单个 Http 请求获取多个文件数据 Parse.com
Single Http Request to get multiple file data Parse.com
我正在使用 Back4app。
我的个人资料class 架构有 4 个包含图片的文件列。
所以当我检索一个对象时，我必须为每个文件发出 HTTP 请求 URL 并像这样获取字节数据。
const data = await Parse.Cloud.httpRequest({url:profilePhoto.url()});
return data.buffer.toString('base64');
但是对于所有四个文件，我必须向服务器发出 4 个 HTTP 请求。
无论如何做一个批处理 HTTP 请求，这样我只需 1 个请求就可以获得所有 4 个文件的数据？
我的主要目标是尽可能减少对服务器的请求。
在 Parse Server 中没有通过一个请求检索多个文件的现成方法。
您可以实现自己的 Parse Cloud Code 功能来检索多个文件，但您必须手动将它们组合到服务器端并在客户端分离它们。
作为起点，您可以查看像 multistream 这样的包，它们允许您将多个文件流合并为一个文件流以获得一些灵感。
您也许可以做一些类似于我在云代码中所做的事情。
我不得不在我的应用程序开始时加载一堆信息，需要多次往返服务器。
所以我写了一个叫做 getUserData() 的函数。
这会执行许多不相关的查询，并将所有结果压缩到一个大对象中。然后我 return 来自函数的对象。
这是整个函数：
console.log("startig getUserData");
var callCount = 0;
var lastLoadTime=0;
// Given a user, load all friends. Save the objects to ret.objects,
// and save the objectIds to ret.friends
//
// Note: we always load the exhaustive friend list, because
// otherwise, we would have no way of recognizing
// removed friendships.
//
async function loadFriends(user, ret) {
const friendQuery = user.relation("friends").query();
const friends = await findFully(friendQuery);
for(var i=0;i<friends.length;i++){
ret.friends[friends[i].id]=1;
ret.objects[friends[i].id]=friends[i];
};
}
// Given a user, load all owned cells. Save the objects to ret.owned,
// and save their objectIds to ret.ownedCells.
//
// Also, save the ids of members, which we will use to flesh out ret.objects with
// the objects who are not friends, but share a cell with the current user.
async function loadPublicCells(user, ret, memberIds) {
const ownedCellQ = new Parse.Query('PublicCell');
ownedCellQ.equalTo('owner',user);
const joinedCellQ = new Parse.Query('PublicCell');
joinedCellQ.equalTo('members',user);
const publicCellQ = Parse.Query.or(ownedCellQ,joinedCellQ);
publicCellQ.greaterThan("updatedAt",new Date(lastLoadTime));
const publicCells=await findFully(publicCellQ);
for(var i=0;i<publicCells.length;i++) {
const cell = publicCells[i];
ret.ownedCells[cell.id]=cell;
const owner = cell.get("owner");
if(owner==null)
continue;
ret.objects[cell.id]=cell;
if(owner.id === user.id) {
ret.ownedCells[cell.id]=1;
} else {
ret.joinedCells[cell.id]=1;
};
const memberQ = cell.relation("members").query();
const members = await findFully(memberQ);
if(ret.memberMap[cell.id]==null)
ret.memberMap[cell.id]={};
const map = ret.memberMap[cell.id];
for(var j=0;j<members.length;j++){
const member=members[j];
map[member.id]=1;
ret.objects[member.id]=member;
};
};
};
// given a list of all members of all cells, load those objects and store
// them in ret.objects. We do not have to record which cells they belong
// to, because that information is in ret.memberMap
async function loadMembers(memberIds, ret) {
const memberQ = new Parse.Query(Parse.User);
var partIds;
while(memberIds.length){
partIds = memberIds.splice(0,100);
memberQ.containedIn('objectId',partIds);
const part = await findFully(memberQ);
for(var i=0;i<part.length;i++) {
ret.objects[part[i].id]=part[i];
}
};
};
// given a user, save all of the objectIds of people who have annoyed him with
// spam. We save only the ids, they don't go on ret.objects, because we only
// need to filter them out of things. The objectIds are sufficient.
//
// We always send all spam objects, otherwise we would not recognize deletions
async function loadUserSpams(user, ret) {
const userSpamsQ = new Parse.Query("_User");
userSpamsQ.equalTo("spamUsers",user);
userSpamsQ.greaterThan("updatedAt", new Date(lastLoadTime));
const userSpams = await findFully(userSpamsQ);
for(var i=0;i<userSpams.length;i++){
ret.userSpams[userSpams[i].id]=1;
};
};
// given a user, save all of the objectIds of people who have been annoyed *BY*
// him with spam. We save only the ids, they don't go on ret.objects, because we
// only need to filter them out of things. The objectIds are sufficient.
