switch to viewmodel for feeds/cats

8 files changed, 311 insertions, 276 deletions

diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/ApiLoader.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/ApiLoader.java
deleted file mode 100755
index 5cba0ed1..00000000
--- a/org.fox.ttrss/src/main/java/org/fox/ttrss/ApiLoader.java
+++ /dev/null
@@ -1,84 +0,0 @@
-package org.fox.ttrss;
-
-import android.content.Context;
-
-import androidx.loader.content.AsyncTaskLoader;
-
-import com.google.gson.JsonElement;
-
-import org.fox.ttrss.ApiCommon.ApiError;
-
-import java.util.HashMap;
-
-public class ApiLoader extends AsyncTaskLoader<JsonElement> implements ApiCommon.ApiCaller {
-	private final String TAG = this.getClass().getSimpleName();
-
-	private final int m_responseCode = 0;
-	protected String m_responseMessage;
-	private int m_apiStatusCode = 0;
-
-	private final Context m_context;
-	private String m_lastErrorMessage;
-	private ApiError m_lastError;
-	private final HashMap<String,String> m_params;
-	private JsonElement m_data;
-
-	ApiLoader(Context context, HashMap<String, String> params) {
-		super(context);
-
-		m_context = context;
-		m_lastError = ApiError.UNKNOWN_ERROR;
-		m_params = params;
-	}
-
-	@Override
-	protected void onStartLoading() {
-		if (m_data != null) {
-			deliverResult(m_data);
-		} else {
-			forceLoad();
-		}
-	}
-
-	@Override
-	public void deliverResult(JsonElement data) {
-		m_data = data;
-
-		super.deliverResult(data);
-	}
-
-	public int getErrorMessage() {
-		return ApiCommon.getErrorMessage(m_lastError);
-	}
-
-	ApiError getLastError() {
-		return m_lastError;
-	}
-
-	String getLastErrorMessage() {
-		return m_lastErrorMessage;
-	}
-
-	@Override
-	public JsonElement loadInBackground() {
-		return ApiCommon.performRequest(m_context, m_params, this);
-	}
-
-	@Override
-	public void setStatusCode(int statusCode) {
-		m_apiStatusCode = statusCode;
-	}
-
-	@Override
-	public void setLastError(ApiError lastError) {
-		m_lastError = lastError;
-	}
-
-	@Override
-	public void setLastErrorMessage(String message) {
-		m_lastErrorMessage = message;
-	}
-
-	@Override
-	public void notifyProgress(int progress) {	}
-}
diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/Application.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/Application.java
index 75542e3c..11e32bcf 100755
--- a/org.fox.ttrss/src/main/java/org/fox/ttrss/Application.java
+++ b/org.fox.ttrss/src/main/java/org/fox/ttrss/Application.java
@@ -11,9 +11,6 @@ import java.util.HashMap;
 import java.util.LinkedHashMap;
 
 public class Application extends android.app.Application {
-	public static final int LOADER_HEADLINES = 0;
-	public static final int LOADER_FEEDS = 1;
-	public static final int LOADER_CATS = 2;
 
 	private static Application m_singleton;
 
diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/ArticleModel.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/ArticleModel.java
index f4deb372..2a6b4b3e 100644
--- a/org.fox.ttrss/src/main/java/org/fox/ttrss/ArticleModel.java
+++ b/org.fox.ttrss/src/main/java/org/fox/ttrss/ArticleModel.java
@@ -47,7 +47,7 @@ public class ArticleModel extends AndroidViewModel implements ApiCommon.ApiCalle
     private int m_resizeWidth;
     private boolean m_append;
     private boolean m_lazyLoadEnabled = true;
-    private boolean m_loadingInProgress;
+    private MutableLiveData<Boolean> m_isLoading = new MutableLiveData<>(Boolean.valueOf(false));
     private ExecutorService m_executor;
     private Handler m_mainHandler = new Handler(Looper.getMainLooper());
     private MutableLiveData<Long> m_lastUpdate = new MutableLiveData<>(Long.valueOf(0));
@@ -91,7 +91,7 @@ public class ArticleModel extends AndroidViewModel implements ApiCommon.ApiCalle
             m_feed = feed;
 
             loadInBackground();
-        } else if (feed != m_feed || m_lazyLoadEnabled && !m_loadingInProgress) {
+        } else if (feed != m_feed || m_lazyLoadEnabled || !m_isLoading.getValue()) {
             m_append = true;
             m_feed = feed;
 
