CODEWITHSUNDEEP
scalaplayframework-2.0
ScalaBoy
ScalaBoy

Reputation: 85

Errors in Forms miss match type

 details.bindFromRequest.fold(
    errors => BadRequest(views.html.adminpages.aboutusimgsForm(errors)),

[NoSuchElementException: None.get]

From this form

@(details: Form[AboutImages])

<input type="hidden" name="id" value="@details.get.id">
<input type="text" name="name" value="@details.get.name">

I have an edit form aboutusimgs/edit/1 that adds text and hidden form inputs from the databases(mysql).

But when I don't fill in the form and the error part of the bind executes:

errors => BadRequest(views.html.adminpages.aboutusimgsForm(errors)),

I get the NoSuchElementException do I have make another form just for errors why can I just use the edit form?

Thanks

Upvotes: 3

Views: 570

Answers (3)

korefn
korefn

Reputation: 955

Assuming you have a List[Option[String]] or Seq ... the solution would be to use flatMap which removes None so 

List(Some("Message"),None).map{ _.get.split(" ") } //throws error

but if you use flatmap

List(Some("Message"),None).flatMap{ i => i }.map{ _.split(" ") } //Executes without errors

Upvotes: 0

Mik378
Mik378

Reputation: 22191

To work with Option's results, you should never ever use get method directly.

Why? Because it leads exactly to a potential NullPointerException concept from Java (since throwing NoSuchElementException by None) => preventing safety in your way of coding.

To retrieve result and especially do something according to the retrieved value, prefer pattern matching or better, the shorter fold method: 

/** Returns the result of applying $f to this $option's
   *  value if the $option is nonempty.  Otherwise, evaluates
   *  expression `ifEmpty`.
   *
   *  @note This is equivalent to `$option map f getOrElse ifEmpty`.
   *
   *  @param  ifEmpty the expression to evaluate if empty.
   *  @param  f       the function to apply if nonempty.
   */
  @inline final def fold[B](ifEmpty: => B)(f: A => B): B =
    if (isEmpty) ifEmpty else f(this.get)

Alternatively, you can choose to use getOrElse method if you only want to retrieve the Option's result and provide a default value if you deal with a None: 

  /** Returns the option's value if the option is nonempty, otherwise
   * return the result of evaluating `default`.
   *
   *  @param default  the default expression.
   */
  @inline final def getOrElse[B >: A](default: => B): B =
    if (isEmpty) default else this.get

Upvotes: 0

drexin
drexin

Reputation: 24403

The problem here is, that if a value is not set, it will have None as value. None.get always throws a NoSuchElementException, because it obviously has no element. You can handle Options in several ways, but if you have a default, you can simply use getOrElse. E.g:

// first map it to the id, then get the value or default if None
details.map(_.id).getOrElse("")

You should also have a look at the the scala docs for the Option type and read one or two of the several articles about how to use options.

Upvotes: 1

Related Questions