//
// We always send all spam objects, otherwise we would not recognize deletions
async function loadSpamUsers(user, ret) {
const spamUserR = user.relation('spamUsers');
const spamUserQ = spamUserR.query();
spamUserQ.greaterThan("updatedAt", new Date(lastLoadTime));
const spamUsers = await findFully(spamUserQ);
for(var i=0;i<spamUsers.length;i++){
ret.spamUsers[spamUsers[i].id]=1;
};
};
// given a user, save all of the objectIds of people to whom he has sent a
// friend request which is still pending. We save only the ids, they don't go
// on ret.objects, because we only need to filter them out of things. The
// objectIds are sufficient.
async function loadPendingFriends(user, ret) {
const request1Q = new Parse.Query('Request');
request1Q.equalTo("owner",user);
const request2Q = new Parse.Query('Request');
request2Q.equalTo("sentTo",user);
const requestQ = Parse.Query.or(request1Q,request2Q);
requestQ.equalTo("status",'PENDING');
const requests = await findFully(requestQ);
for(var i=0;i<requests.length;i++){
const request = requests[i];
const sentBy = request.get("owner");
if(sentBy==null){
console.warn("sentBy==null");
continue;
};
const sentTo = request.get("sentTo");
if(sentTo==null){
console.warn("sentTo==null");
continue;
};
console.dump({sentTo,sentBy});
if(sentBy.id==user.id){
ret["pendingFriends"][sentTo.id]=sentTo;
} else if ( sentTo.id==user.id ) {
ret["friendingPends"][sentBy.id]=sentBy;
};
};
};
// given a user, load all of his private cells. We do not store
// the user objects, because only friends will be in your private cells.
async function loadPrivateCells(user, ret) {
const privateCellQ = new Parse.Query('PrivateCell');
privateCellQ.equalTo("owner", user);
privateCellQ.greaterThan("updatedAt", new Date(lastLoadTime));
const privateCells = await findFully(privateCellQ);
for(var i=0;i<privateCells.length;i++) {
const cell = privateCells[i];
ret.objects[cell.id]=cell;
ret.privateCells[cell.id]=cell;
if(ret.memberMap[cell.id]==null)
ret.memberMap[cell.id]={};
const map = ret.memberMap[cell.id];
const memberQ = cell.relation("members").query();
const members = await findFully(memberQ);
for(var j=0;j<members.length;j++){
const member=members[j];
map[member.id]=1;
ret.objects[member.id]=member;
};
};
//});
}
// we use objects as maps to weed out duplicate objects and cells.
// when we are done, we use this function to replace the object
// with an array of objects. we don't need to send the keys, since
// they already exist within the objects.
function objToValueList(k,ret){
const objs = [];
for( var id in ret[k] )
objs.push(ret[k][id]);
ret[k]=objs;
ret.counts[k]=objs.length;
};
// convert the objects which have been used to accumulate key lists
// to arrays of objectIds. k is the name of the list we are working
// on. ret[k] is the list itself.
function objToKeyList(k,ret) {
const objs = [];
for( var id in ret[k] ) {
objs.push(id);
};
ret[k]=objs;
ret.counts[k]=objs.length;
};
async function checkUserConsent(user){
const query = new Parse.Query("PrivacyPolicy");
query.descending("createdAt");
query.limit(1);
const res = await query.find();
if(res.length==0) {
return true;
};
const policy=res[0];
console.dump(policy);
console.log(policy);
const userConsent=user.get("lastConsent");
return userConsent!=null && userConsent.id == policy.id;
};
async function loadAlerts(user,ret) {
const q1 = new Parse.Query("Alert");
q1.equalTo("owner", user);
const q2 = new Parse.Query("Response");
q2.equalTo("owner", user);
const q3 = new Parse.Query("Alert");
q3.matchesKeyInQuery("objectId", "alert", q2);
const q = Parse.Query.or(q1,q3);
