I cannot save data from angular to backend laravel database

I am passing form input from angular to laravel view api. But data cannot be saved in the database. I am getting the following error messages in the console:

error: [ngRepeat:dupes] http://ift.tt/1RTr3Vm
    at Error (native)
    at http://localhost/myapp/public/app/lib/angular-1.5.0/angular.min.js:6:416
    at http://localhost/myapp/public/app/lib/angular-1.5.0/angular.min.js:292:254
    at http://localhost/myapp/public/app/lib/angular-1.5.0/angular.min.js:137:302
    at m.$digest (http://localhost/myapp/public/app/lib/angular-1.5.0/angular.min.js:138:399)
    at m.$apply (http://localhost/myapp/public/app/lib/angular-1.5.0/angular.min.js:141:341)
    at g (http://localhost/myapp/public/app/lib/angular-1.5.0/angular.min.js:94:139)
    at t (http://localhost/myapp/public/app/lib/angular-1.5.0/angular.min.js:98:260)
    at XMLHttpRequest.u.onload (http://localhost/myapp/public/app/lib/angular-1.5.0/angular.min.js:99:297)(anonymous function) @ angular.js:13236
apps.js:28 0
http://localhost/myapp/public/api/apps Failed to load resource: the server responded with a status of 500 (Internal Server Error)
I also get laravel errors:
                            <span class="exception_title"><abbr title="Illuminate\Database\QueryException">QueryException</abbr> in <a title="C:\xampp\htdocs\dukamart\vendor\laravel\framework\src\Illuminate\Database\Connection.php line 651" ondblclick="var f=this.innerHTML;this.innerHTML=this.title;this.title=f;">Connection.php line 651</a>:</span>
span class="exception_message">SQLSTATE[23000]: Integrity constraint violation: 1048 Column associated with input values. 

I have checked my laravel controller seem to be fine. I am posting data from a popup form.

employeeController.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

use App\Http\Requests;
use App\Http\Controllers\Controller;
use App\Employee;

class Employees extends Controller
{
    //
     public function index($id = null) {
        if ($id == null) {
            return Employee::orderBy('id', 'asc')->get();
        } else {
            return $this->show($id);
        }
    }

    public function store(Request $request) {
        $employee = new Employee;

        $employee->name = $request->input('name');
        $employee->email = $request->input('email');
        $employee->contact_number = $request->input('contact_number');
        $employee->position = $request->input('position');
        $employee->save();

        return 'Employee record successfully created with id ' . $employee->id;
    }

//My angular controller

app.controller('employeesController', function($scope, $http, API_URL) {
    //retrieve employees listing from API
    $http.get(API_URL + "employees")
            .success(function(response) {
                $scope.employees = response;
            });

    //show modal form
    $scope.toggle = function(modalstate, id) {
        $scope.modalstate = modalstate;

        switch (modalstate) {
            case 'add':
                $scope.form_title = "Add New Employee";
                break;
            case 'edit':
                $scope.form_title = "Employee Detail";
                $scope.id = id;
                $http.get(API_URL + 'employees/' + id)
                        .success(function(response) {
                            console.log(response);
                            $scope.employee = response;
                        });
                break;
            default:
                break;
        }
        console.log(id);
        $('#myModal').modal('show');
    }

    //save new record / update existing record
    $scope.save = function(modalstate, id) {
        var url = API_URL + "employees";

        //append Employee id to the URL if the form is in edit mode
        if (modalstate === 'edit'){
            url += "/" + id;
        }

        $http({
            method: 'POST',
            url: url,
            data: $.param($scope.employee),
        headers: {'Content-Type': 'application/x-www-form-urlencoded'}
        }).success(function(response) {
            console.log(response);
            location.reload();
        }).error(function(response) {
            console.log(response);
            alert('This is embarassing. An error has occured. Please check the log for details');
        });
    }

    //delete record
    $scope.confirmDelete = function(id) {
        var isConfirmDelete = confirm('Are you sure you want this record?');
        if (isConfirmDelete) {
            $http({
                method: 'DELETE',
                url: API_URL + 'employees/' + id
            }).
                    success(function(data) {
                        console.log(data);
                        location.reload();
                    }).
                    error(function(data) {
                        console.log(data);
                        alert('Unable to delete');
                    });
        } else {
            return false;
        }
    }
});

When I click to save the data, I am getting an error message I had setup in employeeController.js controller

$http({
            method: 'POST',
            url: url,
            data: $.param($scope.hotel),
        headers: {'Content-Type': 'application/x-www-form-urlencoded'}
        }).success(function(response) {
            console.log(response);
            location.reload();
        }).error(function(response) {
            console.log(response);
            alert('This is embarassing. An error has occured. Please check the log for details');
        });
    }

This my app.js

var app = angular.module(employees, [])
        .constant('API_URL', 'http://localhost/myapp/public/api/');

My routes.php

Route::get('/api/v1/employees/{id?}', 'Employees@index');
Route::post('/api/v1/employees', 'Employees@store');
Route::post('/api/v1/employees/{id}', 'Employees@update');
Route::post('/api/v1/employees/update/{id}',['as'=>'update','uses'=> 'Employees@update']);
Route::delete('/api/v1/employees/{id}', 'Employees@destroy');

What could be the cause of this? Please help. I have tried to solve this for 3 days without success.

via Chebli Mohamed