Retrieve value from item wrapped in a Future[Option[Item]] [closed]

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I have a function like this

def findById(id: UUID): Future[Option[Item]]

case class Item(subject: String)

Now I want to retrieve the subject if the item exists else I want the subject to be empty string.

val subject: Future[String] = repository
 .findById(someId)
 .map(_.map(i => i.subject))
 .map(_.getOrElse(""))

subject.foreach(doSomething)

Am I doing it right or is there a better way in Scala without frameworks like Scalaz.

edited May 23 at 9:22

asked May 23 at 8:24

uraza

865

closed as off-topic by Billal BEGUERADJ, t3chb0t, Stephen Rauch, Sam Onela, Dannnno May 23 at 13:46

This question appears to be off-topic. The users who voted to close gave this specific reason:

"Lacks concrete context: Code Review requires concrete code from a project, with sufficient context for reviewers to understand how that code is used. Pseudocode, stub code, hypothetical code, obfuscated code, and generic best practices are outside the scope of this site." â€“ Billal BEGUERADJ, t3chb0t, Stephen Rauch, Sam Onela, Dannnno

If this question can be reworded to fit the rules in the help center, please edit the question.

Welcome to Code Review! This question is incomplete. To help reviewers give you better answers, please add sufficient context to your question. The more you tell us about what your code does and what the purpose of doing that is, the easier it will be for reviewers to help you. Questions should include a description of what the code does
â€“Â Dannnno
May 23 at 13:45

add a commentÂ |Â

up vote
0
down vote

favorite

I have a function like this

def findById(id: UUID): Future[Option[Item]]

case class Item(subject: String)

Now I want to retrieve the subject if the item exists else I want the subject to be empty string.

val subject: Future[String] = repository
 .findById(someId)
 .map(_.map(i => i.subject))
 .map(_.getOrElse(""))

subject.foreach(doSomething)

Am I doing it right or is there a better way in Scala without frameworks like Scalaz.

edited May 23 at 9:22

asked May 23 at 8:24

uraza

865

closed as off-topic by Billal BEGUERADJ, t3chb0t, Stephen Rauch, Sam Onela, Dannnno May 23 at 13:46

This question appears to be off-topic. The users who voted to close gave this specific reason:

"Lacks concrete context: Code Review requires concrete code from a project, with sufficient context for reviewers to understand how that code is used. Pseudocode, stub code, hypothetical code, obfuscated code, and generic best practices are outside the scope of this site." â€“ Billal BEGUERADJ, t3chb0t, Stephen Rauch, Sam Onela, Dannnno

If this question can be reworded to fit the rules in the help center, please edit the question.

Welcome to Code Review! This question is incomplete. To help reviewers give you better answers, please add sufficient context to your question. The more you tell us about what your code does and what the purpose of doing that is, the easier it will be for reviewers to help you. Questions should include a description of what the code does
â€“Â Dannnno
May 23 at 13:45

add a commentÂ |Â

up vote
0
down vote

favorite

I have a function like this

def findById(id: UUID): Future[Option[Item]]

case class Item(subject: String)

Now I want to retrieve the subject if the item exists else I want the subject to be empty string.

val subject: Future[String] = repository
 .findById(someId)
 .map(_.map(i => i.subject))
 .map(_.getOrElse(""))

subject.foreach(doSomething)

Am I doing it right or is there a better way in Scala without frameworks like Scalaz.

edited May 23 at 9:22

asked May 23 at 8:24

uraza

865

I have a function like this

def findById(id: UUID): Future[Option[Item]]

case class Item(subject: String)

Now I want to retrieve the subject if the item exists else I want the subject to be empty string.

val subject: Future[String] = repository
 .findById(someId)
 .map(_.map(i => i.subject))
 .map(_.getOrElse(""))

subject.foreach(doSomething)

Am I doing it right or is there a better way in Scala without frameworks like Scalaz.

edited May 23 at 9:22

asked May 23 at 8:24

uraza

865

edited May 23 at 9:22

asked May 23 at 8:24

uraza

865

asked May 23 at 8:24

uraza

865

asked May 23 at 8:24

uraza

865

closed as off-topic by Billal BEGUERADJ, t3chb0t, Stephen Rauch, Sam Onela, Dannnno May 23 at 13:46

This question appears to be off-topic. The users who voted to close gave this specific reason:

"Lacks concrete context: Code Review requires concrete code from a project, with sufficient context for reviewers to understand how that code is used. Pseudocode, stub code, hypothetical code, obfuscated code, and generic best practices are outside the scope of this site." â€“ Billal BEGUERADJ, t3chb0t, Stephen Rauch, Sam Onela, Dannnno

