Added "Add example entry" and "Import existing PDFs" when a library is empty (#12741)

* Add placeholder with "Add Example Entry" for empty library
-Ensures button is hidden when entries exist but are filtered
-Add listeners to track database and table entry changes

* Updated code based on draft review ( Import pdf pending)
-used localization
-added styles for button

* Added function for Import existing PDFs
-checks if directory exists
-triggers search for unlinked files ( if directory exists )
-Shows notification and open library properties ( if directory doesn't exist)

* updated CHANGELOG.md

* Fixed localization issues and checkstyle

* Fixed localization issues

* submodules changes

* roll back .gitmodules

* Added comment at the right place

* Resolved Review Comments
- Removed Unnecessary comments
- Used withField for BibEntry instead of setField

* Removed Exclamation mark , should be avoided in UI messages.
-updating with period

* -Refactored function name to importPdfs
-Added focus for library-specific file directory

* -Refactored importPDFs to follow fail fast principles
-Removed Unused Localization keys
-Updated to lambda for better readability

* -rewriteRun changes

* -Resolved Review Changes .
-Label Style Changes

---------

Co-authored-by: Christoph <[email protected]>

Author: sanjyot242

CHANGELOG.md

@@ -11,6 +11,7 @@ Note that this project **does not** adhere to [Semantic Versioning](https://semv
 
 ### Added
 
+- We added buttons "Add example entry" and "Import existing PDFs" when a library is empty, making it easier for new users to get started. [#12662](https://github.com/JabRef/jabref/issues/12662)
 - In the Open/LibreOffice integration, we added the provision to modify the bibliography title and its format for CSL styles, in the "Select style" dialog. [#12663](https://github.com/JabRef/jabref/issues/12663)
 - We added a new Welcome tab which shows a welcome screen if no database is open. [#12272](https://github.com/JabRef/jabref/issues/12272)
 - We added <kbd>F5</kbd> as a shortcut key for fetching data and <kbd>Alt+F</kbd> as a shortcut for looking up data using DOI. [#11802](https://github.com/JabRef/jabref/issues/11802)

src/main/java/org/jabref/gui/Base.css

@@ -2496,3 +2496,10 @@ journalInfo .grid-cell-b {
 .refresh {
     -fx-background-color: transparent;
 }
+
+.text-button-blue{
+    -fx-background-color: transparent;
+    -fx-text-fill: -jr-theme;
+    -fx-font-size: 1.25em;
+    -fx-border-color: transparent;
+}

src/main/java/org/jabref/gui/fieldeditors/LinkedFileViewModel.java

@@ -294,7 +294,7 @@ public void moveToDefaultDirectory() {
         // Get target folder
         Optional<Path> fileDir = databaseContext.getFirstExistingFileDir(preferences.getFilePreferences());
         if (fileDir.isEmpty()) {
-            dialogService.showErrorDialogAndWait(Localization.lang("Move file"), Localization.lang("File directory is not set or does not exist!"));
+            dialogService.showErrorDialogAndWait(Localization.lang("Move file"), Localization.lang("File directory is not set or does not exist."));
             return;
         }
 

src/main/java/org/jabref/gui/libraryproperties/general/GeneralPropertiesView.java

@@ -2,6 +2,7 @@
 
 import java.nio.charset.Charset;
 
+import javafx.application.Platform;
 import javafx.fxml.FXML;
 import javafx.scene.control.ComboBox;
 import javafx.scene.control.TextField;
@@ -57,6 +58,8 @@ public void initialize() {
         librarySpecificFileDirectory.textProperty().bindBidirectional(viewModel.librarySpecificDirectoryPropertyProperty());
         userSpecificFileDirectory.textProperty().bindBidirectional(viewModel.userSpecificFileDirectoryProperty());
         laTexFileDirectory.textProperty().bindBidirectional(viewModel.laTexFileDirectoryProperty());
+
+        Platform.runLater(()-> librarySpecificFileDirectory.requestFocus());
     }
 
     @FXML

src/main/java/org/jabref/gui/maintable/MainTable.java

@@ -12,6 +12,9 @@
 
 import javafx.collections.ListChangeListener;
 import javafx.css.PseudoClass;
+import javafx.geometry.Pos;
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
 import javafx.scene.control.SelectionMode;
 import javafx.scene.control.TableColumn;
 import javafx.scene.control.TableRow;
@@ -24,6 +27,8 @@
 import javafx.scene.input.MouseDragEvent;
 import javafx.scene.input.MouseEvent;
 import javafx.scene.input.TransferMode;
+import javafx.scene.layout.HBox;
+import javafx.scene.layout.VBox;
 
 import org.jabref.architecture.AllowedToUseClassGetResource;
 import org.jabref.gui.ClipBoardManager;
@@ -35,10 +40,12 @@
 import org.jabref.gui.actions.StandardActions;
 import org.jabref.gui.edit.EditAction;
 import org.jabref.gui.externalfiles.ExternalFilesEntryLinker;
+import org.jabref.gui.externalfiles.FindUnlinkedFilesAction;
 import org.jabref.gui.externalfiles.ImportHandler;
 import org.jabref.gui.importer.fetcher.LookupIdentifierAction;
 import org.jabref.gui.keyboard.KeyBinding;
 import org.jabref.gui.keyboard.KeyBindingRepository;
+import org.jabref.gui.libraryproperties.LibraryPropertiesAction;
 import org.jabref.gui.maintable.columns.LibraryColumn;
 import org.jabref.gui.maintable.columns.MainTableColumn;
 import org.jabref.gui.mergeentries.MergeWithFetchedEntryAction;
@@ -53,11 +60,14 @@
 import org.jabref.logic.citationstyle.CitationStyleOutputFormat;
 import org.jabref.logic.importer.WebFetchers;
 import org.jabref.logic.journals.JournalAbbreviationRepository;
+import org.jabref.logic.l10n.Localization;
 import org.jabref.logic.util.TaskExecutor;
 import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.model.entry.BibEntry;
 import org.jabref.model.entry.BibEntryTypesManager;
+import org.jabref.model.entry.field.StandardField;
 import org.jabref.model.entry.identifier.DOI;
+import org.jabref.model.entry.types.StandardEntryType;
 