const list = await q.find();
var time = new Date().getTime();
time -= 1000*86400;
time=Math.max(lastLoadTime, time);
q.greaterThan("updatedAt",time);
for(var i=0;i<list.length;i++) {
const item=list[i];
ret.alerts[item.id]=1;
ret.objects[item.id]=item;
};
}
async function doGetUserData(user) {
if(!user)
return {fatal: 'not logged in!' };
const ret = {
owner: {},
privateCells: {},
friends: {},
alerts: {},
objects: {},
ownedCells: {},
joinedCells: {},
spamUsers: {},
userSpams: {},
pendingFriends: {},
friendingPends: {},
memberMap: {},
loadTime: lastLoadTime,
counts: {callCount: callCount++},
};
{
user.fetch();
ret.owner=user.id;
const memberIds={};
ret.objects[user.id]=user;
console.log("loadFriends");
await loadFriends(user,ret);
console.log("loadPrivateCells");
await loadPrivateCells(user,ret,memberIds);
console.log("loadPublicCells");
await loadPublicCells(user,ret,memberIds);
console.log("loadPendingFriends");
await loadPendingFriends(user,ret);
console.log("loadUserSpams");
await loadUserSpams(user,ret);
console.log("loadSpamUsers");
await loadSpamUsers(user,ret);
console.log("loadAlerts");
await loadAlerts(user,ret);
const memberList=[];
for( var id in memberIds ) {
console.log(ret.objects[id]);
memberList.push(id);
};
console.log("loadMembers");
await loadMembers(memberList,ret);
}
for(var cell in ret.memberMap) {
var map = ret.memberMap[cell];
var list = [];
ret.memberMap[cell]=list;
for(var member in map) {
list.push(member);
};
}
delete ret.objects[user.id];
[
'friends', "friendingPends", 'pendingFriends',
'privateCells', 'ownedCells', 'joinedCells',
'userSpams', 'spamUsers', "alerts"
].forEach((k)=>{
objToKeyList(k,ret);
});
objToValueList('objects',ret);
delete ret.counts;
return ret;
}
async function getUserData(req) {
try {
var nextLoadTime=new Date().getTime();
const user = req.user;
console.log(user);
lastLoadTime = req.params.lastLoadTime;
if(lastLoadTime==null)
lastLoadTime=0;
lastLoadTime = new Date(lastLoadTime);
const ret = await doGetUserData(user);
ret.loadTime=nextLoadTime;
return ret;
} catch ( err ) {
console.log(err);
try {
console.log(err.stack());
} catch ( xxx ) {
console.log(err);
};
throw (`error getting data: ${err}`);
};
};
Parse.Cloud.define("getUserData", getUserData);
可以很容易地完成类似的操作来为您获取数据。像这个解决方案一样，它不太可能完全漂亮，但它可能会起作用。
我正在使用 Back4app。
我的个人资料class 架构有 4 个包含图片的文件列。 所以当我检索一个对象时，我必须为每个文件发出 HTTP 请求 URL 并像这样获取字节数据。
const data = await Parse.Cloud.httpRequest({url:profilePhoto.url()});
return data.buffer.toString('base64');
但是对于所有四个文件，我必须向服务器发出 4 个 HTTP 请求。 无论如何做一个批处理 HTTP 请求，这样我只需 1 个请求就可以获得所有 4 个文件的数据？ 我的主要目标是尽可能减少对服务器的请求。
在 Parse Server 中没有通过一个请求检索多个文件的现成方法。
您可以实现自己的 Parse Cloud Code 功能来检索多个文件，但您必须手动将它们组合到服务器端并在客户端分离它们。
作为起点，您可以查看像 multistream 这样的包，它们允许您将多个文件流合并为一个文件流以获得一些灵感。
您也许可以做一些类似于我在云代码中所做的事情。
我不得不在我的应用程序开始时加载一堆信息，需要多次往返服务器。
所以我写了一个叫做 getUserData() 的函数。
这会执行许多不相关的查询，并将所有结果压缩到一个大对象中。然后我 return 来自函数的对象。
这是整个函数：
console.log("startig getUserData");
var callCount = 0;
var lastLoadTime=0;
// Given a user, load all friends. Save the objects to ret.objects,
// and save the objectIds to ret.friends
//
// Note: we always load the exhaustive friend list, because
// otherwise, we would have no way of recognizing
// removed friendships.
//
async function loadFriends(user, ret) {
const friendQuery = user.relation("friends").query();
const friends = await findFully(friendQuery);
for(var i=0;i<friends.length;i++){
ret.friends[friends[i].id]=1;
ret.objects[friends[i].id]=friends[i];
};
}
// Given a user, load all owned cells. Save the objects to ret.owned,
// and save their objectIds to ret.ownedCells.
