到目前为止，我已经收到了一些关于 Parse Promise 的优秀信息，并准备好解决我的下一个难题......关系。以下代码大部分是在回答Issues with Parse Cloud Code Promises但我在代码段的注释中提出了我的下一个问题。我将如何进一步查询顶级关系中的关系？很高兴看到您如何扩展代码来做到这一点@roamer-1888
最新:
//Return a single project
Parse.Cloud.define('getProjectByUrl', 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.include("projectStatus"); // *MJ Added the include to add the project Status pointer
query.find().then(function(projectsResult) {
var project = projectsResult[0];
//From here, `project` is hierarchically monkey-patched with the results of further queries.
//Make tags query, the referees query and the sections query in parallel.
var tagsPromise = project.relation('tags').query().find();
var refereesPromise = project.relation('referees').query().find();
var sectionsPromise = project.relation('sections').query().include("sectionType").find(); //*MJ Added the include of the sectionType pointer
// Aggregate the three promises with Parse.Promise.when(), and handle the responses.
return Parse.Promise.when(tagsPromise, refereesPromise, sectionsPromise).then(function(tags, referees, sections) {
project.set('tags', tags);
project.set('referees', referees);
project.set('sections', sections);
//Go deeper into `sections`
var sectionsRelationsPromises = sections.map(function(section) {
// *MJ Remove sectionTypesPromise as it's a pointer
var filesPromise = section.relation('files').query().include("fileType").find(); // *MJ Added the include to grab the fileType pointer
return Parse.Promise.when(filesPromise).then(function(files) {
//*MJ Removed the promise for section Types
section.set('files', files);
// *MJ Removed the Deeper Logic
});
});
return Parse.Promise.when(sectionsRelationsPromises);
}).then(function() {
return project;
});
}).then(function(project) {
// At this point, all the data is gathered in the form of Parse objects in project,
// which now needs to be mapped into a js plain object.
var projectData = projectObj(project);
projectData.tags = project.get('tags').map(tagObj); //Process the tags response
projectData.referees = project.get('referees').map(refereeObj); // *MJ removed one e from refereeObj //Process the referees response
projectData.sections = project.get('sections').map(sectionObj); //Process the sections response
// *MJ Removed the adding of the files and looking over the sections.
//Yay! (hopfully)
response.success(projectData);
}).fail(function(error) {
response.error('Error: ' + error);
});
// ***********************************
// ***** start: mapper functions *****
// ***********************************
function projectObj(project) {
return { // *MJ Removed the stray equals sign here
'id': project.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").get("status") //*MJ Added the get of the Project Status status.
}
}
function tagObj(tag) {
return {
'tag': tag.get('tag')
};
}
function refereeObj(referee) {
return {
'name': referee.get('name'),
'role': referee.get('role'),
'emailAddress': referee.get('emailAddress'),
'phoneNumber': referee.get('phoneNumber'),
'linkedInUrl': referee.get('linkedInUrl')
};
}
function sectionObj(section) {
return {
'type': section.get('sectionType').get("type"), // *MJ Added the pointer for SectionType > type
'order': section.get('order'),
'content': section.get('content'),
'files': section.get('files').map(fileObj)
};
}
function fileObj(file) {
return {
'name': file.get('name'), // *MJ chnaged the name to be more appropriate
'url': file.get('url'), // *MJ Added the missing comma
'type': file.get('fileType').get("type") //*MJ Added the pointer for fileType > type and removed semi colon
};
}
// *********************************
// ***** fin: mapper functions *****
// *********************************
});
旧:
//Return a single project
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.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')
};
//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();
var sectionsPromise = project.relation('sections').query().find();
var sectionTypesPromise = project.relation('sections').query().find().relation('type').query().find();
var filesPromise = project.relation('sections').query().find().relation('files').query().find();
var fileTypesPromise = project.relation('sections').query().find().relation('files').query().find().relation('type').query().find();
// Aggregate the two promises with Parse.Promise.when(), and handle the responses.
return Parse.Promise.when(tagsPromise, refereesPromise, sectionsPromise, sectionTypesPromise, filesPromise, fileTypesPromise).then(function(tags, referees, sections, sectionTypes, files, fileTypes) {
//Process the tags response
projectData.tags = tags.map(function(tag) {
return {
'tag': tag.get('tag')
};
});
//Process the referees response
projectData.referees = referees.map(function(refereee) {
return {
'name': refereee.get('name'),
'role': refereee.get('role'),
'emailAddress': refereee.get('emailAddress'),
'phoneNumber': refereee.get('phoneNumber'),
'linkedInUrl': refereee.get('linkedInUrl')
};
});
//Process the sections response
projectData.sections = sections.map(function(section) {
return {
'order': section.get('order'),
'content': section.get('content')
};
});
// Problem: Sections have a relations column (files)
// which I would like to return as a child of sections.
