Calculate hours for training - laravel

Question

I have some hesitations about 3 tables which are type_training , training & payment.
In the table type_training, I have a field named price with 4 amounts: for example:
1 hour 00 = 100 euros
1 hour 30 = 150 euros
2 hour 00 = 200 euros
2 hour 30 = 250 euros
In my page Training , I encode 2 recordings for the same student.
The student Dujardin has booked 3 hours for 300 euros.
In my form Payment, is it possible to retrieve the amount of 300 ?
So, in my Model Payment? I must to calculate the difference between the hour start and the hour end?
I don't know how to do ?
Then, after having retrieved the difference of hours in my example we have 3 hours.
How to I sum my 2 recordings in my field Total ? I have tried this?
$typetraining = Typetraining::find($request->fk_typetraining);
$data = $request->all();
$data['total'] = $typetraining->price + $request->????;
Payment::create($data);
In summary:
1) How to retrieve the difference between hour start & hour end,
2) How to calculate the amounts via the duration of my training?
For information, here is my architecture.
I thank you for your help and your explanations.
Edit: Watercamyan 19/09/2019
I adapat this?
createFromFormat('H:i', $request->get('hour_start'))
Per:
<div class="form-group{{ $errors->has('hour_start') ? 'has-error' : '' }}">
<label for="form-group-input-1">Hour start</label>
<input type="text" name="hour_start" id="hour_start" class="form-control" required="required" value="{{ old('hour_start')}}"/>
{!! $errors->first('hour_start', '<span class="help-block">:message</span>') !!}
</div>
Then, in my model Training I have like error message: Undefined variable: typeseances
$start = Carbon::parse($request->get('hour_start'));
$end= Carbon::parse($request->get('hour_end'));
$mins = $end->diffInMinutes($start, true);
$hoursTraining = $mins/60;
$total = $**typeTraining**->price * $hoursTraining;
I have like error message: Undefined variable: typeseances

Answer 1

I think, as JoeGalind said, you should seriously consider re-archetecting this to be simpler. Having to call a TypeTraining object that has nothing but a price, should indeed be moved up to the Training object. However, let me go through a way to solve it with your existing code.
First, as you said, you need to get the number of hours of the requested training. Unfortunately, you need part hours instead of whole hours to change the price. If you needed whole hours, this would be easy, you could use the Carbon method diffInHours(). But we can do it with diffInMinutes(), and then calculate out the partial hour.
First, we need to parse the hours coming in from the form into a Carbon object:
$start = Carbon::parse($request->get('hour_start'));
$end= Carbon::parse($request->get('hour_end'));
Note, I don't know how it is coming in from your form. You might need to parse it differently if the above doesn't work. Something like:
createFromFormat('H:i', $request->get('hour_start'))
or
createFromFormat('H:i:s', $request->get('hour_start'))
Now that you've got a carbon object, we need to calculate out the difference, including the part hours. Again, we'll use the minutes and calculate for part hours:
$mins = $end->diffInMinutes($start, true);
$hoursTraining = $mins/60;
This will yield your multiplier (the number of hours training), something like 2.0 or 2.5 or 2.25, etc. From here, if you have a base price for one hour (which is what I expect is in that TypeTraining model's price field), it is easy:
$total = $typeTraining->price * $hoursTraining;
The hard part, based on the way you have your code set up, is that you must pull the TypeTraining along with the Training, in order to know the price (again - just stick the price on the training to make life easier).
To get the price, something like this:
$training = Training::with('typeTraining')->where('fk_student', $request->get('fk_student)->first();
$price = $training->typeTraining->price;
Now you have the price to plug into the formula above.
This is surely not exact. And pulling the training with the FK on student is probably not what you want. If it is generic training, or there is some other identifier, use that to pull the training to get the price. But you can decide that later. I can only guess at some of this, as I don't know what's coming in, or what your query needs to be, or your relationships, but this should give you an idea. Most importantly, you were asking for how to calculate total, which is answered farther above.

Answer 2

I would recommend the following:
Add a "price" field to the training table. This way, if in the future, you increment that price, all your history stays with the current price.
After saving your "training", go ahead and calculate the hours between both dates using Carbon library, and select your current price from the TypeTraining table using this value.
Store the value on the Training table and then you can easily calculate the sum from anywhere.