How do you return a collection of a grouped dataset in a ManytoMany relationship with this scenario?
Here is a sample of what dataset I want to return
So let's take the favorites as the genres and the highlighted date is the genres name, it's also a collection as well. I want to group it based on the genres name in that collection.
My model:
Video
```
public function genres() {
return $this->belongsToMany(Genre::class);
}
```
Genre
```
public function videos() {
return $this->belongsToMany(Video::class);
}
```
I tried the following already but can't seem to get it.
```
$videos = Video::with('genres')->all();
$collection = $videos->groupBy('genres.name');
```
I want to group the dataset by the genres name knowing the genre's relationship is also a collection of genres.
Try something like:
Video::with('genres')->get()->groupBy('genres.*.name');
Or:
$videos = Video::with('genres')->all();
$collection = $videos->groupBy('genres.*.name');
Note that above is code you posted, just after replacing "genres.name" with "genres.*.name".
Just noticed the post is old, this at least works on latest Laravel.
Collections and query builders share many similar functions such as where() groupBy() and so on. It's nice syntax sugar, but it really does obscure the underlying tech.
If you call $model->videos... like a property, that's a collection (query has executed).
If you call $model->videos()... like a method, that's a query builder.
So if you want to get the job done in sql, you can do something like...
$video_query_builder = Video::with('genere');
$video_query_builder->groupBy('genere_id');
$result = $video_query_builder->get();
You can chain it all together nice and neatly as was suggested in the comments... like this:
$result = Video::with('genere')
->groupBy('genere_id')
->get();
Related
I have various parent/child relationships, drilling down a few levels. What I want to know is if its possible to do something like this:
$student = Student::find(1);
$student->bursaries()->enrolments()->courses()->where('course','LIKE','%B%');
(With the end goal of selecting the course which is like '%B%'), or if I would have to instead use the DB Query builder with joins?
Models / Relationships
Student:
public function bursaries() {
return $this->hasMany('App\StudentBursary');
}
StudentBursary:
public function enrolments() {
return $this->hasMany('App\StudentBursaryEnrolment');
}
If what you want is to query all courses, from all enrollments, from all bursaries, from a students, then, unfortunately, you are one table too many from getting by with the Has Many Through relationship, because it supports only 3 tables.
Online, you'll find packages that you can import / or answers that you can follow to provide you more though of solutions, for example:
1) How to use Laravel's hasManyThrough across 4 tables
2) https://github.com/staudenmeir/eloquent-has-many-deep
Anyhow, bellow's something you can do to achieve that with Laravel alone:
// Eager loads bursaries, enrolments and courses, but, condition only courses.
$student = Student::with(['bursaries.enrolments.courses' => function($query) {
$query->where('course','LIKE','%B%');
}])->find(1);
$enrolments = collect();
foreach($student->bursaries as $bursary) {
$enrolments = $enrolments->merge($bursary->enrolments);
}
$courses = collect();
foreach ($enrolments as $enrolment) {
$courses = $courses->merge($enrolment->courses);
}
When you do $student->bursaries() instead of $student->bursaries, it returns a query builder instead of relationship map. So to go to enrolments() from bursaries() you need to do a bursaries()->get(). It should look like this.
$student->bursaries()->get()[0]->enrolments(), added the [0] because im using get(), you can use first() to avoid the [0]
$student->bursaries()->first()->enrolments()
But I'm not sure if it will suffice your requirement or not.
I started learning Laravel and I am trying to achieve the following:
Get data from database and display specific field.
Here is my code in the controller:
public function show()
{
$students = DB::select('select * from students', [1]);
return $students;
}
Here is my route code:
Route::get('', "StudentController#show");
That all works for me and I get the following displayed:
[{"id":1,"firstname":"StudentFirstName","lastname":"StudentLastName"}]
How can I get only the "lastname" field displayed?
Thanks in advance!
DB::select('select * from students')
is a raw query that returns an array of stdClass objects, meaning you have to loop through the array and access properties:
$students[0]->lastname
You can also use the query builder to return a collection of objects:
$collection = DB::table('students')->get();
$student = $collection->first();
$student->lastname;
Lastly, using the query builder, you can use pluck or value to get just the last name. If you only have one user, you can use value to just get the first value of a field:
DB::table('students')->where('id', 1)->value('lastname');
I strongly advise you to read the Database section of the Laravel docs.
$students[0]['lastname'] will return the last name field, the [0] will get the first student in the array.
I would recommend creating a model for Students, which would make your controller something like this:
$student = Students::first(); // to get first student
$student->lastname; // get last names
If you only want the one column returned, you can use pluck()
public function show()
{
$last_names= DB::table('students')->pluck('lastname');
return $last_names;
}
This will return an array of all the students' lastname values.
If you want just one, you can access it with $last_names[0]
As a side note, your show() method usually takes a parameter to identify which student you want to show. This would most likely be the student's id.
There are several ways you can accomplish this task. Firstly, I advise you to use the model of your table (probably Students, in your case).
Thus, for example,to view this in the controller itself, you can do something like this using dd helper:
$student = Students::find(1);
dd($student->lastname);
or, using pluck method
$students = Students::all()->pluck('lastname');
foreach($students as $lastName) {
echo $lastName;
}
or, using selects
$students = DB::table('students')->select('lastname');
dd($students);
Anyway, what I want to say is that there are several ways of doing this, you just need to clarify if you want to debug the controller, display on the blade...
I hope this helps, regards!