@@ -106,7 +106,7 @@ public class ArticleModel extends AndroidViewModel implements ApiCommon.ApiCalle
 
         ArticleList articlesWork = new ArticleList(m_articles.getValue());
 
-        m_loadingInProgress = true;
+        m_isLoading.postValue(true);
 
         final int skip = getSkip(m_append, articlesWork);
         final boolean allowForceUpdate = org.fox.ttrss.Application.getInstance().getApiLevel() >= 9 &&
@@ -212,7 +212,7 @@ public class ArticleModel extends AndroidViewModel implements ApiCommon.ApiCalle
                         }
 
                         m_offset += m_amountLoaded;
-                        m_loadingInProgress = false;
+                        m_isLoading.postValue(false);
 
                         Log.d(TAG, this + " loaded headlines=" + m_amountLoaded + " resultingLocalSize=" + articlesWork.size());
                     }
@@ -227,7 +227,7 @@ public class ArticleModel extends AndroidViewModel implements ApiCommon.ApiCalle
             });
         });
 
-        m_loadingInProgress = false;
+        m_isLoading.postValue(false);
 
     }
 
@@ -299,7 +299,7 @@ public class ArticleModel extends AndroidViewModel implements ApiCommon.ApiCalle
         return m_offset;
     }
 
-    public boolean lazyLoadEnabled() {
+    public boolean isLazyLoadEnabled() {
         return m_lazyLoadEnabled;
     }
 
@@ -316,7 +316,11 @@ public class ArticleModel extends AndroidViewModel implements ApiCommon.ApiCalle
     }
 
     public boolean isLoading() {
-        return m_loadingInProgress;
+        return m_isLoading.getValue();
+    }
+
+    public LiveData<Boolean> getIsLoading() {
+        return m_isLoading;
     }
 
     public LiveData<Integer> getLoadingProgress() {
diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/FeedsFragment.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/FeedsFragment.java
index 513eaeb7..6fe2144a 100755
--- a/org.fox.ttrss/src/main/java/org/fox/ttrss/FeedsFragment.java
+++ b/org.fox.ttrss/src/main/java/org/fox/ttrss/FeedsFragment.java
@@ -21,6 +21,7 @@ import android.widget.TextView;
 
 import androidx.annotation.NonNull;
 import androidx.fragment.app.Fragment;
+import androidx.lifecycle.ViewModelProvider;
 import androidx.loader.app.LoaderManager;
 import androidx.loader.content.Loader;
 import androidx.preference.PreferenceManager;
@@ -51,8 +52,7 @@ import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
-public class FeedsFragment extends Fragment implements OnSharedPreferenceChangeListener,
-		LoaderManager.LoaderCallbacks<JsonElement> {
+public class FeedsFragment extends Fragment implements OnSharedPreferenceChangeListener {
 	private final String TAG = this.getClass().getSimpleName();
 	protected SharedPreferences m_prefs;
 	protected MasterActivity m_activity;
@@ -71,88 +71,6 @@ public class FeedsFragment extends Fragment implements OnSharedPreferenceChangeL
 		m_enableParentBtn = enableParentBtn;
 	}
 