If this question can be reworded to fit the rules in the help center, please edit the question.

closed as off-topic by Billal BEGUERADJ, t3chb0t, Stephen Rauch, Sam Onela, Dannnno May 23 at 13:46

This question appears to be off-topic. The users who voted to close gave this specific reason:

"Lacks concrete context: Code Review requires concrete code from a project, with sufficient context for reviewers to understand how that code is used. Pseudocode, stub code, hypothetical code, obfuscated code, and generic best practices are outside the scope of this site." â€“ Billal BEGUERADJ, t3chb0t, Stephen Rauch, Sam Onela, Dannnno

If this question can be reworded to fit the rules in the help center, please edit the question.

Welcome to Code Review! This question is incomplete. To help reviewers give you better answers, please add sufficient context to your question. The more you tell us about what your code does and what the purpose of doing that is, the easier it will be for reviewers to help you. Questions should include a description of what the code does
â€“Â Dannnno
May 23 at 13:45

add a commentÂ |Â

Welcome to Code Review! This question is incomplete. To help reviewers give you better answers, please add sufficient context to your question. The more you tell us about what your code does and what the purpose of doing that is, the easier it will be for reviewers to help you. Questions should include a description of what the code does
â€“Â Dannnno
May 23 at 13:45

Welcome to Code Review! This question is incomplete. To help reviewers give you better answers, please add sufficient context to your question. The more you tell us about what your code does and what the purpose of doing that is, the easier it will be for reviewers to help you. Questions should include a description of what the code does
â€“Â Dannnno
May 23 at 13:45

add a commentÂ |Â

2 Answers
2

active

oldest

votes

up vote
1
down vote

It's better that you are staying in the Futures domain, no longer trying to unwrap to String.

It's not so easy to follow all of the underscore-based function expressions. I'd try something like...

val subject: Future[String] = 
 repository.findById(someId) map mbItem =>
 mbItem match 
 case Some( item ) => item.subject
 case None => ""

answered May 23 at 10:28

Steve Waldman

1193

add a commentÂ |Â

up vote
0
down vote

It's best to stay in the Futures domain if you can. But if you absolutely need out, you need to await to be sure a result has been computed.

val result = Await.result(repository.findById(someId), Duration.Inf)
val subject = result match 
 case Some( item ) => item.subject
 case None => ""

(If you prefer not to wait, but you are cool with the computation maybe not having completed, see the value method of Future.)

answered May 23 at 8:51

Steve Waldman

1193

I thought the map applies a function on the future when it completes. Isn't the Await.result also blocking?
â€“Â uraza
May 23 at 9:19

My apologies, sir. I forgot to add a foreach at the end. See edited post.
â€“Â uraza
May 23 at 9:22

yes, await is blocking. but in the original version of your post subject was a String rather than Future[String], so you would have had to block to safely unwrap. now that what you want is Future[String], you can stay in the Futures domain with map(...) etc.
â€“Â Steve Waldman
May 23 at 10:20

add a commentÂ |Â

2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

up vote
1
down vote

It's better that you are staying in the Futures domain, no longer trying to unwrap to String.

It's not so easy to follow all of the underscore-based function expressions. I'd try something like...

val subject: Future[String] = 
 repository.findById(someId) map mbItem =>
 mbItem match 
 case Some( item ) => item.subject
 case None => ""

answered May 23 at 10:28

Steve Waldman

1193

add a commentÂ |Â

up vote
1
down vote

It's better that you are staying in the Futures domain, no longer trying to unwrap to String.

It's not so easy to follow all of the underscore-based function expressions. I'd try something like...

val subject: Future[String] = 
 repository.findById(someId) map mbItem =>
 mbItem match 
 case Some( item ) => item.subject
 case None => ""

answered May 23 at 10:28

Steve Waldman

1193

add a commentÂ |Â

up vote
1
down vote

It's better that you are staying in the Futures domain, no longer trying to unwrap to String.

It's not so easy to follow all of the underscore-based function expressions. I'd try something like...

val subject: Future[String] = 
 repository.findById(someId) map mbItem =>
 mbItem match 
 case Some( item ) => item.subject
 case None => ""

answered May 23 at 10:28

Steve Waldman

1193

It's better that you are staying in the Futures domain, no longer trying to unwrap to String.

