类型安全配置：如何迭代配置项

Question

In my Play application I've a configuration like this:

social {
    twitter {
        url="https://twitter.com"
        logo="images/twitter.png"
    }
    facebook {
        url="https://www.facebook.com"
        logo="images/facebook.png"
    }
}

Ho do I iterate over all the social entries to get url and logo for each entry?

<table border="0" cellspacing="0" cellpadding="2"><tr>
    @configuration.getConfig("social").map { config =>
        @for(item <- config.entrySet) {
           <td><a href="item.getString("url")">
           <img src="@routes.Assets.at("item.getString("logo")").absoluteURL()" width="24" height="24"/></a></td>
        }
    }
</table>

Of course, item.getString in the snippet here above does not work... it just shows what I'm trying to achieve.

The final objective would be to be able to add any further social url without having to modify the page template.

Answer 1

If you change the config to:

"social" : [
     {
        name="twitter",
        url="https://twitter.com",
        logo="images/twitter.png"
    },
    {
        name="facebook",
        url="https://www.facebook.com",
        logo="images/facebook.png"
    }
]

You could do it like this:

@(message: String)(implicit request: RequestHeader)
@import play.api.Play.current

<table border="0" cellspacing="0" cellpadding="2"><tr>
    @current.configuration.getConfigList("social").get.map { config =>
            <td><a href="@config.getString("url")">
            <img src="@routes.Assets.at(config.getString("logo").get).absoluteURL()" width="24" height="24"/></a></td>
        }
</table>

Answer 2

For posterity, here's another way to iterate over a nested config like you had. I prefer that format to the array one and I'd rather make my config cleaner than the code.

import collection.JavaConversions._
val socialConfig = ConfigFactory.load.getConfig("social")
socialConfig.root.map { case (name: String, configObject: ConfigObject) => 
    val config = configObject.toConfig
    println(config.getString("url"))
    println(config.getString("logo"))
}

I'm sure the OP could convert this into a Twirl template. That's about as clean as I can get it.

Answer 3

In case you you're using java,this might be a solution :

ConfigList socials = ConfigFactory().load.getList("social")

for (ConfigValue cv : socials) {
   Config c = ((ConfigObject)cv).toConfig();
   System.out.println(c.getString("url"));
   System.out.println(c.getString("logo"));
}

Answer 4

socialConfig.root.map does not work.

Here is my solution -

private val firstSegmentRE = """^(\w+)[\.*].*$""".r

// convert "aaa.bbb.ccc" to "aaa"
private def parseFirstSegment(fullPath: String) : Option[String] = {
  if (fullPath.contains("."))
    fullPath match {
      case firstSegmentRE(segment) => Some(segment)
      case _ => None
    }
  else
    Some(fullPath)
}

// for all keys in white list get a map of key -> config
protected def subConfigMap(config: Config, whiteList: List[String], 
configName: String) : ErrorOr[Map[String, Config]] = {
  // This will traverse the whole config and flatten down to the leaves..
  val leafKeys : List[String] =
    config.entrySet()
      .asScala
      .map(e => e.getKey)
      .toList
  // Remove all after the first dot
  val nextLevelKeys : List[String] =
    leafKeys.map(parseFirstSegment)
      .collect {
        case Some(firstSegment) => firstSegment
      }
      .distinct
  val keysToSearch = nextLevelKeys.filter(whiteList.contains)
  // we have a list of valid first level children
  // parse out subconfigs and convert to map
  keysToSearch.traverseErrorOr( key =>
    extractSubConfig(config, key, configName).map((key, _))
  )
  .map(_.toMap)
}

Where extractSubConfig is a method which produces an ERROR / Config (a scalaz disjunction) and traverseErrorOr is a method to traverse a list and either process all the elements or fail and return failed disjunction if failed at any point. This method can be done without scalaz, just posting an answer to help people if they want.

Answer 5

Since collection.JavaConversions has since been deprecated in favor of collection.JavaConverters (and this question is the top result on a search for how to iterate through a Typesafe Config in Scala), I wanted to suggest a more modern version of Cole's great answer:

import collection.JavaConverters._

val socialConfig = ConfigFactory.load.getConfig("social")

for ( (name: String, configObject: ConfigObject) <- socialConfig.root.asScala) {
    println(name) // prints "twitter" or "facebook"

    val config = configObject.toConfig
    println(config.getString("url"))
    println(config.getString("logo"))
}

To be clear, socialConfig.root.asScala yields a standard Scala Map[String, ConfigObject] and you can iterate over it however you'd like.

Answer 6

import collection.JavaConversions._
val socialConfig = ConfigFactory.load.getConfig("social")

val socialConfigMap = socialConfig
  .root()
  .entrySet()
  .asScala
  .map(socialEntry => {
    println(socialEntry.getKey)
    val socialEntryConfig = socialEntry.getValue.asInstanceOf[ConfigObject].toConfig

    println(socialEntryConfig.getString("url"))
    println(socialEntryConfig.getString("logo"))
  })

Answer 7

For the config mentioned originally in question:

social {
  twitter {
    url="https://twitter.com"
    logo="images/twitter.png"
  }
  facebook {
    url="https://www.facebook.com"
    logo="images/facebook.png"
  }
}

A solution in Java is:

val socialConfig = ConfigFactory.load.getConfig("social");
ConfigList socials = socialConfig.getList("social");

Map<String, Object> map = socials.root().unwrapped();
for (Map.Entry<String, Object> cv : map.entrySet()) {
  Map<String, String> c = (Map<String, String>)cv.getValue();
  System.out.println(cv.getKey());
  System.out.println(c.getOrDefault("url", ""));
  System.out.println(c.getOrDefault("logo", ""));
}