-	@NonNull
-	@Override
-	public Loader<JsonElement> onCreateLoader(int id, Bundle args) {
-
-		if (m_swipeLayout != null)
-			m_swipeLayout.setRefreshing(true);
-
-		HashMap<String,String> params = new HashMap<>();
-		params.put("op", "getFeeds");
-		params.put("sid", m_activity.getSessionId());
-		params.put("include_nested", "true");
-		params.put("cat_id", String.valueOf(m_rootFeed.id));
-
-		return new ApiLoader(getContext(), params);
-	}
-
-	@Override
-	public void onLoadFinished(@NonNull Loader<JsonElement> loader, JsonElement result) {
-		if (m_swipeLayout != null) m_swipeLayout.setRefreshing(false);
-
-		if (result != null) {
-			try {
-				JsonArray content = result.getAsJsonArray();
-				if (content != null) {
-
-					Type listType = new TypeToken<List<Feed>>() {}.getType();
-					List<Feed> feedsJson = new Gson().fromJson(content, listType);
-					List<Feed> feeds = new ArrayList<>();
-
-					if (m_activity.getUnreadOnly() && m_rootFeed.id != Feed.CAT_SPECIAL)
-						feedsJson = feedsJson.stream()
-								.filter(f -> f.unread > 0)
-								.collect(Collectors.toList());
-
-					sortFeeds(feedsJson, m_rootFeed);
-
-					if (m_enableParentBtn) {
-						feeds.add(0, new Feed(Feed.TYPE_GOBACK));
-
-						if (m_rootFeed.id >= 0 && !feedsJson.isEmpty()) {
-							Feed feed = new Feed(m_rootFeed.id, m_rootFeed.title, true);
-
-							feed.unread = feedsJson.stream().map(a -> a.unread).reduce(0, Integer::sum);
-							feed.always_open_headlines = true;
-
-							feeds.add(1, feed);
-						}
-					}
-
-					feeds.addAll(feedsJson);
-
-					feeds.add(new Feed(Feed.TYPE_DIVIDER));
-					feeds.add(new Feed(Feed.TYPE_TOGGLE_UNREAD, getString(R.string.unread_only), true));
-
-					m_adapter.submitList(feeds);
-
-					return;
-				}
-
-			} catch (Exception e) {
-				m_activity.toast(e.getMessage());
-			}
-		}
-
-		ApiLoader apiLoader = (ApiLoader) loader;
-
-		if (apiLoader.getLastError() != null && apiLoader.getLastError() != ApiCommon.ApiError.SUCCESS) {
-			if (apiLoader.getLastError() == ApiCommon.ApiError.LOGIN_FAILED) {
-				m_activity.login(true);
-			} else {
-				if (apiLoader.getLastErrorMessage() != null) {
-					m_activity.toast(getString(apiLoader.getErrorMessage()) + "\n" + apiLoader.getLastErrorMessage());
-				} else {
-					m_activity.toast(apiLoader.getErrorMessage());
-				}
-			}
-		}
-	}
-
-	@Override
-	public void onLoaderReset(Loader<JsonElement> loader) { }
-
 	@SuppressLint("DefaultLocale")
 	static class FeedUnreadComparator implements Comparator<Feed> {
 
@@ -165,7 +83,6 @@ public class FeedsFragment extends Fragment implements OnSharedPreferenceChangeL
 			}
 
 	}
-	
 
 	@SuppressLint("DefaultLocale")
 	static class FeedTitleComparator implements Comparator<Feed> {
@@ -230,39 +147,48 @@ public class FeedsFragment extends Fragment implements OnSharedPreferenceChangeL
 		AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) item
 				.getMenuInfo();
 
-		final Feed feed = m_adapter.getCurrentList().get(info.position);
-
-		Log.d(TAG, "context for feed=" + feed.id);
-
-		int itemId = item.getItemId();
-		if (itemId == R.id.browse_headlines) {
-			Feed tmpFeed = new Feed(feed);
+		// all onContextItemSelected are invoked in sequence so we might get a context menu for headlines, etc
+		// TODO context menu ids defined here should be unique to feedsfragment
+		try {
+			if (info != null) {
+				final Feed feed = m_adapter.getCurrentList().get(info.position);
 
-			if (!neverOpenHeadlines(feed))
-				tmpFeed.always_open_headlines = true;
+				Log.d(TAG, "context for feed=" + feed.id);
 
-			m_activity.onFeedSelected(tmpFeed);
-			return true;
-		} else if (itemId == R.id.browse_feeds) {
-			m_activity.onFeedSelected(feed);
-			return true;
-		} else if (itemId == R.id.unsubscribe_feed) {
-			MaterialAlertDialogBuilder builder = new MaterialAlertDialogBuilder(getContext())
-					.setMessage(getString(R.string.unsubscribe_from_prompt, feed.title))
-					.setPositiveButton(R.string.unsubscribe,
-							(dialog, which) -> m_activity.unsubscribeFeed(feed))
-					.setNegativeButton(R.string.dialog_cancel,
-							(dialog, which) -> {
+				int itemId = item.getItemId();
+				if (itemId == R.id.browse_headlines) {
+					Feed tmpFeed = new Feed(feed);
 
-							});
+					if (!neverOpenHeadlines(feed))
+						tmpFeed.always_open_headlines = true;
 
