I have an app where user can vote on a photo, then move on to the next. I need to know the most efficient strategy to keep track of the photos a user has already voted on, so he will not be presented the same photo twice.
My current strategy is to keep in each user profile an array with all already voted photos ids. I then fetch new photos and make sure their ids don't match any id in the array.
I don't think this is the proper strategy as arrays are supposed to contain a limited number of items.... and in this case a user could have viewed A LOT of images.
I don't think neither that it would be appropriate to create a class with an entry for each vote.
There are several options available in Parse.com documentation about "relations" but i'm really not sure the one to choose to:
1) Keep track photos seen by user
2) Fetch new photos excluding those
If you know the best way to do this, please advise. I'm on iOS swift / but this problem is language agnostic.
I finally established relations between photos and users as suggested:
var query = PFQuery(className:"Photos")
query.getObjectInBackgroundWithId(objectId) {
(photoEntry: PFObject!, error: NSError!) -> Void in
if error != nil {
NSLog("%#", error)
} else {
var relation = photoEntry.relationForKey("UsersThatVoted")
relation.addObject(PFUser.currentUser())
photoEntry.saveInBackgroundWithBlock {
//Rest of the query
where "UsersThatVoted" is the relation field in 'Photos' class, that links to Parse default Users class. This is triggered each time user has voted on a photo.
Then, it is very easy to make a regular query to exclude those photos with relation to current user, so he don't see twice a same photo:
query.whereKey("UsersThatVoted", notEqualTo: PFObject(withoutDataWithClassName:"_User", objectId:me.objectId))
Where me is current user. You just add this line to a regular query (to 'Photos' in my case), you don't even need to do a second inner query.
Related
My situation is this: I have multiple components in my view that ultimately depend on the same data, but in some cases the view state is derived from the data. How do I make sure my whole view stays in sync when the underlying data changes? I'll illustrate with an example using everyone's favorite Star Wars API.
First, I show a list of all the films, with a query like this:
# ALL_FILMS
query {
allFilms {
id
title
releaseDate
}
}
Next, I want a separate component in the UI to highlight the most recent film. There's no query for that, so I'll implement it with a client-side resolver. The query would be:
# MOST_RECENT_FILM
query {
mostRecentFilm #client {
id
title
}
}
And the resolver:
function mostRecentFilmResolver(parent, variables, context) {
return context.client.query({ query: ALL_FILMS }).then(result => {
// Omitting the implementation here since it's not relevant
return deriveMostRecentFilm(result.data);
})
}
Now, where it gets interesting is when SWAPI gets around to adding The Last Jedi and The Rise of Skywalker to its film list. We can suppose I'm polling on the list so that it gets periodically refetched. That's great, now my list UI is up to date. But my "most recent film" UI isn't aware that anything has changed — it's still stuck in 2015 showing The Force Awakens, even though the user can clearly see there are newer films.
Maybe I'm spoiled; I come from the world of MobX where stuff like this Just Works™. But this doesn't feel like an uncommon problem. Is there a best practice in the realm of Apollo/GraphQL for keeping things in sync? Am I approaching this problem in entirely the wrong way?
A few ideas I've had:
My "most recent film" query could also poll periodically. But you don't want to poll too often; after all, Star Wars films only come out every other year or so. (Thanks, Disney!) And depending on how the polling intervals overlap there will still be a big window where things are out of sync.
Instead putting the deriveMostRecentFilm logic in a resolver, just put it in the component and share the ALL_FILMS query between components. That would work, but that's basically answering "How do I get this to work in Apollo?" with "Don't use Apollo."
Some complicated system of keeping track of the dependencies between queries and chaining refreshes based on that. (I'm not keen to invent this if I can avoid it!)
In Apollo observables are (in components) over queried values (cached data 'slots') but your mostRecentFilm is not an observable, is not based on cached values (they are cached) but on one time fired query result (updated on demand).
You're only missing an 'updating connection', f.e. like this:
# ALL_FILMS
query {
allFilms {
id
title
releaseDate
isMostRecentFilm #client
}
}
Use isMostRecentFilm local resolver to update mostRecentFilm value in cache.
Any query (useQuery) related to mostRecentFilm #client will be updated automatically. All without additional queries, polling etc. - Just Works? (not tested, it should work) ;)
My app requires facebook login, so it is supposed I have all facebook ids from my users. What I want to o in cloud code is a function that given a facebook id (a string), returns the user (or null if no exists). The problem I see is that it seems the facebook id is inside a json structure in the authData column, but I have no idea how to create a query to access to that information. I found this: https://www.parse.com/questions/how-to-get-the-facebook-id-of-an-pfuser-from-a-pfquery-in-ios but no idea about how to use it.
