implicit class ScalaObservable[T] extends AnyRef
Extends the Java Observable and adds helpers to make Observables composable and simple to Subscribe to.
- T
the type of result the Observable emits
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Instance Constructors
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new
ScalaObservable(observable: Observable[T])
- observable
the original Observable
Value Members
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final
def
!=(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
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final
def
##(): Int
- Definition Classes
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final
def
==(arg0: Any): Boolean
- Definition Classes
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-
def
andThen[U](pf: PartialFunction[Try[T], U]): Observable[T]
Applies the side-effecting function to the final result of this Observable and, returns a new Observable with the result of this Observable.
Applies the side-effecting function to the final result of this Observable and, returns a new Observable with the result of this Observable.
This method allows one to enforce that the callbacks are executed in a specified order.
Note that if one of the chained
andThen
callbacks throws an exception, that exception is not propagated to the subsequentandThen
callbacks. Instead, the subsequentandThen
callbacks are given the original value of this Observable.The following example prints out
10
:Observable(1 to 10) andThen { case r => sys.error("runtime exception") } andThen { case Success(x) => print(x) case Failure(t) => print("Failure") }
- U
the result type of the
- pf
the partial function to pattern match against
- returns
an
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final
def
asInstanceOf[T0]: T0
- Definition Classes
- Any
-
def
clone(): AnyRef
- Attributes
- protected[java.lang]
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- @throws( ... )
-
def
collect[S](): SingleObservable[Seq[T]]
Collects all the values of the Observable into a list and returns a new Observable with that list.
Collects all the values of the Observable into a list and returns a new Observable with that list.
Example:
val listOfNumbers = Observable(1 to 100).collect()
- returns
an Observable that emits a single item, the result of accumulator.
- Note
If the Observable is large then this will consume lots of memory! If the underlying Observable is infinite this Observable will never complete.
- See also
Uses foldLeft underneath
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final
def
eq(arg0: AnyRef): Boolean
- Definition Classes
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def
equals(arg0: Any): Boolean
- Definition Classes
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-
def
fallbackTo[U >: T](that: Observable[U]): Observable[U]
Creates a new Observable which returns the results of this Observable, if there is an error, it will then fallback to returning the results of the alternative "
that
" Observable.Creates a new Observable which returns the results of this Observable, if there is an error, it will then fallback to returning the results of the alternative "
that
" Observable.If both Observables fail, the resulting Observable holds the throwable object of the first Observable.
Example:
val fallBackObservable = Observable(1 to 100) fallbackTo Observable(200 to 300)
Ensuring results from a Single Observer
fallbackTo
can potentially emit results from either Observer. This often isn't desirable, so to ensure only a single Observable issues results combine with the collect method eg:val results = Observable(1 to 100).collect() fallbackTo Observable(200 to 300).collect()
- U
the type of the returned Observable
- that
the Observable to fallback to if
this
Observable fails- returns
an Observable that will fallback to the
that
Observable shouldthis
Observable complete with anonError
.
-
def
filter(predicate: (T) ⇒ Boolean): Observable[T]
Creates a new Observable by filtering the value of the current Observable with a predicate.
Creates a new Observable by filtering the value of the current Observable with a predicate.
If the current Observable fails, then the resulting Observable also fails.
Example:
val oddValues = Observable(1 to 100) filter { _ % 2 == 1 }
- predicate
the function that is applied to each result emitted if it matches that result is passes to the returned Observable
- returns
an Observable only containing items matching that match the predicate
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def
finalize(): Unit
- Attributes
- protected[java.lang]
- Definition Classes
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- Annotations
- @throws( classOf[java.lang.Throwable] )
-
def
flatMap[S](mapFunction: (T) ⇒ Observable[S]): Observable[S]
Creates a new Observable by applying a function to each emitted result of the Observable.
Creates a new Observable by applying a function to each emitted result of the Observable. If the Observable calls errors then then the new Observable will also contain this exception.