-			Dialog dlg = builder.create();
-			dlg.show();
+					m_activity.onFeedSelected(tmpFeed);
+					return true;
+				} else if (itemId == R.id.browse_feeds) {
+					m_activity.onFeedSelected(feed);
+					return true;
+				} else if (itemId == R.id.unsubscribe_feed) {
+					MaterialAlertDialogBuilder builder = new MaterialAlertDialogBuilder(getContext())
+							.setMessage(getString(R.string.unsubscribe_from_prompt, feed.title))
+							.setPositiveButton(R.string.unsubscribe,
+									(dialog, which) -> m_activity.unsubscribeFeed(feed))
+							.setNegativeButton(R.string.dialog_cancel,
+									(dialog, which) -> {
+
+									});
+
+					Dialog dlg = builder.create();
+					dlg.show();
+
+					return true;
+				} else if (itemId == R.id.catchup_feed) {
+					m_activity.catchupDialog(feed);
+					return true;
+				}
+			}
 
-			return true;
-		} else if (itemId == R.id.catchup_feed) {
-			m_activity.catchupDialog(feed);
-			return true;
+		} catch (IndexOutOfBoundsException e) {
+			e.printStackTrace();
 		}
 
 		Log.d(TAG, "onContextItemSelected, unhandled id=" + item.getItemId());
@@ -360,9 +286,73 @@ public class FeedsFragment extends Fragment implements OnSharedPreferenceChangeL
 			});
 		}
 
+		FeedsModel model = new ViewModelProvider(this).get(FeedsModel.class);
+
+		model.getUpdatesData().observe(getActivity(), lastUpdate -> {
+			Log.d(TAG, "observed update=" + lastUpdate);
+		});
+
+		model.getIsLoading().observe(getActivity(), isLoading -> {
+			Log.d(TAG, "observed isLoading=" + isLoading);
+
+			if (isAdded() && m_swipeLayout != null)
+				m_swipeLayout.setRefreshing(isLoading);
+		});
+
+		model.getFeeds().observe(getActivity(), feeds -> {
+			Log.d(TAG, "observed feeds=" + feeds);
+
+			if (isAdded()) {
+				onFeedsLoaded(feeds);
+
+				if (model.getLastError() != null && model.getLastError() != ApiCommon.ApiError.SUCCESS) {
+					if (model.getLastError() == ApiCommon.ApiError.LOGIN_FAILED) {
+						m_activity.login(true);
+					} else {
+						if (model.getLastErrorMessage() != null) {
+							m_activity.toast(getString(model.getErrorMessage()) + "\n" + model.getLastErrorMessage());
+						} else {
+							m_activity.toast(model.getErrorMessage());
+						}
+					}
+				}
+			}
+		});
+
 		return view;    	
 	}
 
+	protected void onFeedsLoaded(List<Feed> loadedFeeds) {
+		List<Feed> feedsWork = new ArrayList<>();
+
+		if (m_activity.getUnreadOnly() && m_rootFeed.id != Feed.CAT_SPECIAL)
+			loadedFeeds = loadedFeeds.stream()
+					.filter(f -> f.unread > 0)
+					.collect(Collectors.toList());
+
+		sortFeeds(loadedFeeds, m_rootFeed);
+
+		if (m_enableParentBtn) {
+			feedsWork.add(0, new Feed(Feed.TYPE_GOBACK));
+
+			if (m_rootFeed.id >= 0 && !loadedFeeds.isEmpty()) {
+				Feed feed = new Feed(m_rootFeed.id, m_rootFeed.title, true);
+
+				feed.unread = loadedFeeds.stream().map(a -> a.unread).reduce(0, Integer::sum);
+				feed.always_open_headlines = true;
+
+				feedsWork.add(1, feed);
+			}
+		}
+
+		feedsWork.addAll(loadedFeeds);
+
+		feedsWork.add(new Feed(Feed.TYPE_DIVIDER));
+		feedsWork.add(new Feed(Feed.TYPE_TOGGLE_UNREAD, getString(R.string.unread_only), true));
+
+		m_adapter.submitList(feedsWork);
+	}
+
 	@Override
 	public void onDestroy() {
 		super.onDestroy();
@@ -395,11 +385,8 @@ public class FeedsFragment extends Fragment implements OnSharedPreferenceChangeL
 		if (!isAdded())
 			return;
 
