scala/scala

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AmirSarvestani

@AmirSarvestani

You can find Xml processing here as well. https://alvinalexander.com/scala/xml-parsing-xpath-extract-xml-tag-attributes

RoelofWobben

@RoelofWobben

can I improve this :

def earliestFilm:Option[String]  = directors.filter(_.lastName == "McTiernan").flatMap(_.films).sortWith(_.yearOfRelease < _.yearOfRelease).headOption.map(_.name)

I have to find the earliest film of McTiernan

AmirSarvestani

@AmirSarvestani

I think you can change filter with headoption fo find with contains

RoelofWobben

@RoelofWobben

@AmirSarvestani how do you see this

AmirSarvestani

@AmirSarvestani

directors.find(.lastName.contains("McTiernan")).flatMap(.films).sortWith(.yearOfRelease < .yearOfRelease).map(_.name)

Try this see if it works. If you use Intellij it also recommends you. See how it goes

Sindhuja

@Sindu__twitter

Hi, I want to initialize a mysql connection when the application starts and I think I need to do that in the Module.scala. Any ideas?

RoelofWobben

@RoelofWobben

@AmirSarvestani sorry , it do not work. I see a lot of type errors.

I use intelij and it recommends nothing at the moment

Dominic Egger

@GrafBlutwurst

@RoelofWobben you're looking for the oldest film?

Sorixelle

@Sorixelle

You could probably replace .sortWIth.headOption with a fold

vijendra singh

@viju0731_twitter

Batch entry was aborted. Call getNextException to see the cause

how do i call this in scala

any help

RoelofWobben

@RoelofWobben

@GrafBlutwurst yep, I misread , I have to find the year of the earliest film

so it solved it this way : def earliestFilm = mcTiernan.films.foldLeft(Int.MaxValue) { (current, film) => math.min(current, film.yearOfRelease)

with a hint of the book

but I have another problem that I cannot solve

I have to find the average score of the idbm Rating

so I did this :

val films = directors.flatMap(director => director.films)

    def averageScore:Int = films.foldLeft(0)((a, b) => a.imdbRating + b.imdbRating) / films.length

but now I see this type error :

Error:(60, 58) value imdbRating is not a member of Int
    def averageScore:Int = films.foldLeft(0)((a, b) => a.imdbRating + b.imdbRating) / films.length

Sorixelle

@Sorixelle

What type is films?

RoelofWobben

@RoelofWobben

so a is the acc that holds the answer ?

Martijn Hoekstra

@martijnhoekstra

try to annotate a and b with the types that you think they have

Sorixelle

@Sorixelle

Oh wait, hang on

a isn't the type you think it is

RoelofWobben

@RoelofWobben

Films is a list

Sorixelle

@Sorixelle

Remember, a is your accumulator, and b is the current object

RoelofWobben

@RoelofWobben

aha, that was I already suspected

vijendra singh

@viju0731_twitter

@viju0731_twitter
Batch entry was aborted. Call getNextException to see the cause
how do i call this in scala
any help

getting ths error

how to call getNextException here

Batch Entry 0 insert into PGSQL-Call getNextException to see the cause

this is exact error I am getting

i want to see the real cause why it is failing to update the batch using scala

Sorixelle

@Sorixelle

Hard to help without any context - where are you seeing this error? What are you doing to cause it?

vijendra singh

@viju0731_twitter

i am trying to make call to postgres from scala file

when i am trying to write the data in postgres getting this error

RoelofWobben

@RoelofWobben

Thanks, I think it's time to find out how I can see the type of something in intelij

vijendra singh

@viju0731_twitter

java.sql.BatchUpdateException: Batch entry 0 INSERT INTO

Dominic Egger

@GrafBlutwurst

@RoelofWobben scala is so nice as to put some convinience methods on specific lists. List[Int] has a sum method e.g. List(1,2,3).sum. Though technically I think a foldLeft where you sum and count at the same time is more efficient

Sorixelle

@Sorixelle

@RoelofWobben If you hover over something with Ctrl (or Cmd on macOS), it shows you the type signature

Dominic Egger

@GrafBlutwurst

i think the keyboard shortcut is ctrl+p for showing the signature of a parameter list under the cursor. I'd also recommend rebinding "type info" action in intellij to something better reachable

RoelofWobben

@RoelofWobben

@GrafBlutwurst so I can do something like (films.map(_.idbmRating).sum ?

to count all ratings

Sorixelle

@Sorixelle

That would give you the total of all ratings, yes

sum is equivalent to reduce(_ + _), or fold(0)(_ + _)

Dominic Egger

@GrafBlutwurst

I think .sum etc exits for all T : Numeric

Sorixelle

@Sorixelle

where fold can be either foldLeft or foldRight

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