " + JSON.stringify(project)); 
     var tagsQuery = project.relation('tags'); 
     return tagsQuery.query().find(); 
    }).then(function(tags) { 
     for(var t = 0; t < tags.length; t++) { 
      var tagData = { 
       "tag": tags[t].get("tag"), 
      } 
      tagsData.push(tagData); 
     } 
     projectsData.tags = tagsData; 
     console.log("Step 2. Tags Data: " + JSON.stringify(tagsData)); 

     // Removed return from here 

     var refereesData = []; 
     var refereesQuery = project.relation('referees'); 
     return refereesQuery.find(); 
    }).then(function(referees) { 
     for(var r = 0; r < referees.length; r++) { 
      var refereeData = { 
       "name": referees[r].get("name"), 
       "role": referees[r].get("role"), 
       "emailAddress": referees[r].get("emailAddress"), 
       "phoneNumber": referees[r].get("phoneNumber"), 
       "linkedInUrl": referees[r].get("linkedInUrl"), 
      } 
      refereesData.push(refereeData); 
     } 
     projectData.referees =refereesData; 
     console.log("Step 3. Referees Data: " + JSON.stringify(refereesData)); 

     response.success(projectsData); 
    }, function(error) { 
     response.error("Error: " + error); 
    }); 
}); 

上使用子類中檢索數據見解析文檔here。