-		if (m_swipeLayout != null) {
-            m_swipeLayout.setRefreshing(true);
-        }
-
-		LoaderManager.getInstance(this).restartLoader(Application.LOADER_FEEDS, null, this).forceLoad();
+		FeedsModel model = new ViewModelProvider(this).get(FeedsModel.class);
+		model.startLoading(m_rootFeed, false);
 	}
 
 	private class FeedViewHolder extends RecyclerView.ViewHolder {
diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/FeedsModel.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/FeedsModel.java
new file mode 100644
index 00000000..bd6ca21f
--- /dev/null
+++ b/org.fox.ttrss/src/main/java/org/fox/ttrss/FeedsModel.java
@@ -0,0 +1,160 @@
+package org.fox.ttrss;
+
+import android.app.Application;
+import android.os.Handler;
+import android.os.Looper;
+import android.util.Log;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.AndroidViewModel;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.reflect.TypeToken;
+
+import org.fox.ttrss.types.ArticleList;
+import org.fox.ttrss.types.Feed;
+
+import java.lang.reflect.Type;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class FeedsModel extends AndroidViewModel implements ApiCommon.ApiCaller {
+    private final String TAG = this.getClass().getSimpleName();
+    private MutableLiveData<List<Feed>> m_feeds = new MutableLiveData<>(new ArrayList<>());
+    private MutableLiveData<Integer> m_loadingProgress = new MutableLiveData<>(Integer.valueOf(0));
+    private MutableLiveData<Long> m_lastUpdate = new MutableLiveData<>(Long.valueOf(0));
+    private MutableLiveData<Boolean> m_isLoading = new MutableLiveData<>(Boolean.valueOf(false));
+
+    private Feed m_feed;
+
+    private ExecutorService m_executor;
+    private Handler m_mainHandler = new Handler(Looper.getMainLooper());
+
+    private final int m_responseCode = 0;
+    protected String m_responseMessage;
+    private int m_apiStatusCode = 0;
+    private String m_lastErrorMessage;
+    private ApiCommon.ApiError m_lastError;
+    private boolean m_rootMode;
+
+    public FeedsModel(@NonNull Application application) {
+        super(application);
+
+        // do we need concurrency or not?
+        m_executor = Executors.newSingleThreadExecutor();
+
+        Log.d(TAG, this + " created");
+    }
+
+    @Override
+    public void setStatusCode(int statusCode) {
+        m_apiStatusCode = statusCode;
+    }
+
+    @Override
+    public void setLastError(ApiCommon.ApiError lastError) {
+        m_lastError = lastError;
+    }
+
+    @Override
+    public void setLastErrorMessage(String message) {
+        m_lastErrorMessage = message;
+    }
+
+    public void startLoading(Feed feed, boolean rootMode) {
+        Log.d(TAG, "startLoading feed id=" + feed.id + " cat=" + feed.is_cat);
+
+        m_feed = feed;
+        m_rootMode = rootMode;
+
+        loadInBackground();
+    }
+
+    @Override
+    public void notifyProgress(int progress) {
+        m_loadingProgress.postValue(progress);
+    }
+
+    protected HashMap<String,String> constructParams() {
+        HashMap<String,String> params = new HashMap<>();
+
+        if (m_rootMode) {
+            params.put("op", "getCategories");
+
+            // this confusingly named option means "return top level categories only"
+            params.put("enable_nested", "true");
+        } else {
+            params.put("op", "getFeeds");
+            params.put("cat_id", String.valueOf(m_feed.id));
+            params.put("include_nested", "true");
+        }
+
+        params.put("sid", ((org.fox.ttrss.Application)getApplication()).getSessionId());
+
+        return params;
+    }
+
+    private void loadInBackground() {
+        Log.d(TAG, this + " loadInBackground");
+
+        m_isLoading.postValue(true);
+
+        HashMap<String,String> params = constructParams();
+
+        m_executor.execute(() -> {
+            JsonElement result = ApiCommon.performRequest(getApplication(), params, this);
+
+            Log.d(TAG, "got result=" + result);
+
+            try {
+                JsonArray content = result.getAsJsonArray();
+                if (content != null) {
+
+                    Type listType = new TypeToken<List<Feed>>() {
+                    }.getType();
+                    List<Feed> feeds = new Gson().fromJson(content, listType);
+
+                    m_feeds.postValue(feeds);
+                }
+            } catch (Exception e) {
+                e.printStackTrace();
+            }
+
+            m_isLoading.postValue(false);
+        });
+    }
+
+    public LiveData<Integer> getLoadingProgress() {
+        return m_loadingProgress;
+    }
+
+    public LiveData<Long> getUpdatesData() {
+        return m_lastUpdate;
+    }
+
+    public LiveData<Boolean> getIsLoading() { return m_isLoading; }
+
+    public LiveData<List<Feed>> getFeeds() {
+        return m_feeds;
+    }
+
+    public int getErrorMessage() {
+        return ApiCommon.getErrorMessage(m_lastError);
+    }
+
+    ApiCommon.ApiError getLastError() {
+        return m_lastError;
+    }
+
+    String getLastErrorMessage() {
+        return m_lastErrorMessage;
+    }
+
+}
\ No newline at end of file
diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/HeadlinesFragment.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/HeadlinesFragment.java
index 099afc60..dba0ac47 100755
--- a/org.fox.ttrss/src/main/java/org/fox/ttrss/HeadlinesFragment.java
+++ b/org.fox.ttrss/src/main/java/org/fox/ttrss/HeadlinesFragment.java
@@ -217,12 +217,12 @@ public class HeadlinesFragment extends androidx.fragment.app.Fragment {
         }
 	}
 
