validate max requires for stock_quantity for right quantity sale in sale form not working

I am working on a sales laravelcollective form whereby the sale_quantity entered should not be more than the stock_quantity in DB. When I use the idea at: Laravel validate dynamically added input with custom messages there is one answer with:

'orderQty.*' => 'required|numeric|min:1|max:'.$product['productQty']

I have done this as you will see in my function store and function update in the SalesController.php, no error occurs but the form refuses to submit and shows this as a flash message:

The sale quantity may not be greater than '.$stocks['stock_quantity'].

It does not mean what it shows because their is a greater stock_quantity in the database.

SalesController.php

<?php

namespace App\Http\Controllers;

use Illuminate\Support\Facades\DB;
use Illuminate\Http\RedirectResponse;
use Illuminate\Http\Request;
use App\Sale;
use App\Stock;

class SalesController extends Controller
{
    /**
     * Display a listing of the resource.
     *
     * @return \Illuminate\Http\Response
     */
    function __construct()
    {
        $this->middleware('permission:sales-list');
        $this->middleware('permission:sales-create', ['only' => ['create', 'store']]);
        $this->middleware('permission:sales-edit', ['only' => ['edit', 'update']]);
        $this->middleware('permission:sales-delete', ['only' => ['destroy']]);
}

/**
 * Display a listing of the resource.
 *
 * @return \Illuminate\Http\Response
 */
public function index()
{
    $sales = Sale::orderBy('updated_at', 'desc')->get();
    return view('sales.index')->with('sales', $sales);
}

/**
 * Show the form for creating a new resource.
 *
 * @return \Illuminate\Http\Response
 */
public function create()
{
    $stocks = Stock::all();
    //dd($stocks);
    return view('sales.create', compact('stocks'));
    //$sales = Sale::pluck('stock_id')->prepend('stock_id');
    //$sales = DB::table('stocks')->select('stock_id')->get();
    //return view('sales.create')->with('sales',$sales);
}

public function getUnitSellingPrice(Request $request, $stock_name)
{

    $stock = Stock::where('stock_name', $stock_name)->first();
    if ($stock == null) {
        return null;
    }

    return response()->json($stock->unit_selling_price);
}

public function store(Request $request)
{
    $this->validate($request, [
        'stock_name' => 'required',
        'sale_quantity' => 'required|numeric|min:1|max:\'.$stock[\'stock_quantity\']',
        'unit_selling_price' => 'required',
        'total_sales_cost' => 'required'
    ]);

    //create stock
    $sale = new Sale;
    $sale->stock_name = $request->input('stock_name');
    $sale->sale_quantity = $request->input('sale_quantity');
    $sale->unit_selling_price = $request->input('unit_selling_price');
    $sale->total_sales_cost = $request->input('total_sales_cost');
    $sale->save();
    DB::table('stocks')->where('stock_name', $request->input('stock_name'))->decrement('stock_quantity', $request->input('sale_quantity'));

    return redirect('/sales')->with('success', 'Sale Saved');
}


public function show($sales_id)
{
    $sale = Sale::find($sales_id);
    return view('sales.show')->with('sale', $sale);
}

/**
 * Show the form for editing the specified resource.
 *
 * @param  int $sales_id
 * @return \Illuminate\Http\Response
 */
public function edit($sales_id)
{
    $sale = Sale::findOrFail($sales_id);
    $stocks = Stock::latest('stock_name', 'unit_selling_price')->get();
    return view('sales.edit', compact('sale', 'stocks'));
}

/**
 * Update the specified resource in storage.
 *
 * @param  \Illuminate\Http\Request $request
 * @param  int $sales_id
 * @return \Illuminate\Http\Response
 */
public function update(Request $request, $sales_id)
{
    $this->validate($request, [
        'stock_name' => 'required',
        'sale_quantity' => 'required|numeric|min:1|max:\'.$stock[\'stock_quantity\']',
        'unit_selling_price' => 'required',
        'total_sales_cost' => 'required'

    ]);

    //create stock
    $sale = Sale::find($sales_id);
    $sale->stock_name = $request->input('stock_name');
    $sale->sale_quantity = $request->input('sale_quantity');
    $sale->unit_selling_price = $request->input('unit_selling_price');
    $sale->total_sales_cost = $request->input('total_sales_cost');
    $sale->save();

    return redirect('/sales')->with('success', 'Sale Updated');
}

/**
 * Remove the specified resource from storage.
 *
 * @param  int $sales_id
 * @return \Illuminate\Http\Response
 */
public function destroy($sales_id)
{
    $sale = Sale::find($sales_id);
    $sale->delete();
    return redirect('/sales')->with('success', 'Sale Removed');
}
}

create.blade.php

@extends('layouts.app')

@section('content')
    <br>
    <h1>Add Sale</h1>
    {!! Form::open(['action' => 'SalesController@store', 'method' => 'POST', 'enctype' => 'multipart/form-data']) !!}

<div class="form-group">
    <label>Product Name</label>
    <select name="stock_name" id="stock_name" class="form-control">
        @foreach ($stocks as $stock)
            <option value=""></option>
        @endforeach
    </select>
</div>

<div class="form-group">
    
    
</div>

<div class="form-group">
    
    
</div>

<div class="form-group">
    
    
</div>


{!! Form::close() !!}

<script>
    $(document).ready(function () {
        $("#stock_name").on('change', function () {
            var stock_name = $(this).val();
            $.ajax({
                url: '/sales-price/getunitsellingprice/'+stock_name,
                method: 'GET',
                success: function (response) {
                    console.log(response);
                    $("#unit_selling_price").val(response);
                },
            });
        });
    });
</script>


<script>
    $(document).ready(function () {
        $("#total_sales_cost").click(function () {
            var sales_quantity = $("#sales_quantity").val();

            var unit_selling_price = $("#unit_selling_price").val();
            var total_sales_cost = (sales_quantity * unit_selling_price);

            $('#total_sales_cost').val(total_sales_cost);
        });
    });
</script>
@endsection

via Chebli Mohamed