[rygel] core,plugins: Add WritableContainer.remove_item()

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit 53efd4855cd2ac7d54fc3a61a89d58e0a4ed7c0a
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Wed Oct 27 20:55:23 2010 +0300

    core,plugins: Add WritableContainer.remove_item()
    
    Writable containers now support removal of (direct) child item, given its
    ID.

 .../rygel-media-export-db-container.vala           |    5 ++
 src/plugins/tracker/Makefile.am                    |    1 +
 .../rygel-tracker-category-all-container.vala      |   18 +++++++
 .../tracker/rygel-tracker-deletion-query.vala      |   54 ++++++++++++++++++++
 src/plugins/tracker/rygel-tracker-interfaces.vala  |    1 +
 src/rygel/rygel-writable-container.vala            |   14 +++++-
 6 files changed, 92 insertions(+), 1 deletions(-)
---
diff --git a/src/plugins/media-export/rygel-media-export-db-container.vala b/src/plugins/media-export/rygel-media-export-db-container.vala
index b145b6f..61f97a9 100644
--- a/src/plugins/media-export/rygel-media-export-db-container.vala
+++ b/src/plugins/media-export/rygel-media-export-db-container.vala
@@ -102,4 +102,9 @@ public class Rygel.MediaExport.DBContainer : MediaContainer, WritableContainer {
         item.id = MediaCache.get_id (File.new_for_uri (item.uris[0]));
         this.media_db.save_item (item);
     }
+
+    public async void remove_item (string id, Cancellable? cancellable)
+                                   throws Error {
+        this.media_db.remove_by_id (id);
+    }
 }
diff --git a/src/plugins/tracker/Makefile.am b/src/plugins/tracker/Makefile.am
index a112391..f93b5af 100644
--- a/src/plugins/tracker/Makefile.am
+++ b/src/plugins/tracker/Makefile.am
@@ -26,6 +26,7 @@ librygel_media_tracker_la_SOURCES = rygel-tracker-root-container.vala \
 				    rygel-tracker-category-all-container.vala \
 				    rygel-tracker-query.vala \
 				    rygel-tracker-selection-query.vala \
+				    rygel-tracker-deletion-query.vala \
 				    rygel-tracker-insertion-query.vala \
 				    rygel-tracker-query-triplet.vala \
 				    rygel-tracker-query-triplets.vala \
diff --git a/src/plugins/tracker/rygel-tracker-category-all-container.vala b/src/plugins/tracker/rygel-tracker-category-all-container.vala
index 555c885..63db5db 100644
--- a/src/plugins/tracker/rygel-tracker-category-all-container.vala
+++ b/src/plugins/tracker/rygel-tracker-category-all-container.vala
@@ -75,6 +75,18 @@ public class Rygel.Tracker.CategoryAllContainer : SearchContainer,
         this.updated ();
     }
 
+    public async void remove_item (string id, Cancellable? cancellable)
+                                   throws Error {
+        string parent_id;
+
+        var urn = this.get_item_info (id, out parent_id);
+
+        yield this.remove_entry_from_store (urn);
+
+        this.child_count--;
+        this.updated ();
+    }
+
     private async string create_entry_in_store (MediaItem item) throws Error {
         var category = this.item_factory.category;
         var query = new InsertionQuery (item, category);
@@ -83,5 +95,11 @@ public class Rygel.Tracker.CategoryAllContainer : SearchContainer,
 
         return query.id;
     }
+
+    private async void remove_entry_from_store (string id) throws Error {
+        var query = new DeletionQuery (id);
+
+        yield query.execute (this.resources);
+    }
 }
 
diff --git a/src/plugins/tracker/rygel-tracker-deletion-query.vala b/src/plugins/tracker/rygel-tracker-deletion-query.vala
new file mode 100644
index 0000000..bbcae22
--- /dev/null
+++ b/src/plugins/tracker/rygel-tracker-deletion-query.vala
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 20010 Nokia Corporation.
+ *
+ * Author: Zeeshan Ali <zeenix gmail com>
+ *
+ * This file is part of Rygel.
+ *
+ * Rygel is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Rygel is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+using Gee;
+
+/**
+ * Represents Tracker SPARQL Deletion query
+ */
+public class Rygel.Tracker.DeletionQuery : Query {
+    private string id;
+
+    public DeletionQuery (string id) {
+        var triplets = new QueryTriplets ();
+        triplets.add (new QueryTriplet ("<" + id + ">", "a", "rdfs:Resource"));
+
+        base (triplets);
+
+        this.id = id;
+    }
+
+    public override async void execute (ResourcesIface resources)
+                                        throws IOError {
+        var str = this.to_string ();
+
+        debug ("Executing SPARQL query: %s", str);
+
+        yield resources.sparql_update (str);
+
+        debug ("Deleted item '%s' from Tracker store", this.id);
+    }
+
+    public override string to_string () {
+        return "DELETE { " + base.to_string () + " }";
+    }
+}
diff --git a/src/plugins/tracker/rygel-tracker-interfaces.vala b/src/plugins/tracker/rygel-tracker-interfaces.vala
index 8479ed3..30ac613 100644
--- a/src/plugins/tracker/rygel-tracker-interfaces.vala
+++ b/src/plugins/tracker/rygel-tracker-interfaces.vala
@@ -30,6 +30,7 @@ public interface Rygel.Tracker.StatsIface : DBusProxy {
 public interface Rygel.Tracker.ResourcesIface: DBusProxy {
     public abstract async string[,] sparql_query (string query)
                                                   throws IOError;
+    public abstract async void sparql_update (string query) throws IOError;
     public abstract async HashTable<string,string>[,] sparql_update_blank (
                                         string query) throws IOError;
 }
diff --git a/src/rygel/rygel-writable-container.vala b/src/rygel/rygel-writable-container.vala
index 1c173e7..b020d44 100644
--- a/src/rygel/rygel-writable-container.vala
+++ b/src/rygel/rygel-writable-container.vala
@@ -27,7 +27,7 @@ using Gee;
 /**
  * Interface to be implemented by 'writable' container: ones that allow
  * creation, removal and editing of items directly under them. Currently, only
- * addition is supported.
+ * addition and removal is supported.
  *
  * In addition to implementing this interface, a writable container must also
  * provide one URI that points to a writable folder on a GIO supported
@@ -48,4 +48,16 @@ public interface Rygel.WritableContainer : MediaContainer {
      */
     public async abstract void add_item (MediaItem    item,
                                          Cancellable? cancellable) throws Error;
+
+    /**
+     * Remove an item directly under this container that has the ID @id.
+     *
+     * @param item The ID of the item to remove from this container
+     * @param cancellable optional cancellable for this operation
+     *
+     * return nothing.
+     *
+     */
+    public async abstract void remove_item (string id, Cancellable? cancellable)
+                                            throws Error;
 }