updated Collection Download

Author: eisenbahnplatte

src/main/scala/org/dbpedia/databus/client/filehandling/SourceHandler.scala

@@ -6,6 +6,8 @@ import org.apache.http.client.ResponseHandler
 import org.apache.http.client.methods.HttpGet
 import org.apache.http.impl.client.{BasicResponseHandler, HttpClientBuilder}
 import org.dbpedia.databus.client.filehandling.download.Downloader
+import org.dbpedia.databus.client.sparql.QueryHandler
+import org.dbpedia.databus.client.sparql.queries.DatabusQueries
 import org.slf4j.LoggerFactory
 
 
@@ -53,13 +55,16 @@ object SourceHandler {
    */
   def handleQuery(query: String, target: File, cache: File, format: String, compression: String, overwrite: Boolean=false):Unit = {
 
-    val queryStr = {
+    var queryStr = {
       if (isCollection(query)) getQueryOfCollection(query)
       else query
     }
 
     printTask("query", queryStr, target.pathAsString)
 
+    //necessary due collection queries query the permament DBpedia URIs not the actual download links
+    if(isCollection(query)) queryStr = DatabusQueries.queryDownloadURLOfDatabusFiles(QueryHandler.executeDownloadQuery(queryStr))
+
     println("DOWNLOAD TOOL:")
 
     val allSHAs = Downloader.downloadWithQuery(queryStr, cache, overwrite)

src/main/scala/org/dbpedia/databus/client/filehandling/download/Downloader.scala

@@ -29,22 +29,24 @@ object Downloader {
     results.foreach(fileIRI => {
       val fileSHA = QueryHandler.getSHA256Sum(fileIRI)
 
-      if (overwrite) {
-        downloadFile(fileIRI, fileSHA, targetdir) match {
-          case Some(file: File) => allSHAs = allSHAs :+ fileSHA
-          case None => ""
-        }
-      }
-      else {
-        if (!FileUtil.checkIfFileInCache(targetdir, fileSHA)) {
+      if (fileSHA != "") {
+        if (overwrite) {
           downloadFile(fileIRI, fileSHA, targetdir) match {
-              case Some(file: File) => allSHAs = allSHAs :+ fileSHA
-              case None => ""
+            case Some(file: File) => allSHAs = allSHAs :+ fileSHA
+            case None => ""
           }
         }
         else {
-          println(s"$fileIRI --> already exists in Cache")
-          allSHAs = allSHAs :+ fileSHA
+          if (!FileUtil.checkIfFileInCache(targetdir, fileSHA)) {
+            downloadFile(fileIRI, fileSHA, targetdir) match {
+                case Some(file: File) => allSHAs = allSHAs :+ fileSHA
+                case None => ""
+            }
+          }
+          else {
+            println(s"$fileIRI --> already exists in Cache")
+            allSHAs = allSHAs :+ fileSHA
+          }
         }
       }
     })
@@ -80,7 +82,7 @@ object Downloader {
     if (!correctFileTransfer) {
       println("file download had issues")
       LoggerFactory.getLogger("Download-Logger").error(s"couldn't download file $url properly")
-      file.delete(true)
+      file.delete(swallowIOExceptions = true)
       return None
     }
 

src/main/scala/org/dbpedia/databus/client/sparql/QueryHandler.scala

@@ -2,19 +2,19 @@ package org.dbpedia.databus.client.sparql
 
 import java.io.FileNotFoundException
 import java.net.URL
-
 import better.files.File
 import org.apache.commons.io.FileUtils
 import org.apache.jena.JenaRuntime
 import org.apache.jena.query._
 import org.apache.jena.rdf.model.{Model, ModelFactory}
 import org.apache.jena.riot.{RDFDataMgr, RDFLanguages}
 import org.dbpedia.databus.client.sparql.queries.{DataIdQueries, DatabusQueries, MappingQueries}
-import org.slf4j.LoggerFactory
+import org.slf4j.{Logger, LoggerFactory}
 
 object QueryHandler {
 
   val service = "https://databus.dbpedia.org/repo/sparql"
+  val logger: Logger = LoggerFactory.getLogger(getClass)
 
   def executeQuery(queryString: String, model:Model = ModelFactory.createDefaultModel()): Seq[QuerySolution] = {
 
@@ -54,9 +54,15 @@ object QueryHandler {
   def getSHA256Sum(url: String): String = {
 
     val results = executeQuery(DatabusQueries.querySha256(url))
-    val sparqlVar = results.head.varNames().next()
 
-    results.head.getLiteral(sparqlVar).getString
+    try{
+      val sparqlVar = results.head.varNames().next()
+      results.head.getLiteral(sparqlVar).getString
+    } catch {
+      case noSuchElementException: NoSuchElementException =>
+        logger.error(s"No Sha Sum found for $url")
+        ""
+    }
 
   }
 

src/main/scala/org/dbpedia/databus/client/sparql/queries/DatabusQueries.scala

@@ -53,4 +53,17 @@ object DatabusQueries {
        |  ?mapping <http://tmp-namespace.org/databusFixRequired> ?file .
        |}
        |""".stripMargin
+
+  def queryDownloadURLOfDatabusFiles(files: Seq[String]): String = {
+    val databusFilesString = files.mkString("(<",">) (<",">)")
+    s"""
+       |PREFIX dcat:   <http://www.w3.org/ns/dcat#>
+       |
+       |SELECT DISTINCT ?file WHERE {
+       |  	VALUES (?databusfile) {$databusFilesString}
+       |  	?distribution ?o ?databusfile .
+       |	  ?distribution dcat:downloadURL ?file .
+       |}
+       |""".stripMargin
+  }
 }