Laravel检查是否存在记录

I am new to Laravel. Please excuse the newbie question but how do I find if a record exists?

$user = User::where('email', '=', Input::get('email'));

What can I do here to see if $user has a record?

It depends if you want to work with the user afterwards or only check if one exists.

If you want to use the user object if it exists:

$user = User::where('email', '=', Input::get('email'))->first();
if ($user === null) {
   // user doesn't exist
}

And if you only want to check

if (User::where('email', '=', Input::get('email'))->count() > 0) {
   // user found
}

Or even nicer

if (User::where('email', '=', Input::get('email'))->exists()) {
   // user found
}

One of the best solution is to use the firstOrNew or firstOrCreate method. The documentation has more details on both.

It's simple to get to know if there are any records or not

$user = User::where('email', '=', Input::get('email'))->get();
if(count($user) > 0)
{
echo "There is data";
}
else
echo "No data";

this is simple code to check email is exist or not in database

    $data = $request->all();
    $user = DB::table('User')->pluck('email')->toArray();
    if(in_array($user,$data['email']))
    {
    echo 'existed email';
    }

In your Controller

$this->validate($request, [
        'email' => 'required|unique:user|email',
    ]);

In your View - Display Already Exist Message

@if (count($errors) > 0)
    <div class="alert alert-danger">
        <ul>
            @foreach ($errors->all() as $error)
                <li>{{ $error }}</li>
            @endforeach
        </ul>
    </div>
@endif

$user = User::where('email', request('email')->first();
return (count($user) > 0 ? 'Email Exist' : 'Email Not Exist');

if($user->isEmpty()){
    // has no records
}

Eloquent uses collections. See the following link: https://laravel.com/docs/5.4/eloquent-collections

you can use laravel validation .

But this code is also good:

$user = User::where('email',  $request->input('email'))->count();

if($user > 0)
{
   echo "There is data";
}
else
   echo "No data";

if (User::where('email', Input::get('email'))->exists()) {
    // exists
}

This will check if particular email address exist in the table:

if (isset(User::where('email', Input::get('email'))->value('email')))
{
    // Input::get('email') exist in the table 
}

Checking for null within if statement prevents Laravel from returning 404 immediately after the query is over.

if ( User::find( $userId ) === null ) {

    return "user does not exist";
}
else {
    $user = User::find( $userId );

    return $user;
}

It seems like it runs double query if the user is found, but I can't seem to find any other reliable solution.

Laravel 5.6.26v

to find the existing record through primary key ( email or id )

    $user = DB::table('users')->where('email',$email)->first();

then

      if(!$user){
             //user is not found 
      }
      if($user){
             // user found 
      }

include " use DB " and table name user become plural using the above query like user to users

Shortest working options:

// if you need to do something with the user 
if ($user = User::whereEmail(Input::get('email'))->first()) {

    // ...

}

// otherwise
$userExists = User::whereEmail(Input::get('email'))->exists();

$user = User::where('email', '=', Input::get('email'))->first();
if ($user === null) {
   // user doesn't exist
}

can be written as

if (User::where('email', '=', Input::get('email'))->first() === null) {
   // user doesn't exist
}

This will return true or false without assigning a temporary variable if that is all you are using $user for in the original statement.

if ($u = User::where('email', '=', $value)->first())
{
   // do something with $u
   return 'exists';
} else {
  return 'nope';
}

would work with try/catch

->get() would still return an empty array

I think below way is the simplest way to achieving same :

    $user = User::where('email', '=', $request->input('email'))->first();
    if ($user) {
       // user doesn't exist!
    }

Created below method (for myself) to check if the given record id exists on Db table or not.

private function isModelRecordExist($model, $recordId)
{
    if (!$recordId) return false;

    $count = $model->where(['id' => $recordId])->count();

    return $count ? true : false;
}

// To Test
$recordId = 5;
$status = $this->isModelRecordExist( (new MyTestModel()), $recordId);

Home It helps!

if (User::where('email', 'user@email.com')->first())
    // It exists
else
    // It does not exist

Use first(), not count() if you only need to check for existence.

first() is faster because it checks for a single match whereas count() counts all matches.

This will check if requested email exist in the user table:

if (User::where('email', $request->email)->exists()) {
   //email exists in user table
}

$email = User::find($request->email);
If($email->count()>0)
<h1>Email exist, please make new email address</h1>
endif

In laravel eloquent, has default exists() method, refer followed example.

if(User::where('id', $user_id )->exists()){ // your code... }