Hi I am new to Laravel and php. In my database each student has three marks on each subject and I need to retrieve them and send to the view the average mark for each student.
I tried doing it like below, but the returned value is an object (e.g. [5,4,3]) and it doesn't let me count the average. Please advise how I can operate with data within the object.
$students = Student::all();
foreach ($students as $student) {
$mathPoints = Point:: where('subject_id', 1)
->where('student_id', $student->id)
->pluck('points');
}
I tried turning it into an array by (array) method, but I couldn't calculate the sum of values with array_sum after.
Update: my Point model:
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Point extends Model
{
//Get the student the credit points are related to
public function student()
{
return $this->belongsTo('App/Models/Student');
}
//Get the subject the credit points are related to
public function subject()
{
return $this->belongsTo('App/Models/Subject');
}
}
use Model::avg('columnName') to calculate average .
read more here : https://laravel.com/docs/5.4/queries#aggregates
$students = Student::all();
foreach ($students as $student){
$mathPoints = Point::where(['subject_id'=>1,'student_id'=>$student->id])->avg('points');
$student->avgPoint=$mathPoints;
}
inside your blade :
{{ $student->avgPoint}}
Point::where('student_id', $student->id)->get()
When you use all() with Eloquent, it makes the query for you. If you use where(), you have to ‘get’ it using get() before you can use it as a collection.
$mathPoints = Point::where('student_id', $student->id)
->get()
->pluck('points');
However, I’d probably look at using more complicated queries to fetch this data, as you could easily end up making hundreds of queries per page, rather than just 1.
Related
Suppose I have Three model named as Customer ,Invoice and Payment.
Invoice and Payment model looks like
id , customer_id, amount
I want to get only those customer whose
Invoice.sum(amount)>Payment.sum(amount) with these amount difference
I am currently retrieve like
$customers=Customer::get();
foreach($customers as $customer)
{
$pay=Payment::where('customer_id',$customer->id)->sum('amount');
$due=Invoice::where('customer_id',$customer->id)->sum('amount');
if($due>$pay){
// showing this customers
}
}
Is there any better way with eloquent join?
How Can I get In laravel eloquent ?
Have you set any relationship in the Model? A better eloquent query will look like this. You might need to adjust a bit
Customer::join('payment','customer.id','=','payment.customer_id')
->join('invoice','customer.id','=','invoice.customer_id')
->select(array('customer.*'),DB::raw("SUM(payment.amount) as payment_sum,SUM(invoice.amount) as invoice_sum"))
//->where('customer_id',$customer->id)
->groupBy('customer.id') //replace with anything that make sense for you.
->havingRaw('invoice_sum > payment_sum')
->get();
Try this
First, define the relationship in your Customer Model
public function payments()
{
return $this->hasMany(Payment::class); //based on your logic or structure
}
public function invoices()
{
return $this->hasMany(Invoice::class); //based on your logic or structure
}
Customer::with(['payments' => function($query) {
$query->sum('amount');
}])
->get();
or
$customers=Customer::with('payments','invoices')->get();
foreach($customers as $customer)
{
$pay = $customer->payments()->sum('amount');
$due = $customer->invoices()->sum('amount');
//other logic
}
I'm trying to loop through the items using eloquent in laravel but I'm getting 0. Please see my code below.
Model
Class Store{
public function products(){
return $this->hasMany('App\Product');
}
}
Controller
$products_count = 0;
foreach($store->products() as $product)
{
if($product->status == 1)
{
$products_count++;
}
}
dd($products_count);
Note: I have data in my database.
You can also use withCount method something like that
Controller
$stores = Store::withCount('products')->get();
or
$store = Store::where('id', 1)->withCount('products')->first();
WithCount on the particular status
$stores = Store::withCount(['products' => function ($query) {
$query->where('status', 1);
}
])
->get();
ref: withcount on relationship
That's because $store->products() returns an eloquent collection which doesn't contain the data from the database yet. You need to do $store->products instead.
If you need to get the count from the database then use
$store->products()->where('status', 1)->count()
With the function-annotation (i.e. products()) you are retrieving the \Illuminate\Database\Eloquent\Builder-instance, not the actual Eloquent-collection.
Instead, you would have to use $store->products – then you will get retrieve the related collection.
In Laravel $store->products() makes you access the QueryBuilder instance, instead there is the Laravel way of doing $store->products, which loads the QueryBuilder and retrieves the collection automatically and down the line is easy to optimise.
I have the following relationship:
A venue has many offers
A offer has many orders
I have the following Eloquent model to represent this:
class Venue {
public function orders()
{
return $this->hasManyThrough(Order::class, Offer::class);
}
}
I want to determine the total number of orders for venues with location_id = 5 using Laravel's Eloquent model.