Can you help me with the function I want to create? Thanks in advance.
My comment on Eric's answer expresses my concerns around security, but the cloud-code BeforeSave() function to address my concerns really isn't difficult... for simple use-cases:
Parse.Cloud.beforeSave("MyObject", function(request, response) {
request.object.set("owner_facebook_id", request.user.get("authData").facebook.id);
response.success();
});
In your case, MyObject is the user class, and as long as no users can modify properties on another user object, than this will work pretty well.
However, for the app I was working on, we allowed any user to "like" an object, which incremented a "number_of_likes" property on the object. At that point, this became more tricky, because the user making that request was not, in fact, the owner of the object, so their Facebook_id properties wouldn't have matched.
The work-around was to try and detect whether or not the object had previously existed, and then just make sure the Facebook_id never changed after it was originally created.
We had to access the ORIGINAL object and make sure the newly-saving object had the same Facebook id... it was not exactly trivial, and that lookup actually counts against your request limit. This, combined with a few more edge-cases, caused us to ultimately abandon Parse for that project.
The problem with using authData is that you need a valid active session of that user (or use your master key) to access the data.
If you don't already have a large amount of users, I would recommend creating a new column in your User class that stores the Facebook ID so you can query for it later. That way, you could do something like:
var query = new Parse.Query("User");
query.equalTo("facebookId", request.params.facebookId);
query.find({
success: function(results) {
// do something with the resulting user at results[0], if found
},
error: function() {
response.error("lookup failed");
}
});
In my app I am using the parse framework. The basic breakdown for my current situation is that I have users who can like photo albums or photos individually. If a user likes an individual photo I want to place that photo into a new album specific to that user. That way I can easily retrieve an album filled with any given users liked photos.
I want the logic to be as simple and straight forward as possible and I have come to a conclusion, but I need another opinion to see if that's the best way to do it.
I plan to have a pointer to a 'liked photos' album as an object that is accessible on any user object. That way if a user likes a photo I can set the photoAlbumOwner as that album object on a users profile. Then for future retrieval I just need to find all photos that are associated with that album.
Every other option I have thought about requires me to fetch/search data to find the album for a specific user every time they like a photo. That would not be desirable because it's just extra data needing to be downloaded, which leads to more time.
Is this the best way to go about this or is there another option that would be more simple?
I would create an array field called likedPhotos in the _User class and then just add an reference to this liked photo.
Javascript code:
function likePhoto(photo) {
var user = Parse.User.current();
user.add('likedPhotos', photo);
user.save();
}
I have a form that I have users fill out and then it gets e-mailed to me.
I am trying to get an example of how I would create an ID (based on my own conventions) that I can use to keep track of responses (and send back to the user so they can reference it later).
This is the convention I am striving for:
[YEAR]-[SERVICE CODE]-[DATE(MMDD)]-[TIME]
For example: "2012-ABC-0204-1344". I figured to add the TIME convention in the instance that two different users pick the same service on the same date rather than try to figure out how to only apply it IF two users picked the same service on the same date.
So, the scenario is that after the user goes through my wizards inputting their information and then click "Submit" that this unique ID would be created and attached to the model. Maybe something like #Model.UniqueID so that in an e-mail response I send to the user it shows up and says "Reference this ID for any future communication".
Thanks for any advice/help/examples.
In your post action
[HttpPost]
public ActionResult Create(YourModel model)
{
model.UniqueId = GenerateUniqueId(serviceCode);
}
public string GenerateUniqueId(string serviceCode)
{
return string.Format("{0}-{1}-{2}", DateTime.Now.Year, serviceCode, Guid.NewGuid().ToString().Replace("-",""); //remove dashes so its fits into your convention
}
but this seems as I'm missing part of your question. If you really want unique, use a Guid. This is what we've used in the past to give to customers - a guid or a portion of one. IF you use a portion of one ensure you have logic to handle a duplicate key. You don't need to worry about this though if using a full guid. If the idea is just to give to a customer then ignore the rest of the data and just use a guid, since it can easily be looked up in the database.
So, I'm not quite sure how I should structure this in CakePHP to work correctly in the proper MVC form.
Let's, for argument sake, say I have the following data structure which are related in various ways:
Team
Task
Equipment
This is generally how sites are and is quite easy to structure and make in Cake. For example, I would have the a model, controller and view for each item set.
My problem (and I'm sure countless others have had it and already solved it) is that I have a level above the item sets. So, for example:
Department
Team
Task
Equipment
Department
Team
Task
Equipment
Department
Team
Task
Equipment
In my site, I need the ability for someone to view the site at an individual group level as well as move to view it all together (ie, ignore the groups).
So, I have models, views and controls for Depart, Team, Task and Equipment.