//
// Also, save the ids of members, which we will use to flesh out ret.objects with
// the objects who are not friends, but share a cell with the current user.
async function loadPublicCells(user, ret, memberIds) {
const ownedCellQ = new Parse.Query('PublicCell');
ownedCellQ.equalTo('owner',user);
const joinedCellQ = new Parse.Query('PublicCell');
joinedCellQ.equalTo('members',user);
const publicCellQ = Parse.Query.or(ownedCellQ,joinedCellQ);
publicCellQ.greaterThan("updatedAt",new Date(lastLoadTime));
const publicCells=await findFully(publicCellQ);
for(var i=0;i<publicCells.length;i++) {
const cell = publicCells[i];
ret.ownedCells[cell.id]=cell;
const owner = cell.get("owner");
if(owner==null)
continue;
ret.objects[cell.id]=cell;
if(owner.id === user.id) {
ret.ownedCells[cell.id]=1;
} else {
ret.joinedCells[cell.id]=1;
};
const memberQ = cell.relation("members").query();
const members = await findFully(memberQ);
if(ret.memberMap[cell.id]==null)
ret.memberMap[cell.id]={};
const map = ret.memberMap[cell.id];
for(var j=0;j<members.length;j++){
const member=members[j];
map[member.id]=1;
ret.objects[member.id]=member;
};
};
};
// given a list of all members of all cells, load those objects and store
// them in ret.objects. We do not have to record which cells they belong
// to, because that information is in ret.memberMap
async function loadMembers(memberIds, ret) {
const memberQ = new Parse.Query(Parse.User);
var partIds;
while(memberIds.length){
partIds = memberIds.splice(0,100);
memberQ.containedIn('objectId',partIds);
const part = await findFully(memberQ);
for(var i=0;i<part.length;i++) {
ret.objects[part[i].id]=part[i];
}
};
};
// given a user, save all of the objectIds of people who have annoyed him with
// spam. We save only the ids, they don't go on ret.objects, because we only
// need to filter them out of things. The objectIds are sufficient.
//
// We always send all spam objects, otherwise we would not recognize deletions
async function loadUserSpams(user, ret) {
const userSpamsQ = new Parse.Query("_User");
userSpamsQ.equalTo("spamUsers",user);
userSpamsQ.greaterThan("updatedAt", new Date(lastLoadTime));
const userSpams = await findFully(userSpamsQ);
for(var i=0;i<userSpams.length;i++){
ret.userSpams[userSpams[i].id]=1;
};
};
// given a user, save all of the objectIds of people who have been annoyed *BY*
// him with spam. We save only the ids, they don't go on ret.objects, because we
// only need to filter them out of things. The objectIds are sufficient.
//
// We always send all spam objects, otherwise we would not recognize deletions
async function loadSpamUsers(user, ret) {
const spamUserR = user.relation('spamUsers');
const spamUserQ = spamUserR.query();
spamUserQ.greaterThan("updatedAt", new Date(lastLoadTime));
const spamUsers = await findFully(spamUserQ);
for(var i=0;i<spamUsers.length;i++){
ret.spamUsers[spamUsers[i].id]=1;
};
};
// given a user, save all of the objectIds of people to whom he has sent a
// friend request which is still pending. We save only the ids, they don't go
// on ret.objects, because we only need to filter them out of things. The
// objectIds are sufficient.
async function loadPendingFriends(user, ret) {
const request1Q = new Parse.Query('Request');
request1Q.equalTo("owner",user);
const request2Q = new Parse.Query('Request');
request2Q.equalTo("sentTo",user);
const requestQ = Parse.Query.or(request1Q,request2Q);
requestQ.equalTo("status",'PENDING');
const requests = await findFully(requestQ);
for(var i=0;i<requests.length;i++){
const request = requests[i];
const sentBy = request.get("owner");
if(sentBy==null){
console.warn("sentBy==null");
continue;
};
const sentTo = request.get("sentTo");
if(sentTo==null){
console.warn("sentTo==null");
continue;
};
console.dump({sentTo,sentBy});
if(sentBy.id==user.id){
ret["pendingFriends"][sentTo.id]=sentTo;
} else if ( sentTo.id==user.id ) {
ret["friendingPends"][sentBy.id]=sentBy;
};
};
};
// given a user, load all of his private cells. We do not store
// the user objects, because only friends will be in your private cells.
async function loadPrivateCells(user, ret) {
const privateCellQ = new Parse.Query('PrivateCell');
privateCellQ.equalTo("owner", user);
privateCellQ.greaterThan("updatedAt", new Date(lastLoadTime));
const privateCells = await findFully(privateCellQ);
for(var i=0;i<privateCells.length;i++) {
const cell = privateCells[i];
ret.objects[cell.id]=cell;
ret.privateCells[cell.id]=cell;
if(ret.memberMap[cell.id]==null)
ret.memberMap[cell.id]={};
const map = ret.memberMap[cell.id];
const memberQ = cell.relation("members").query();
const members = await findFully(memberQ);
for(var j=0;j<members.length;j++){
const member=members[j];
map[member.id]=1;
ret.objects[member.id]=member;
};
};
//});
}
// we use objects as maps to weed out duplicate objects and cells.
