Laravel check for constraint violation

first put this in your controller

use Exception;

second handle the error by using try catch like this example

try{    //here trying to update email and phone in db which are unique values
        DB::table('users')
            ->where('role_id',1)
            ->update($edit);
        return redirect("admin/update_profile")
               ->with('update','update');
            }catch(Exception $e){
             //if email or phone exist before in db redirect with error messages
                return redirect()->back()->with('phone_email','phone_email_exist before');
            }

New updates here without need to use try catch you can easily do that in validation rules as the following code blew

public function update(Request $request, $id)
{
    $profile = request()->all();
    $rules    = [
            'name'                       => 'required|unique:users,id,'.$id,
            'email'                      => 'required|email|unique:users,id,'.$id,
            'phone'                      => 'required|unique:users,id,'.$id,
    ];
    $validator = Validator::make($profile,$rules);
    if ($validator->fails()){
        return redirect()->back()->withInput($profile)->withErrors($validator);
    }else{
        if(!empty($profile['password'])){
            $save['password'] = bcrypt($profile['password']);
        }
        $save['name']                  = $profile['name'];
        $save['email']                 = $profile['email'];
        $save['phone']                 = $profile['phone'];
        $save['remember_token']        = $profile['_token'];
        $save['updated_at']            = Carbon::now();

        DB::table('users')->where('id',$id)->update($save);
        return redirect()->back()->with('update','update');
    }
}

where id related to record which you edit.

You are looking for the 23000 Error code (Integrity Constraint Violation). If you take a look at QueryException class, it extends from PDOException, so you can access to $errorInfo variable.

To catch this error, you may try:

try {
  // ...

} catch (\Illuminate\Database\QueryException $e) {
    var_dump($e->errorInfo);
}

// Example output from MySQL
array (size=3)
   0 => string '23000' (length=5)
   1 => int 1452
   2 => string 'Cannot add or update a child row: a foreign key constraint fails (...)'

To be more specific (Duplicate entry, not null, add/update child row, delete parent row...), it depends on each DBMS:

• PostgreSQL and SQL server follow the SQL standard's conventions for SQLSTATE code, so you may return the first value from the array $e->errorInfo[0] or call $e->getCode() directly
• MySQL, MariaDB and SQLite do not strictly obey the rules, so you need to return the second value from the array $e->errorInfo[1]

For laravel, handling errors is easy, just add this code in your "app/start/global.php" file ( or create a service provider):

App::error(function(\Illuminate\Database\QueryException $exception)
{
    $error = $exception->errorInfo;
    // add your business logic
});