As each emitted item passed to
onNext
returns an Observable, we tightly control the requests to the parent Observable. The requested amount is then passed to the child Observable and only when that is completed does the parent become available for requesting more data.Example:
def f = Observable(1 to 10) def g = Observable(100 to 100) val h = for { x: Int <- f // returns Observable(1 to 10) y: Int <- g // returns Observable(100 to 100) } yield x + y
is translated to:
f flatMap { (x: Int) => g map { (y: Int) => x + y } }
- S
the resulting type of each item in the Observable
- mapFunction
function that transforms a each result of the receiver into an Observable and passes each result of that Observable to the returned Observable.
- returns
an Observable with transformed results and / or error.
-
def
foldLeft[S](initialValue: S)(accumulator: (S, T) ⇒ S): SingleObservable[S]
Creates a new Observable that contains the single result of the applied accumulator function.
Creates a new Observable that contains the single result of the applied accumulator function.
The first item emitted by the Observable is passed to the supplied accumulator function alongside the initial value, then all other emitted items are passed along with the previous result of the accumulator function.
Example:
val countingObservable = Observable(1 to 100) foldLeft(0)((v, i) => v + 1)
- initialValue
the initial (seed) accumulator value
- accumulator
an accumulator function to be invoked on each item emitted by the source Observable, the result of which will be used in the next accumulator call.
- returns
an Observable that emits a single item, the result of accumulator.
- Note
If this function is used to collect results into a collection then it could use lots of memory! If the underlying Observable is infinite this Observable will never complete.
-
def
foreach[U](doOnEach: (T) ⇒ U): Unit
Applies a function applied to each emitted result.
Applies a function applied to each emitted result.
Automatically requests all results
- U
the resulting type after the transformation
- doOnEach
the anonymous function applied to each emitted item
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final
def
getClass(): Class[_]
- Definition Classes
- AnyRef → Any
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def
hashCode(): Int
- Definition Classes
- AnyRef → Any
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def
head(): Future[T]
Returns the head of the Observable in a scala.concurrent.Future.
Returns the head of the Observable in a scala.concurrent.Future.
- returns
the head result of the Observable.
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final
def
isInstanceOf[T0]: Boolean
- Definition Classes
- Any
-
def
map[S](mapFunction: (T) ⇒ S): Observable[S]
Creates a new Observable by applying a function to each emitted result of the Observable.
Creates a new Observable by applying a function to each emitted result of the Observable. If the Observable calls errors then then the new Observable will also contain this exception.
Example:
def f = Observable(1 to 10) def g = Observable(100 to 100) val h = for { x: Int <- f // returns Observable(1 to 10) y: Int <- g // returns Observable(100 to 100) } yield x + y
is translated to:
f flatMap { (x: Int) => g map { (y: Int) => x + y } }
- S
the resulting type of each item in the Observable
- mapFunction
function that transforms a each result of the receiver and passes the result to the returned Observable
- returns
an Observable with transformed results and / or error.
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final
def
ne(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef
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final
def
notify(): Unit
- Definition Classes
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final
def
notifyAll(): Unit
- Definition Classes
- AnyRef
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def
observeOn(context: ExecutionContext): Observable[T]
Use a specific execution context for future operations
Use a specific execution context for future operations
- context
the execution context
- returns
an Observable that uses the specified execution context
-
def
recover[U >: T](pf: PartialFunction[Throwable, U]): Observable[U]
Creates a new Observable that will handle any matching throwable that this Observable might contain.
Creates a new Observable that will handle any matching throwable that this Observable might contain. If there is no match, or if this Observable contains a valid result then the new Observable will contain the same.
Example:
mongoExceptionObservable recover { case e: MongoException => 0 } // final result: 0 mongoExceptionObservable recover { case e: NotFoundException => 0 } // result: exception
- U
the type of the returned Observable
- pf
the partial function used to pattern match against the
onError
throwable- returns
an Observable that will handle any matching throwable and not error.
-
def
recoverWith[U >: T](pf: PartialFunction[Throwable, Observable[U]]): Observable[U]
Creates a new Observable that will handle any matching throwable that this Observable might contain by assigning it a value of another Observable.
Creates a new Observable that will handle any matching throwable that this Observable might contain by assigning it a value of another Observable.
If there is no match, or if this Observable contains a valid result then the new Observable will contain the same result.