// when we are done, we use this function to replace the object
// with an array of objects. we don't need to send the keys, since
// they already exist within the objects.
function objToValueList(k,ret){
const objs = [];
for( var id in ret[k] )
objs.push(ret[k][id]);
ret[k]=objs;
ret.counts[k]=objs.length;
};
// convert the objects which have been used to accumulate key lists
// to arrays of objectIds. k is the name of the list we are working
// on. ret[k] is the list itself.
function objToKeyList(k,ret) {
const objs = [];
for( var id in ret[k] ) {
objs.push(id);
};
ret[k]=objs;
ret.counts[k]=objs.length;
};
async function checkUserConsent(user){
const query = new Parse.Query("PrivacyPolicy");
query.descending("createdAt");
query.limit(1);
const res = await query.find();
if(res.length==0) {
return true;
};
const policy=res[0];
console.dump(policy);
console.log(policy);
const userConsent=user.get("lastConsent");
return userConsent!=null && userConsent.id == policy.id;
};
async function loadAlerts(user,ret) {
const q1 = new Parse.Query("Alert");
q1.equalTo("owner", user);
const q2 = new Parse.Query("Response");
q2.equalTo("owner", user);
const q3 = new Parse.Query("Alert");
q3.matchesKeyInQuery("objectId", "alert", q2);
const q = Parse.Query.or(q1,q3);
const list = await q.find();
var time = new Date().getTime();
time -= 1000*86400;
time=Math.max(lastLoadTime, time);
q.greaterThan("updatedAt",time);
for(var i=0;i<list.length;i++) {
const item=list[i];
ret.alerts[item.id]=1;
ret.objects[item.id]=item;
};
}
async function doGetUserData(user) {
if(!user)
return {fatal: 'not logged in!' };
const ret = {
owner: {},
privateCells: {},
friends: {},
alerts: {},
objects: {},
ownedCells: {},
joinedCells: {},
spamUsers: {},
userSpams: {},
pendingFriends: {},
friendingPends: {},
memberMap: {},
loadTime: lastLoadTime,
counts: {callCount: callCount++},
};
{
user.fetch();
ret.owner=user.id;
const memberIds={};
ret.objects[user.id]=user;
console.log("loadFriends");
await loadFriends(user,ret);
console.log("loadPrivateCells");
await loadPrivateCells(user,ret,memberIds);
console.log("loadPublicCells");
await loadPublicCells(user,ret,memberIds);
console.log("loadPendingFriends");
await loadPendingFriends(user,ret);
console.log("loadUserSpams");
await loadUserSpams(user,ret);
console.log("loadSpamUsers");
await loadSpamUsers(user,ret);
console.log("loadAlerts");
await loadAlerts(user,ret);
const memberList=[];
for( var id in memberIds ) {
console.log(ret.objects[id]);
memberList.push(id);
};
console.log("loadMembers");
await loadMembers(memberList,ret);
}
for(var cell in ret.memberMap) {
var map = ret.memberMap[cell];
var list = [];
ret.memberMap[cell]=list;
for(var member in map) {
list.push(member);
};
}
delete ret.objects[user.id];
[
'friends', "friendingPends", 'pendingFriends',
'privateCells', 'ownedCells', 'joinedCells',
'userSpams', 'spamUsers', "alerts"
].forEach((k)=>{
objToKeyList(k,ret);
});
objToValueList('objects',ret);
delete ret.counts;
return ret;
}
async function getUserData(req) {
try {
var nextLoadTime=new Date().getTime();
const user = req.user;
console.log(user);
lastLoadTime = req.params.lastLoadTime;
if(lastLoadTime==null)
lastLoadTime=0;
lastLoadTime = new Date(lastLoadTime);
const ret = await doGetUserData(user);
ret.loadTime=nextLoadTime;
return ret;
} catch ( err ) {
console.log(err);
try {
console.log(err.stack());
} catch ( xxx ) {
console.log(err);
};
throw (`error getting data: ${err}`);
};
};
Parse.Cloud.define("getUserData", getUserData);
可以很容易地完成类似的操作来为您获取数据。像这个解决方案一样，它不太可能完全漂亮，但它可能会起作用。