I've got a collection of records retrieved via a relationship, and I'd like to order them by the created_at field. Is this possible in Eloquent?
Here is how I am retrieving the collection:
$skills = $employee->skills;
I'd like to order this $skills collection by their creation. I've tried $skills->orderBy('created_at', 'desc'); but the Collection class does not have an orderBy method.
I guess this problem is very simple and I'm missing something..
You can do this in two ways. Either you can orderBy your results while query, as in
$employee->skills()->orderBy('created_at', 'desc')->get();
OR
You can use sortBy and sortByDesc on your collection
The reason this is failing is that orderBy is a query method not a collection method.
If you used $skills = $employee->skills()->orderBy('created_at', 'desc')->get();, this would query the skills in the order you want.
Alternatively, if you already had a collection that you wanted to re-order, you could use the sortBy or sortByDesc methods.
You need to add the orderBy constraint on the query instead of the relationship.
For e.g,
$employees = Employee::where('salary', '>', '50000') // just an example
->with('skills') // eager loading the relationship
->orderBy('created_at', 'desc')
->get();
and then:
foreach($employees as $employee)
{
var_dump($employee->skill);
}
If you want the results to always be ordered by a field, you can specify that on the relationship:
Employee.php
public function skills() {
return $this->hasMany(Skills::class)->orderBy('created_at');
}
If you just want to order them sometimes, you can use orderBy(), but on the relationship, not the property:
$skills = $employee->skills()->orderBy('created_at')->get();
Collection has sortBy and sortByDesc
$skills = $skills->sortBy('created_at');
$skills = $skills->sortByDesc('created_at');
This Stackoverflow question askes how to order an Eloquent collection. However, I would like to propose a different solution to use instead given the example in the question. I would like to recommend to use an ordering on the query itself for performance reasons.
Like #Don't Panic proposes you can specify a default ordering on the relationship for great reusability convenience:
app/Models/Employee.php
public function skills() {
return $this->hasMany(Skills::class)->orderBy('created_at');
}
However, if you have already set an ordering on your query like we do in the code above, any additional orderings will be ignored. So that is a bummer if you want to use a different sorting in another situation. To overwrite this default ordering and re-order the query with a new ordering, one needs to use the reorder() method. For example:
// Get a Collections of Skill-models ordered by the oldest skill first.
$skills = $employee->skills()->reorder()->orderByDesc('created_at')->get();
// Same result as the previous example, but different syntax.
$skills = $employee->skills()->reorder()->oldest()->get();
// Or just give some arguments to the reorder() method directly:
$skills = $employee->skills()->reorder('created_at', 'desc')->get();
I have a one-to-many relationship, which works perfectly when using the relationship as a property on a query, but when i try to use it as a method it always return empty.
User Model
public function reports()
{
return $this->hasMany('App\Report', Report::COL_USER_ID, self::COL_ID);
}
Report Model
public function user()
{
return $this->hasOne('App\User', User::COL_ID, self::COL_USER_ID);
}
This Works
$reports = User::find($id)->reports;
This Doesn't and i need something like this
$reports = User::find($id)->reports()->orderBy(Report::COL_CREATED_AT, self::ORDER_BY_DESC);
According to the eloquent doc, "since all relationships also serve as query builders, you can add further constraints", so that should totally be retrieving the proper data, am I missing something? Thanks in advance for any help
You need to use get method to get actual results, so you should use:
$reports = User::find($id)->reports()->orderBy(Report::COL_CREATED_AT, self::ORDER_BY_DESC)->get();
instead of only:
$reports = User::find($id)->reports()->orderBy(Report::COL_CREATED_AT, self::ORDER_BY_DESC);
In your case, you only created query and haven't get any results from database. That's why you don't get any results.
And the reason why:
$reports = User::find($id)->reports;
works is because it's shortcut for:
$reports = User::find($id)->reports()->get();
If you try to use:
$reports = User::find($id)->reports();
only you won't get any results either.
I'm using laravel and eloquent.
Actually I have problems filtering results from a table based on conditions on another table's attributes.
I have 3 tables:
venue
city
here are the relationships:
a city has many locations and a location belongs to a city.
a location belongs to a venue and a venue has one location.
I have a city_id attribute on locations table, which you may figured out from relationships.
The question is simple:
how can I get those venues which belong to a specific city?
the eloquent query I expect looks like this:
$venues=Venue::with('location')->where('location.city_id',$city->getKey());
Of course that's not gonna work, but seems like this is common task and there would be an eloquent command for it.
Thanks!
A couple of options:
$venues = Venue::whereIn('location_id', Location::whereCityId($city->id)->get->lists('id'))
->get();
Or possibly using whereHas:
$venues = Venue::whereHas('location', function($query) use ($city) {
$query->whereCityId($city->id);
})->get();
It is important to remember that each eloquent query returns a collection, and hence you can use "collection methods" on the result. So as said in other answers, you need a Eager Loading which you ask for the attribute you want to sort on from another table based on your relationship and then on the result, which is a collection, you either use "sortBy" or "sortByDesc" methods.
You can look at an example below:
class Post extends Model {
// imagine timpestamp table: id, publish, delete,
// timestampable_id, timestampble_type
public function timestamp()
{
return $this->morphOne(Timestamp::class, 'timestampable');
}
}
and then in the view side of the stuff:
$posts = App\Post::with('timestamp')->get(); // we make Eager Loading
$posts = $posts->sortByDesc('timestamp.publish');
return view('blog.index', compact('posts'));