 import com.airhacks.afterburner.injection.Injector;
 import org.slf4j.Logger;
@@ -193,6 +203,32 @@ public MainTable(MainTableDataModel model,
 
         this.setItems(model.getEntriesFilteredAndSorted());
 
+        Button addExampleButton = new Button(Localization.lang("Add example entry"));
+        addExampleButton.getStyleClass().add("text-button-blue");
+        addExampleButton.setOnAction(event -> {
+            BibEntry entry = addExampleEntry();
+            libraryTab.showAndEdit(entry);
+        });
+
+        Button importPdfsButton = new Button(Localization.lang("Import existing PDFs"));
+        importPdfsButton.getStyleClass().add("text-button-blue");
+        importPdfsButton.setOnAction(event -> importPdfs());
+
+        Label noContentLabel = new Label(Localization.lang("No content in table"));
+        noContentLabel.getStyleClass().add("welcome-header-label");
+
+        HBox buttonBox = new HBox(20, addExampleButton, importPdfsButton);
+        buttonBox.setAlignment(Pos.CENTER);
+
+        VBox placeholderBox = new VBox(15, noContentLabel, buttonBox);
+        placeholderBox.setAlignment(Pos.CENTER);
+
+        updatePlaceholder(placeholderBox);
+
+        database.getDatabase().getEntries().addListener((ListChangeListener<BibEntry>) change -> updatePlaceholder(placeholderBox));
+
+        this.getItems().addListener((ListChangeListener<BibEntryTableViewModel>) change -> updatePlaceholder(placeholderBox));
+
         // Enable sorting
         // Workaround for a JavaFX bug: https://bugs.openjdk.org/browse/JDK-8301761 (The sorting of the SortedList can become invalid)
         // The default comparator of the SortedList does not consider the insertion index of entries that are equal according to the comparator.
@@ -538,4 +574,44 @@ private Optional<BibEntryTableViewModel> findEntry(BibEntry entry) {
     public void setCitationMergeMode(boolean citationMerge) {
         this.citationMergeMode = citationMerge;
     }
+
+    private void updatePlaceholder(VBox placeholderBox) {
+       if (database.getDatabase().getEntries().isEmpty()) {
+           this.setPlaceholder(placeholderBox);
+       } else {
+           this.setPlaceholder(null);
+       }
+    }
+
+    private BibEntry addExampleEntry() {
+        BibEntry exampleEntry = new BibEntry(StandardEntryType.Article)
+                .withField(StandardField.AUTHOR, "Oliver Kopp and Carl Christian Snethlage and Christoph Schwentker").withField(StandardField.TITLE, "JabRef: BibTeX-based literature management software")
+                .withField(StandardField.JOURNAL, "TUGboat")
+                .withField(StandardField.VOLUME, "44")
+                .withField(StandardField.NUMBER, "3")
+                .withField(StandardField.PAGES, "441--447")
+                .withField(StandardField.DOI, "10.47397/tb/44-3/tb138kopp-jabref")
+                .withField(StandardField.ISSN, "0896-3207")
+                .withField(StandardField.ISSUE, "138")
+                .withField(StandardField.YEAR, "2023");
+
+        database.getDatabase().insertEntry(exampleEntry);
+        return exampleEntry;
+    }
+
+    private void importPdfs() {
+        List<Path> fileDirectories = database.getFileDirectories(filePreferences);
+
+        if (fileDirectories.isEmpty()) {
+            dialogService.notify(
+                    Localization.lang("File directory is not set or does not exist.")
+            );
+            LibraryPropertiesAction libraryPropertiesAction = new LibraryPropertiesAction(stateManager);
+            libraryPropertiesAction.execute();
+            return;
+        }
+
+        FindUnlinkedFilesAction findUnlinkedFilesAction = new FindUnlinkedFilesAction(dialogService, stateManager);
+        findUnlinkedFilesAction.execute();
+    }
 }

src/main/resources/l10n/JabRef_en.properties

@@ -2748,7 +2748,7 @@ Clear\ history=Clear history
 
 File=File
 file=file
-File\ directory\ is\ not\ set\ or\ does\ not\ exist\!=File directory is not set or does not exist!
+File\ directory\ is\ not\ set\ or\ does\ not\ exist.=File directory is not set or does not exist.
 File\ exists=File exists
 File\ not\ found=File not found
 
@@ -2879,6 +2879,11 @@ Editor\ related=Editor related
 Title\ related=Title related
 Entry\ fields=Entry fields
 
+Add\ example\ entry=Add example entry
+No\ content\ in\ table=No content in table
+Import\ existing\ PDFs=Import existing PDFs
+
+
 No\ recent\ libraries=No recent libraries
 Recent=Recent
 Start=Start