The only way I managed to do this is as follows:
$venues = Venue::where('location_id', 5)->with('orders')->get();
$numberOfOrders = 0;
foreach($venues as $venue) {
$numberOfOrders += $venue->orders->count();
}
dump($numberOfOrders); // Output a single number (e.g. 512)
However, this is obviously not very efficient as I am calculating the count using PHP instead of SQL.
How can I do this using Eloquent model alone.
You can use Eloquent. As of Laravel 5.3 there is withCount().
In your case you will have
$venues = Venue::where('location_id', 5)->with('orders')->withCount('orders')->get();
Then access it this way
foreach ($venues as $venue) {
echo $venue->orders_count;
}
Can find reference here: https://laravel.com/docs/5.3/eloquent-relationships#querying-relations
$venues = Venue::with([
'orders' => function ($q) {
$q->withCount('orders');
}
])->get();
then use it this way for getting single record
$venues->first()->orders->orders_count();
Alternatively, you can use this way too for collections
foreach($venues as $venue)
{
echo $venue->order_count;
}
If you are using Laravel 5.3 or above you can use withCount.
If you want to count the number of results from a relationship without
actually loading them you may use the withCount method, which will
place a {relation}_count column on your resulting models. For example:
$venues = Venue::withCount(['orders'])->get;
foreach ($venues as $venue) {
echo $venue->orders_count;
}
You can read more about withCount in the Laravel Documentation.
If you are using lower than 5.3, you can make a custom relation on your Venue model:
public function ordersCount()
{
return $this->belongsToMany('App\Models\Order')
->selectRaw('venue_id, count(*) as aggregate_orders')
->groupBy('venue_id');
}
public function getOrderCount()
{
// if relation is not loaded already, let's do it first
if (!array_key_exists('ordersCount', $this->relations)) {
$this->load('ordersCount');
}
$related = $this->getRelation('ordersCount')->first();
// then return the count directly
return ($related) ? (int) $related->aggregate_orders : 0;
}
which can then be used as: Venue::with('ordersCount');. The benefit of this custom relation is you only are querying the count rather than the querying all of those relations when they are not necessary.
I have a situtaion where I have data in two columns in a table, which need to be multiplied on a row basis. Then each value from the multiplication has to be added to provide a net result
I tried this but it does not work
public function getCampaignStats($item)
{
$query = CampaignStats::where('item',$item);
foreach($query as $q) {
$q->p_c;
$q->caa;
dd($q->p_c);
}
return $query;
}
I get this exception when i try to do this
Object of class Illuminate\Database\Eloquent\Builder could not be converted to string
Is there a better way to do this foreach loop in laravel
You can use raw queries for such a case and do the math within your query. Have a look at the docs:
https://laravel.com/docs/5.4/queries#raw-expressions
https://laravel.com/docs/5.4/queries#where-exists-clauses
I have a Poll table, a Students table, and a pivot table between them that includes a token and their three votes.
public function students()
{
return $this->belongsToMany('Student', 'polls_students')->withPivot('token','first','second','third');
}
While working out saving the poll results, I came across some odd behavior that I don't quite understand. I'm hoping somebody can explain what it is I'm missing:
$poll = Poll::find(Input::get('poll_id'));
foreach($poll->students()->where('students.id', '=', Input::get('student_id'))->get() as $student){
var_dump($student->pivot->token);
}
$student = $poll->students()->where('students.id', '=', Input::get('student_id'))->get();
var_dump($student->pivot->token);
In the above code, the foreach loop will successfully display the token, where the second one throws the exception Undefined property: Illuminate\Database\Eloquent\Collection::$pivot
What am I missing? Are these two calls not logically creating the same object? How is 'pivot' working on the first and not the latter?
You first example:
$poll = Poll::find(Input::get('poll_id'));
foreach($poll->students()->where('students.id', '=', Input::get('student_id'))->get() as $student){
var_dump($student->pivot->token);
}
Here $poll->students() retrieves a collection and because of foreach loop you get a single object in your $student variable and you can use $student->pivot->token
You second example:
$student = $poll->students()->where('students.id', '=', Input::get('student_id'))->get();
var_dump($student->pivot->token);
Here you are doing same thing, using $poll->students() you are getting a collection but this time you are not using a loop and trying to do same thing using $student->pivot->token but it's not working because you didn't define any index from which you want to get the pivot->token, if you try something like this
$student->first()->pivot->token
Or maybe
$student->get(1)->pivot->token
Or maybe you can use first() instead of get() like this
$student = $poll->students()->where('students.id', '=', Input::get('student_id'))->first();
Then you can use
$student->pivot->token
Remember that, get() returns a collection even if there is only one record/model.
$poll = Poll::find(Input::get('poll_id'));
foreach($poll->students as $student){
var_dump($student->pivot->where('student_id',$student->id)->where('poll_id',$poll->id)->first()->token);
}