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!
Related
I'm learning Laravel, so I'm quite new.
I have 2 Models: House and Translation.
My House Model:
use HasFactory;
protected $guarded = ['id'];
public function trans(){
return $this->hasMany(Translation::class);
}
}
My Translation Model:
function House(){
return $this->belongsTo(House::class);
}
}
When I do in the controller something like ($id=2 e.g) :
$house = House::find($id)::with('trans')->get();
I get a result with all houses (there are currently 2 in the DB).
When I just do the query "House::find($id)->get()" it works fine.
What part am I missing?
::with('trans') returns completely new query and forgets everything about your ::find($id)
you need to use load method.
$house = House::find($id);
$house->load('trans');
What happens is, House::find($id) is a method that returns the element by its primary key.
Then, the ::with('trans') gets the result, sees the House class and starts creating a new query builder for the Model.
Finally, the ->get() runs this new query and the end result is what is return for the $house value.
You have two options that will result to what you want to do.
First one is, to find the house entry and then load its relation
$house = House::find($id);
$house->load('trans');
The second option is this:
$house = House::where('id',$id)->with('trans')->first();
The second one is a query builder that results to the first element with id = $id,
and load its relation with translations.
You can check for more details in the laravel documentation. They have a very well-written documentation and the examples help a lot.
I am trying to query data from my database and pass the results to a view called events, the problem I have is that one of my queries will always return the same result because in the where condition the $events_id is the same always. Is there a better way to do the querying? A better logic?
This code is from my controller called EventController:
public function index()
{
$firm_id = DB::table('firms')->where('user_id', auth()->id())->value('id');
$events_id = DB::table('events')->where('firm_id', $firm_id)->value('id');
$events = DB::table('events')->where('firm_id', $firm_id)->get()->toArray();
$actual_events = DB::table('actual_events')->where('event_id', $events_id)->get()->toArray();
return view('events',['events' => $events,'actual_events' => $actual_events]);
}
Since the $events_id is the same every time, the $actual_events will only contain the first result.
The image I have uploaded shows the problem, my table's first three columns are fine. Starting from the fourth they contain repeated values:
As I guess, you need something like this:
$event_ids = DB::table('events')->where('firm_id', $firm_id)->pluck('id');
$actual_events = DB::table('actual_events')->whereIn('event_id', $event_ids)->get()->toArray();
or write about your problem in details and I will try to help you.
you just said that your tables have relation together.
in this case it's better you using the eloquent for that,
first you should type the relations in model of each table like this:
class User extends Authenticatable{
public function cities()
{
return $this->hasmany('App\City'); //you should type your relation
}
}
for relations you can use this link: laravel relationships
after that when you compact the $user variable to your view, you can use this syntax for getting the city value relation to this user: $user->cities;.
I have a Accessor method in Collection Model getSizesAttribute, which returns array of available sizes eg: ['S','L'], Now I need to get Models with have size 'S'. like:
$collections = $collections->where('sizes','S');
But sizes is array, could I manipulate this anyhow so that I could check returns only if sizes have specific size.
I tried making another method getIsSizeAttribute, like:
public function getIsSizeAttribute($size){
return in_array($size,$this->sizes);
}
Now How could I user this in Where condition like
$collections = $collections->where('is_size','S');
Mutators and Accessors only run skin-deep, after the query's already been executed. You could use Collection::filter() as Bangnokia suggests, but that wouldn't give you any performance benefit of actually applying the condition to the initial request.
I think what you're looking for here is a Query Scope. Add something like this to your Model class:
public function scopeSize(\Illuminate\Database\Eloquent\Builder $query, $size)
{
return $query->whereIn('sizes', $this->sizes[$size]);
}
And access it like this:
$collection = $model->size('S')->get();
You should use filter on collection
$collections = $collections->filter(function($item, $index) {
return in_array('S', $item->sizes);
});
I have a table users and posts with columns user_id and post_views.
In post_views I keep information how many times post was display.
And now, in query I would like to get user with sum of post_views all his posts.
I tried do something like this:
User::where(['id'=>$id])->with('posts')->get();
And in model I defined:
public function posts()
{
return $this->hasMany('App\Models\Post')->sum('post_views','AS','totalViews');
}
But without success.
How to do it?
Thank you
You can use a modified withCount():
public function posts()
{
return $this->hasMany('App\Models\Post');
}
$user = User::withCount(['posts as post_views' => function($query) {
$query->select(DB::raw('sum(post_views)'));
}])->find($id);
// $user->post_views
You can use
User::withCount('posts')->find($id)
to get the user with the id $id and a posts_count attribute in the response
I'm not fully sure what the intention of ->sum('game_plays','AS','totalVies'); is - you would need to add more context if you want this
Just something to add with regards to your shown code: No need to query by id using where + the get() at the end will make you query for a collection. If you want to get a single result use find when searching by id
As always laravel has a method for that : withSum (Since Laravel v8)
Note : I know that at the time of the message was posted, the method did not exist, but since I came across this page when I was looking for the same result, I though it might be interesting to share.
https://laravel.com/docs/9.x/eloquent-relationships#other-aggregate-functions
In your case it should be :
$user = User::withSum('posts as total_views', 'post_views')->find($id);
Then you can access to the result :
$user->total_views
Why is this not working?
Article::with('category')->find($ids)
I got a Array to String Conversion Exception.
But if i split the query into 2 parts like this:
$articles = Article::with('category')
and
$articles = $articles->find($ids)
I didn't get any exception and the result is right.
Just for the posterity... other way you can do this is:
Article::with('category')->whereIn('id', $ids)->get();
This should be faster because it's leaving the query to the database manager
Try:
Article::with('category')->get()->find($ids);
You need to get the articles first before you can call find() I believe.
Warning: This retrieves every single article from the database and loads them all into memory, and then selects just one from all that data and returns it. That is probably not how you would want to handle this problem.
This will give you the results based on an array of IDs in Laravel 4
Article::whereIn('id', $ids)->with('category')->get();
Create object and set his properties with relationships
for example, code in your Controller or Service
$article = new Article;
$article = $article->find($id);
$result->article = $article;
$result->article->category = $article->category;
return response()->json($result);
Code in your Model
public function category() {
return $this->hasOne('App\Category');
}