It's not so easy to follow all of the underscore-based function expressions. I'd try something like...

val subject: Future[String] = 
 repository.findById(someId) map mbItem =>
 mbItem match 
 case Some( item ) => item.subject
 case None => ""

answered May 23 at 10:28

Steve Waldman

1193

answered May 23 at 10:28

Steve Waldman

1193

answered May 23 at 10:28

Steve Waldman

1193

answered May 23 at 10:28

Steve Waldman

1193

add a commentÂ |Â

up vote
0
down vote

It's best to stay in the Futures domain if you can. But if you absolutely need out, you need to await to be sure a result has been computed.

val result = Await.result(repository.findById(someId), Duration.Inf)
val subject = result match 
 case Some( item ) => item.subject
 case None => ""

(If you prefer not to wait, but you are cool with the computation maybe not having completed, see the value method of Future.)

answered May 23 at 8:51

Steve Waldman

1193

I thought the map applies a function on the future when it completes. Isn't the Await.result also blocking?
â€“Â uraza
May 23 at 9:19

My apologies, sir. I forgot to add a foreach at the end. See edited post.
â€“Â uraza
May 23 at 9:22

yes, await is blocking. but in the original version of your post subject was a String rather than Future[String], so you would have had to block to safely unwrap. now that what you want is Future[String], you can stay in the Futures domain with map(...) etc.
â€“Â Steve Waldman
May 23 at 10:20

add a commentÂ |Â

up vote
0
down vote

It's best to stay in the Futures domain if you can. But if you absolutely need out, you need to await to be sure a result has been computed.

val result = Await.result(repository.findById(someId), Duration.Inf)
val subject = result match 
 case Some( item ) => item.subject
 case None => ""

(If you prefer not to wait, but you are cool with the computation maybe not having completed, see the value method of Future.)

answered May 23 at 8:51

Steve Waldman

1193

I thought the map applies a function on the future when it completes. Isn't the Await.result also blocking?
â€“Â uraza
May 23 at 9:19

My apologies, sir. I forgot to add a foreach at the end. See edited post.
â€“Â uraza
May 23 at 9:22

yes, await is blocking. but in the original version of your post subject was a String rather than Future[String], so you would have had to block to safely unwrap. now that what you want is Future[String], you can stay in the Futures domain with map(...) etc.
â€“Â Steve Waldman
May 23 at 10:20

add a commentÂ |Â

up vote
0
down vote

It's best to stay in the Futures domain if you can. But if you absolutely need out, you need to await to be sure a result has been computed.

val result = Await.result(repository.findById(someId), Duration.Inf)
val subject = result match 
 case Some( item ) => item.subject
 case None => ""

(If you prefer not to wait, but you are cool with the computation maybe not having completed, see the value method of Future.)

answered May 23 at 8:51

Steve Waldman

1193

It's best to stay in the Futures domain if you can. But if you absolutely need out, you need to await to be sure a result has been computed.

val result = Await.result(repository.findById(someId), Duration.Inf)
val subject = result match 
 case Some( item ) => item.subject
 case None => ""

(If you prefer not to wait, but you are cool with the computation maybe not having completed, see the value method of Future.)

answered May 23 at 8:51

Steve Waldman

1193

answered May 23 at 8:51

Steve Waldman

1193

answered May 23 at 8:51

Steve Waldman

1193

answered May 23 at 8:51

Steve Waldman

1193

I thought the map applies a function on the future when it completes. Isn't the Await.result also blocking?
â€“Â uraza
May 23 at 9:19

My apologies, sir. I forgot to add a foreach at the end. See edited post.
â€“Â uraza
May 23 at 9:22

yes, await is blocking. but in the original version of your post subject was a String rather than Future[String], so you would have had to block to safely unwrap. now that what you want is Future[String], you can stay in the Futures domain with map(...) etc.
â€“Â Steve Waldman
May 23 at 10:20

add a commentÂ |Â

I thought the map applies a function on the future when it completes. Isn't the Await.result also blocking?
â€“Â uraza
May 23 at 9:19

My apologies, sir. I forgot to add a foreach at the end. See edited post.
â€“Â uraza
May 23 at 9:22

yes, await is blocking. but in the original version of your post subject was a String rather than Future[String], so you would have had to block to safely unwrap. now that what you want is Future[String], you can stay in the Futures domain with map(...) etc.
â€“Â Steve Waldman
May 23 at 10:20

I thought the map applies a function on the future when it completes. Isn't the Await.result also blocking?
â€“Â uraza
May 23 at 9:19

My apologies, sir. I forgot to add a foreach at the end. See edited post.
â€“Â uraza
May 23 at 9:22

yes, await is blocking. but in the original version of your post subject was a String rather than Future[String], so you would have had to block to safely unwrap. now that what you want is Future[String], you can stay in the Futures domain with map(...) etc.
â€“Â Steve Waldman
May 23 at 10:20

add a commentÂ |Â

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