+	// all onContextItemSelected are invoked in sequence so we might get a context menu for headlines, etc
 	public boolean onContextItemSelected(MenuItem item) {
 		AdapterContextMenuInfo info = (AdapterContextMenuInfo) item
 				.getMenuInfo();
 
 		if (info != null) {
-
 			try {
 				Article article = Application.getArticles().get(info.position);
 
@@ -233,6 +233,7 @@ public class HeadlinesFragment extends androidx.fragment.app.Fragment {
 			}
 		}
 
+		Log.d(TAG, "onContextItemSelected, unhandled id=" + item.getItemId());
 		return super.onContextItemSelected(item);
 	}
 
@@ -459,7 +460,7 @@ public class HeadlinesFragment extends androidx.fragment.app.Fragment {
 
 				ArticleModel model = Application.getArticlesModel();
 
-				if (dy > 0 && !m_isLazyLoading && !model.isLoading() && model.lazyLoadEnabled() &&
+				if (dy > 0 && !m_isLazyLoading && !model.isLoading() && model.isLazyLoadEnabled() &&
 						lastVisibleItem >= Application.getArticles().size() - 5) {
 
 					Log.d(TAG, "attempting to lazy load more articles...");
diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/MasterActivity.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/MasterActivity.java
index 643f859c..bdbac8ff 100755
--- a/org.fox.ttrss/src/main/java/org/fox/ttrss/MasterActivity.java
+++ b/org.fox.ttrss/src/main/java/org/fox/ttrss/MasterActivity.java
@@ -165,6 +165,10 @@ public class MasterActivity extends OnlineActivity implements HeadlinesEventList
 			fc.initialize(new Feed(-1, getString(R.string.cat_special), true), false);
 			ft.replace(R.id.feeds_fragment, fc, FRAG_FEEDS);
 
+			/* FeedsFragment ff = new FeedsFragment();
+			ff.initialize(new Feed(12, "Technology", true), true);
+			ft.replace(R.id.feeds_fragment, ff, FRAG_FEEDS); */
+
 			// allow overriding feed to open on startup in non-shortcut mode, default to
 			// open_on_startup prefs setting and not-category
 
diff --git a/org.fox.ttrss/src/main/java/org/fox/ttrss/RootCategoriesFragment.java b/org.fox.ttrss/src/main/java/org/fox/ttrss/RootCategoriesFragment.java
index b61a2736..55c23226 100755
--- a/org.fox.ttrss/src/main/java/org/fox/ttrss/RootCategoriesFragment.java
+++ b/org.fox.ttrss/src/main/java/org/fox/ttrss/RootCategoriesFragment.java
@@ -4,6 +4,7 @@ import android.annotation.SuppressLint;
 import android.os.Bundle;
 
 import androidx.annotation.NonNull;
+import androidx.lifecycle.ViewModelProvider;
 import androidx.loader.content.Loader;
 
 import com.google.gson.Gson;
@@ -23,19 +24,6 @@ import java.util.stream.Collectors;
 public class RootCategoriesFragment extends FeedsFragment {
 	private final String TAG = this.getClass().getSimpleName();
 