// The files class then has a pointer column (type)
// to another class which contains the a list of
// file types (i.e. Image, Document, etc...)
// The sections structure of projectDate should
// look like:
//
// "sections": [{
// "type": "Section Type"
// "order": "1",
// "content": "This is the Section content",
// "files": [{
// "filename": "Image 1",
// "url": "image-1.png"
// "type": "Image"
// },
// {
// "filename": "Image 2",
// "url": "image-2.png",
// "type": "Image"
// },
// {
// ...
// }]
// },
// {
// ...
// }
// }]
//Process the section type response. This is reliant on sections being retrieved.
projectData.sections.type = sections.map(function(sectionTypes) {
return {
'type': sectionTypes.get('type')
};
});
//Process the section files response. This is reliant on sections being retrieved.
projectData.sections.files = sections.map(function(files) {
return {
'filename': files.get('filename'),
'url': files.get('url')
};
});
//Process the section files types response. This is reliant on files being retrieved.
projectData.sections.files.type = sections.map(function(fileTypes) {
return {
'type': fileTypes.get('type')
};
});
// Currently not so Yay!
response.success(projectData);
});
}).fail(function(error) {
response.error('Error: ' + error);
});
});
最佳答案
深入一层会稍微复杂一些。每个级别都需要一个与顶级模式非常相似的模式。
不幸的是，这些模式本身并不适合“扁平”。不断引用早期结果的需要使得嵌套很有吸引力，尽管可能不是绝对必要的；我确信还存在其他方法。
这是对代码的尝试。由于无法测试，很可能会出现错误。
//Return a single project
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];
//From here, `project` is hierarchically monkey-patched with the results of further queries.
//Make tags query, the referees query and the sections query in parallel.
var tagsPromise = project.relation('tags').query().find();
var refereesPromise = project.relation('referees').query().find();
var sectionsPromise = project.relation('sections').query().find();
// Aggregate the three promises with Parse.Promise.when(), and handle the responses.
return Parse.Promise.when(tagsPromise, refereesPromise, sectionsPromise).then(function(tags, referees, sections) {
project.set('tags', tags);
project.set('referees', referees);
project.set('sections', sections);
//Go deeper into `sections`
var sectionsRelationsPromises = sections.map(function(section) {
var sectionTypesPromise = section.relation('type').query().find();
var filesPromise = section.relation('files').query().find();
return Parse.Promise.when(sectionTypesPromise, filesPromise).then(function(sectionTypes, files) {
section.set('type', sectionTypes[0]);
section.set('files', files);
//And deeper still into each of the section's files to find their types
var filesRelationsPromises = files.map(function(file) {
return file.relation('type').query().find().then(function(fileTypes) {
file.set('type', fileTypes[0]);
});
});
return Parse.Promise.when(filesRelationsPromises);
});
});
return Parse.Promise.when(sectionsRelationsPromises);
}).then(function() {
return project;
});
}).then(function(project) {
// At this point, all the data is gathered in the form of Parse objects in project,
// which now needs to be mapped into a js plain object.
var projectData = projectObj(project);
projectData.tags = project.get('tags').map(tagObj); //Process the tags response
projectData.referees = project.get('referees').map(refereeeObj); //Process the referees response
projectData.sections = project.get('sections', sections).map(sectionObj); //Process the sections response
projectData.sections.each(function(section) {
section.files = section.get('files').map(fileObj);
});
//Yay! (hopfully)
response.success(projectData);
}).fail(function(error) {
response.error('Error: ' + error);
});
// ***********************************
// ***** start: mapper functions *****
// ***********************************
function projectObj(project) {
return = {
'id': project.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')
}
}
function tagObj(tag) {
return {
'tag': tag.get('tag')
};
}
function refereeObj(referee) {
return {
'name': referee.get('name'),
'role': referee.get('role'),
'emailAddress': referee.get('emailAddress'),
'phoneNumber': referee.get('phoneNumber'),
'linkedInUrl': referee.get('linkedInUrl')
};
}
function sectionObj(section) {
return {
'type': section.get('type'),
'order': section.get('order'),
'content': section.get('content'),
'files': section.get('files').map(fileObj)
};
}
function fileObj(file) {
return {
'filename': file.get('filename'),
'url': file.get('url')
'type': file.get('type');
};
}
// *********************************
// ***** fin: mapper functions *****
// *********************************
});
我已使代码尽可能简单以便遵循:
- 将第一个 .then 的回调限制为异步收集数据。
- 在后续 .then 回调中编排所收集数据的映射。
- 最后将各个映射器函数拉到一个单独的部分中。
相信我，这比在单个 block 中执行所有操作更具可读性。我试过了，这简直就是噩梦。
调试愉快。
关于javascript - 使用 Promise 时返回 Parse Cloud Code 中更深层次的关系，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34146245/