How do I structure my site so that from the Department view, someone can select a Department then move around the site to the different views for Team/Task/Equipment showing only those that belong to that particular Department.
In this same format, is there a way to also move around ignoring the department associations?
Hopefully the following example URLs clarifies anything that was unclear:
// View items while disregarding which group-set record they belong to
http://www.example.com/Team/action/id
http://www.example.com/Task/action/id
http://www.example.com/Equipment/action/id
http://www.example.com/Departments
// View items as if only those associated with the selected group-set record exist
http://www.example.com/Department/HR/Team/action/id
http://www.example.com/Department/HR/Task/action/id
http://www.example.com/Department/HR/Equipment/action/id
Can I get the controllers to function in this manner? Is there someone to read so I can figure this out?
Thanks to those that read all this :)
I think I know what you're trying to do. Correct me if I'm wrong:
I built a project manager for myself in which I wanted the URLs to be more logical, so instead of using something like
http://domain.com/project/milestones/add/MyProjectName I could use
http://domain.com/project/MyProjectName/milestones/add
I added a custom route to the end (!important) of my routes so that it catches anything that's not already a route and treats it as a "variable route".
Router::connect('/project/:project/:controller/:action/*', array(), array('project' => '[a-zA-Z0-9\-]+'));
Whatever route you put means that you can't already (or ever) have a controller by that name, for that reason I consider it a good practice to use a singular word instead of a plural. (I have a Projects Controller, so I use "project" to avoid conflicting with it.)
Now, to access the :project parameter anywhere in my app, I use this function in my AppController:
function __currentProject(){
// Finding the current Project's Info
if(isset($this->params['project'])){
App::import('Model', 'Project');
$projectNames = new Project;
$projectNames->contain();
$projectInfo = $projectNames->find('first', array('conditions' => array('Project.slug' => $this->params['project'])));
$project_id = $projectInfo['Project']['id'];
$this->set('project_name_for_layout', $projectInfo['Project']['name']);
return $project_id;
}
}
And I utilize it in my other controllers:
function overview(){
$this->layout = 'project';
// Getting currentProject id from App Controller
$project_id = parent::__currentProject();
// Finding out what time it is and performing queries based on time.
$nowStamp = time();
$nowDate = date('Y-m-d H:i:s' , $nowStamp);
$twoWeeksFromNow = $nowDate + 1209600;
$lateMilestones = $this->Project->Milestone->find('all', array('conditions'=>array('Milestone.project_id' => $project_id, 'Milestone.complete'=> 0, 'Milestone.duedate <'=> $nowDate)));
$this->set(compact('lateMilestones'));
$currentProject = $this->Project->find('all', array('conditions'=>array('Project.slug' => $this->params['project'])));
$this->set(compact('currentProject'));
}
For your project you can try using a route like this at the end of your routes.php file:
Router::connect('/:groupname/:controller/:action/*', array(), array('groupname' => '[a-zA-Z0-9\-]+'));
// Notice I removed "/project" from the beginning. If you put the :groupname first, as I've done in the last example, then you only have one option for these custom url routes.
Then modify the other code to your needs.
If this is a public site, you may want to consider using named variables. This will allow you to define the group on the URL still, but without additional functionality requirements.
http://example.com/team/group:hr
http://example.com/team/action/group:hr/other:var
It may require custom routes too... but it should do the job.
http://book.cakephp.org/view/541/Named-parameters
http://book.cakephp.org/view/542/Defining-Routes
SESSIONS
Since web is stateless, you will need to use sessions (or cookies). The question you will need to ask yourself is how to reflect the selection (or not) of a specific department. It could be as simple as putting a drop down selection in the upper right that reflects ALL, HR, Sales, etc. When the drop down changes, it will set (or clear) the Group session variable.
As for the functionality in the controllers, you just check for the Session. If it is there, you limit the data by the select group. So you would use the same URLs, but the controller or model would manage how the data gets displayed.
// for all functionality use:
http://www.example.com/Team/action/id
http://www.example.com/Task/action/id
http://www.example.com/Equipment/action/id
You don't change the URL to accommodate for the functionality. That would be like using a different URL for every USER wanting to see their ADDRESS, PHONE NUMBER, or BILLING INFO. Where USER would be the group and ADDRESS, PHONE NUMBER< and BILLING INFO would be the item sets.
WITHOUT SESSIONS
The other option would be to put the Group filter on each page. So for example on Team/index view you would have a group drop down to filter the data. It would accomplish the same thing without having to set and clear session variables.
The conclusion is and the key thing to remember is that the functionality does not change nor does the URLs. The only thing that changes is that you will be working with filtered data sets.
Does that make sense?