-	@Override
-	@NonNull
-	public Loader<JsonElement> onCreateLoader(int id, Bundle args) {
-		HashMap<String, String> params = new HashMap<>();
-		params.put("op", "getCategories");
-		params.put("sid", m_activity.getSessionId());
-
-		// this confusingly named option means "return top level categories only"
-		params.put("enable_nested", "true");
-
-		return new ApiLoader(getContext(), params);
-	}
-
 	@SuppressLint("DefaultLocale")
 	static class CatOrderComparator implements Comparator<Feed> {
 
@@ -74,65 +62,43 @@ public class RootCategoriesFragment extends FeedsFragment {
 	}
 
 	@Override
-	public void onLoadFinished(@NonNull Loader<JsonElement> loader, JsonElement result) {
-		if (m_swipeLayout != null) m_swipeLayout.setRefreshing(false);
-
-		if (result != null) {
-			try {
-				JsonArray content = result.getAsJsonArray();
-				if (content != null) {
-
-					Type listType = new TypeToken<List<Feed>>() {}.getType();
-					List<Feed> feedsJson = new Gson().fromJson(content, listType);
+	public void refresh() {
+		if (!isAdded())
+			return;
 
-					List<Feed> feeds = new ArrayList<>();
-
-					sortFeeds(feedsJson, m_rootFeed);
+		FeedsModel model = new ViewModelProvider(this).get(FeedsModel.class);
+		model.startLoading(m_rootFeed, true);
+	}
 
-					// virtual cats implemented in getCategories since api level 1
-					if (m_activity.getApiLevel() == 0) {
-						feeds.add(0, new Feed(-2, getString(R.string.cat_labels), true));
-						feeds.add(1, new Feed(-1, getString(R.string.cat_special), true));
-						feeds.add(new Feed(0, getString(R.string.cat_uncategorized), true));
-					}
+	@Override
+	protected void onFeedsLoaded(List<Feed> loadedFeeds) {
+		List<Feed> feedsWork = new ArrayList<>();
 
-					if (m_activity.getUnreadOnly())
-						feedsJson = feedsJson.stream()
-								.filter(f -> f.id == Feed.CAT_SPECIAL || f.unread > 0)
-								.collect(Collectors.toList());
+		sortFeeds(loadedFeeds, m_rootFeed);
 
-					feedsJson = feedsJson.stream()
-							.peek(f -> f.is_cat = true)
-							.collect(Collectors.toList());
+		// virtual cats implemented in getCategories since api level 1
+		if (m_activity.getApiLevel() == 0) {
+			feedsWork.add(0, new Feed(-2, getString(R.string.cat_labels), true));
+			feedsWork.add(1, new Feed(-1, getString(R.string.cat_special), true));
+			feedsWork.add(new Feed(0, getString(R.string.cat_uncategorized), true));
+		}
 
-					feeds.addAll(feedsJson);
+		if (m_activity.getUnreadOnly())
+			loadedFeeds = loadedFeeds.stream()
+					.filter(f -> f.id == Feed.CAT_SPECIAL || f.unread > 0)
+					.collect(Collectors.toList());
 
-					feeds.add(new Feed(Feed.TYPE_DIVIDER));
-					feeds.add(new Feed(Feed.TYPE_TOGGLE_UNREAD, getString(R.string.unread_only), true));
+		loadedFeeds = loadedFeeds.stream()
+				.peek(f -> f.is_cat = true)
+				.collect(Collectors.toList());
 
-					m_adapter.submitList(feeds);
+		feedsWork.addAll(loadedFeeds);
 
-					return;
-				}
+		feedsWork.add(new Feed(Feed.TYPE_DIVIDER));
+		feedsWork.add(new Feed(Feed.TYPE_TOGGLE_UNREAD, getString(R.string.unread_only), true));
 
-			} catch (Exception e) {
-				m_activity.toast(e.getMessage());
-			}
-		}
+		m_adapter.submitList(feedsWork);
 
-		ApiLoader apiLoader = (ApiLoader) loader;
-
-		if (apiLoader.getLastError() != null && apiLoader.getLastError() != ApiCommon.ApiError.SUCCESS) {
-			if (apiLoader.getLastError() == ApiCommon.ApiError.LOGIN_FAILED) {
-				m_activity.login(true);
-			} else {
-				if (apiLoader.getLastErrorMessage() != null) {
-					m_activity.toast(getString(apiLoader.getErrorMessage()) + "\n" + apiLoader.getLastErrorMessage());
-				} else {
-					m_activity.toast(apiLoader.getErrorMessage());
-				}
-			}
-		}
 	}
 }