prevent double linking of datasets and dataverses #7259

src/main/java/edu/harvard/iq/dataverse/engine/command/impl/LinkDatasetCommand.java

@@ -19,7 +19,9 @@
 import edu.harvard.iq.dataverse.util.BundleUtil;
 import java.io.IOException;
 import java.sql.Timestamp;
+import java.util.ArrayList;
 import java.util.Date;
+import java.util.List;
 import org.apache.solr.client.solrj.SolrServerException;
 
 /**
@@ -50,6 +52,13 @@ public DatasetLinkingDataverse execute(CommandContext ctxt) throws CommandExcept
         if (linkedDataset.getOwner().getOwners().contains(linkingDataverse)) {
             throw new IllegalCommandException(BundleUtil.getStringFromBundle("dataset.link.not.to.parent.dataverse"), this);
         }
+        List<Dataverse> existingLinksToDataverses = new ArrayList<>();
+        for (DatasetLinkingDataverse datasetLinkingDataverse : linkedDataset.getDatasetLinkingDataverses()) {
+            existingLinksToDataverses.add(datasetLinkingDataverse.getLinkingDataverse());
+        }
+        if (existingLinksToDataverses.contains(linkingDataverse)) {
+            throw new IllegalCommandException(BundleUtil.getStringFromBundle("dataset.link.not.already.linked"), this);
+        }
 
         DatasetLinkingDataverse datasetLinkingDataverse = new DatasetLinkingDataverse();
         datasetLinkingDataverse.setDataset(linkedDataset);

src/main/java/propertyFiles/Bundle.properties

@@ -1314,6 +1314,7 @@ dataset.link.not.to.owner=Can't link a dataset to its dataverse
 dataset.link.not.to.parent.dataverse=Can't link a dataset to its parent dataverses
 dataset.link.not.published=Can't link a dataset that has not been published
 dataset.link.not.available=Can't link a dataset that has not been published or is not harvested
+dataset.link.not.already.linked=Can't link a dataset that has already been linked to this dataverse
 dataset.email.datasetContactTitle=Contact Dataset Owner
 dataset.email.hiddenMessage= 
 dataset.email.messageSubject=Test Message Subject

src/test/java/edu/harvard/iq/dataverse/api/MoveIT.java

@@ -254,6 +254,12 @@ public void testMoveLinkedDataset() {
         linkDataset.then().assertThat()
                 .statusCode(OK.getStatusCode());
 
+        // A dataset cannot be linked to the same dataverse again.
+        Response tryToLinkAgain = UtilIT.linkDataset(datasetPid, dataverse2Alias, superuserApiToken);
+        tryToLinkAgain.prettyPrint();
+        tryToLinkAgain.then().assertThat()
+                .statusCode(FORBIDDEN.getStatusCode());
+
         Response getLinksBefore = UtilIT.getDatasetLinks(datasetPid, superuserApiToken);
         getLinksBefore.prettyPrint();
         getLinksBefore.then().assertThat()