Example:
successfulObservable recoverWith { case e: ArithmeticException => observableB } // result: successfulObservable mongoExceptionObservable recoverWith { case t: Throwable => observableB } // result: observableB
Ensuring results from a Single Observer
recoverWith
can potentially emit results from either Observer. This often isn't desirable, so to ensure only a single Observable issues results combine with the collect method eg:val results = Observable(1 to 100) .collect() .recoverWith({ case t: Throwable => Observable(200 to 300).collect() }) .subscribe((i: Seq[Int]) => print(results))
- U
the type of the returned Observable
- pf
the partial function used to pattern match against the
onError
throwable- returns
an Observable that will handle any matching throwable and not error but recover with a new observable
-
def
subscribe(doOnNext: (T) ⇒ Any, doOnError: (Throwable) ⇒ Any, doOnComplete: () ⇒ Any): Unit
Subscribes to the Observable and requests
Long.MaxValue
.Subscribes to the Observable and requests
Long.MaxValue
.Uses the default or overridden
onNext
,onError
,onComplete
partial functions.- doOnNext
anonymous function to apply to each emitted element.
- doOnError
anonymous function to apply if there is an error.
- doOnComplete
anonymous function to apply on completion.
-
def
subscribe(doOnError: (Throwable) ⇒ Any, doOnComplete: () ⇒ Any): Unit
Subscribes to the Observable and requests
Long.MaxValue
.Subscribes to the Observable and requests
Long.MaxValue
.- doOnError
anonymous function to apply if there is an error.
- doOnComplete
anonymous function to apply on completion.
-
def
subscribe(doOnNext: (T) ⇒ Any, doOnError: (Throwable) ⇒ Any): Unit
Subscribes to the Observable and requests
Long.MaxValue
.Subscribes to the Observable and requests
Long.MaxValue
.- doOnNext
anonymous function to apply to each emitted element.
- doOnError
anonymous function to apply if there is an error.
-
def
subscribe(doOnNext: (T) ⇒ Any): Unit
Subscribes to the Observable and requests
Long.MaxValue
.Subscribes to the Observable and requests
Long.MaxValue
.- doOnNext
anonymous function to apply to each emitted element.
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final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
def
toFuture(): Future[Seq[T]]
Collects the Observable results and converts to a scala.concurrent.Future.
Collects the Observable results and converts to a scala.concurrent.Future.
Automatically subscribes to the
Observable
and uses the collect method to aggregate the results.- returns
a future representation of the whole Observable
- Note
If the Observable is large then this will consume lots of memory! If the underlying Observable is infinite this Observable will never complete.
-
def
toString(): String
- Definition Classes
- AnyRef → Any
-
def
transform[S](mapFunction: (T) ⇒ S, errorMapFunction: (Throwable) ⇒ Throwable): Observable[S]
Creates a new Observable by applying the
resultFunction
function to each emitted result.Creates a new Observable by applying the
resultFunction
function to each emitted result. If there is an error andonError
is called theerrorFunction
function is applied to the failed result.- S
the resulting type of each item in the Observable
- mapFunction
function that transforms a each result of the receiver and passes the result to the returned Observable
- errorMapFunction
function that transforms a failure of the receiver into a failure of the returned observer
- returns
an Observable with transformed results and / or error.
-
final
def
wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
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final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
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- Annotations
- @throws( ... )
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final
def
wait(arg0: Long): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
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final
def
withFilter(p: (T) ⇒ Boolean): Observable[T]
Used by for-comprehensions.
-
def
zip[U](that: Observable[U]): Observable[(T, U)]
Zips the values of
this
andthat
Observable, and creates a new Observable holding the tuple of their results.Zips the values of
this
andthat
Observable, and creates a new Observable holding the tuple of their results.If
this
Observable fails, the resulting Observable is failed with the throwable stored inthis
. Otherwise, ifthat
Observable fails, the resulting Observable is failed with the throwable stored inthat
.It will only emit as many items as the number of items emitted by the source Observable that emits the fewest items.
- U
the type of the
that
Observable- that
the Observable to zip with
- returns
a new zipped Observable
This is the documentation for the MongoDB Scala driver.
Driver structure
The mongodb scala driver.
To get started you need a MongoClient instance, either from a connection string or via a org.mongodb.scala.MongoClientSettings.
Notable packages include: