I'm trying to get users from database and then loop throug each user and get their images. However when I try to assign images array to user.images property nothing happens. I still get only users with empty images array.
Currently my code is the following:
user.getAll().then(result =>{
const userCollection = result[0];
for(let i=0; i < userCollection.length; i++){
userCollection[i].images = [{}];
image.getImagesByUserId(userCollection[i].Id).then(res =>{
userCollection[i].images = res[0];
}).catch(err =>{
console.log(err);
res.status(400).json(err);
})
}
res.json(userCollection);
})
.catch(err =>{
console.log(err);
res.status(400).json(err);
});
Why I can't assign images array to it's property?
It looks to me like you need to run your res.json(userCollection) from inside the callback.
This will of course mean you need to rename your res variable in the callback
This is assuming you are somehow using res.json(userCollection) to export the information. Which I am inferring based on the fact I don’t see res defined anywhere
May be a silly question, but are you assigning it? I only see
userCollection[i].images = [{}];
above and never see:
userCollection[i].images = res;
assignment once you grab the images.
The problem is that getImagesByUserId() is asynchronous so by the time you get to the assignment, you've already sent the response.
The order of events you have currently is:
Assign an empty image list to all the users
Queue up a load of database requests
Send the response (res.json())
Reassign the images for all the users once the database results come back.
The easy fix is to look at Promise.all() and aggregate the results when they all come back.
However, this isn't the most efficient way to deal with SQL databases, I would suggest you restructure your query so that you get all the images for all the users in 1 trip to the database and then format the response based on those results.
Say you have an image table and a user table, something like:
SELECT image_name, user_id
FROM image
then replace your loop in your js with:
getImagesForUsers().then(result => {
//create your response from the rows
res.json(response);
});
Related
I am developing a web app on Firebase/firestore, in which users can sign in and write their own posts. The data are stored in the following way:
-User information are stored as under collection('user').doc('uid').
-Information about posts the user has written are stored in collection('post').doc('postid'), and the doc has 'userinfo' and 'uid' fields. The 'userinfo' field contains exact copy of what is stored in 'uid' doc, just in object format.
Here are the operations that I want to do:
When the user changes the data, the changes are reflected in the document.
Look for the all the posts that the user has written based on 'uid' data, and then update userinfo in those data.
The last part is tricky for me. The Firebase documentations cover situations where the references are pretty much static, i.e. you know the exact path to write/update. What I am trying to do is look for a set of documents that is not necessarily static, and then update each of them.
Here is the code I wrote for this effort. The first part works without any problem. Of course, the second part doesn't work. :) What would be the code to do the do the second part?
const update = () => {
//This part is for updating user information. This works without any problem.
firebase.firestore().collection('user').doc(user.uid).update({
username: username1,
nickname: nickname1,
intro: intro1
})
.then(()=>{
//This part is for updating all of the document that the user has written based on 'uid' value. This doesn't work.
//Below code is probably way off, but it shows where I am going and what I am trying to do.
firebase.firestore().collection('post').where('uid','==',user.uid).get()
.then((querysnapshot)=>{
querysnapshot.forEach((doc)=>{
let ref=firebase.firestore().collection('post').doc(doc.id);
ref.update({
userinfo: {nickname:nickname1,username:username1,intro:intro1}
})
})
})
}).then(()=>{
alert("Successfully updated!");
window.location.href='/'+username1;
}).catch((error)=>{
alert("Error!");
})
}
Thanks a lot in advance!
What's the error that you get running this code? It seems on the right track for me.
But despite that, here are some suggestions to deal with this kind of update:
Don't do the second part on the client side, do it on the server side with a Firestore Trigger (create a onUpdate trigger in the user collection in your case): https://firebase.google.com/docs/functions/firestore-events.
The problem of doing in the client side, is because if the user closes the page/browser or the site goes offline in the middle of the update, you will have inconsistent data.
You don't need to recreate the DocumentReference after getting the query result, the docs returned already have a .ref that you can call .ref.update() directly.
EDIT: If you want to keep your original code (updating on client side), the problem of the navigation occurring before all the updates to conclude is because ref.update() returns a promise.
So the update queue is asynchronous being performed on database when the client navigates away.
To solve this, I would use a Promise.all() to wait all updates being completed.
firebase.firestore().collection('post').where('uid','==',user.uid).get()
.then((querysnapshot)=>{
const promises = [];
querysnapshot.forEach((doc)=>{
promises.push(doc.ref.update({
userinfo: {nickname:nickname1,username:username1,intro:intro1}
});
});
Promise.all(promises).then(()=>{window.location.href='/'+username1;});
});
Or using the await syntax (I think it's easier to maintain and understand):
const querysnapshot = await firebase.firestore().collection('post').where('uid','==',user.uid).get();
const promises = [];
querysnapshot.forEach((doc)=>{
promises.push(doc.ref.update({
userinfo: {nickname:nickname1,username:username1,intro:intro1}
});
});
await Promise.all(promises);
window.location.href='/'+username1;
I'm trying to get a list of all of my uploaded images (array of images) from a db using express. However, when I make a request to get them, I get a weird square, or I get a lot of weird characters.
I've tried streaming the array as a whole, I've tried sending it using res.end/res.write one by one by looping through the array, I've tried streaming and piping, but so far, nothing.
//gets data from db
let getAllPhotos = await ListingPhoto.find({
"listing._id": listingId
}).then((images) => {
return images.map(item => {
//want to send response here as we go
return item.file;
})
})
//or send all the files(images) that's in getAllphotos down here
I want to be able to see all of the photos in the response
I have a page with a form that gives a user the option to filter a list of objects (programs) by selecting options. For example, they could select the option architecture to show only the programs which contain that subject. An AJAX-request is sent to the server, which then returns the results. So far, everything works.
My problem: in some browser when someone clicks to go to another page and then goes back to the page where the form is, the results are reset, although the form selection(s) are still visible. In Chrome this is a problem, whereas in Firefox this does not happen. On this page you can see a live example.
My JavaScript AJAX post-request looks like this:
let sendQuery = () => {
let programsList = document.getElementById('programs-list');
axios.post('/programs/getByFilter', filter )
.then(function (response) {
programsList.innerHTML = response.data;
})
.catch(function (error) {
console.log(error);
});
}
And then in PHP (I use Symfony):
/**
* #Route("/getByFilter", name="program_get_by_filter")
*/
public function returnProgramsByFilter(Request $request, SearchHelper $searchHelper)
{
$jsonFilter = $request->getContent();
$filter = json_decode($jsonFilter, true);
// the query is done here.
$programs = $searchHelper->findByFilter($filter);
return $this->render('program/programs_ajax.html.twig', [
'programs' => $programs ]);
}
Now I have looked for similar questions and found this one and this one, but I haven't been able to solve the problem. Initially I tried to send the request as a GET-request instead of a POST-request, but the data I send is JSON and I did not manage to make it work. I am not really sure if that has to do with the JSON or not. My understanding of JS is really poor. Then I tried with a session variable like so:
$jsonFilter = $request->getContent();
$filter = json_decode($jsonFilter, true);
$session->set('filter', $filter);
And then:
if($session->has('filter')){
$programs = $searchHelper->findByFilter($session->get('filter'));
} else {
$programs = $programRepository->findAll();
}
This does not really work either because the original options will be overwritten when going back and making a new selection. Also, with my JS I show the current filters that are being used and the number of results. That's gone too.
Is there a JS solution or should I try to fix this in PHP?
Update:
I have been able to set filter as a cookie every time an ajax call is made by making it a string with JSON.stringify(filter) and then I get it and use it with:
// Getting the cookie, parsing it and running the query.
var filterCookie = getCookie('filter');
if (filterCookie) {
var objectCookieFilter = JSON.parse(filterCookie);
let programsList = document.getElementById('programs-list');
axios
.post('/programs/getByFilter', objectCookieFilter )
.then(function (response) {
programsList.innerHTML = response.data;
})
.catch(function (error) {
console.log(error);
});
}
This will re-run the last query that was set in the cookie. The problem that remains though is that all the filter-badges are set on a change event of the checkboxes and I cannot figure out how to show them based on the cookie (or perhaps some other way?)
i have a Problem!
When two users playing a game and they click very near at the same time, all two users get what only the 2nd user must get.
Is it possible to make an array by his userid or something?
I also have for anti spam like that
anti_spam[socket.request.session.passport.user.id]
But thats a json
If i try the same or array, i get error SyntaxError: Unexpected token [
How can i make sure, that each user get only his own items and not items from another user when opening at the same time?
I use sockets, here is a unique userid socket.request.session.passport.user.id
This is the array
var WinItem = [];
And if two users start like milliseconds same time, than the second overwrite the first...
! CODE NOT TESTED!
Wait wait wait wait...
So I only know ws (Node.js) but there you first get a onConnection event.
In that function you add a UID to the connection element. Then if you receive a message from the client you should have you're connection object and therefore an UID. You now can store the won item in the connection object (if you want) maybe like so:
ws.onConnection = con => {
con.UID = generateUID();
con.inventory = [];
con.onMessage = msg => {
[..STUFF/CODE/YAY...]
con.inventory.push(item);
con.send("You've won wooohoo");
});
});
Did you mean something like this??
Otherwise please be more specific about what you want.
(You can also store the stuff somewhere else together with the UID but that would add quiet some code)
I have a list of known keys in my Firebase database
-Ke1uhoT3gpHR_VsehIv
-Ke8qAECkZC9ygGW3dEJ
-Ke8qMU7OEfUnuXSlhhl
Rather than looping through each of these keys to fetch a snapshot of their respective object, how can I query for each of these keys in one single, unified request? Does Firebase provide this?
I've discovered the Promise.all() function which looks promising (no pun intended I swear) but I'm not sure how to implement it using the standard way of fetching firebase data like so
var userId = firebase.auth().currentUser.uid;
return firebase.database().ref('/users/' + userId).once('value').then(function(snapshot) {
var username = snapshot.val().username;
});
Thanks for any help!
As David's comment suggested: if the items are in some way related, you may be able to built a query to get them all.
Otherwise this would do the trick:
var keys = [
"-Ke1uhoT3gpHR_VsehIv",
"-Ke8qAECkZC9ygGW3dEJ",
"-Ke8qMU7OEfUnuXSlhhl"
];
var promises = keys.map(function(key) {
return firebase.database().ref("/items/").child(key).once("value");
});
Promise.all(promises).then(function(snapshots) {
snapshots.forEach(function(snapshot) {
console.log(snapshot.key+": "+snapshot.val());
});
});
Note that retrieving each item with a separate request is not as slow as you may think, since the requests are all sent over a single connection. For a longer explanation of that, see Speed up fetching posts for my social network app by using query instead of observing a single event repeatedly.