Add databinding support

Base support for binding

Add sample with simple binding

Code cleaning

Cleaning code - removing unnecessary helpers

Add cast exception

Add annotatoins, code cleaning and refactoring

Remove implementation of getViewModelBindingConfig from ViewModelBaseFragment

Author: Stepan Sanda

build.gradle

@@ -3,7 +3,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.2.0'
+        classpath 'com.android.tools.build:gradle:2.2.2'
     }
 }
 

library/build.gradle

@@ -21,6 +21,10 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }
+
+    dataBinding {
+        enabled = true;
+    }
 }
 
 dependencies {

library/src/main/java/eu/inloop/viewmodel/IView.java

@@ -1,5 +1,16 @@
 package eu.inloop.viewmodel;
 
-public interface IView {
+import android.support.annotation.Nullable;
+
+import eu.inloop.viewmodel.binding.ViewModelBindingConfig;
 
+public interface IView {
+    /**
+     * This method is used for Data Binding to bind correct layout and variable atomatically
+     * Can return null value in case that Data Binding is not used.
+     *
+     * @return defined ViewModelBinding Config for a specific screen.
+     */
+    @Nullable
+    ViewModelBindingConfig getViewModelBindingConfig();
 }

library/src/main/java/eu/inloop/viewmodel/ViewModelHelper.java

@@ -2,14 +2,19 @@
 
 import android.app.Activity;
 import android.content.Intent;
+import android.databinding.DataBindingUtil;
+import android.databinding.ViewDataBinding;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.v4.app.Fragment;
 import android.util.Log;
+import android.view.LayoutInflater;
 
 import java.util.UUID;
 
+import eu.inloop.viewmodel.binding.ViewModelBindingConfig;
+
 public class ViewModelHelper<T extends IView, R extends AbstractViewModel<T>> {
 
     @NonNull
@@ -21,18 +26,22 @@ public class ViewModelHelper<T extends IView, R extends AbstractViewModel<T>> {
     @Nullable
     private R mViewModel;
 
+    @Nullable
+    private ViewDataBinding mBinding;
+
     private boolean mModelRemoved;
     private boolean mOnSaveInstanceCalled;
 
     /**
      * Call from {@link android.app.Activity#onCreate(android.os.Bundle)} or
      * {@link android.support.v4.app.Fragment#onCreate(android.os.Bundle)}
-     * @param activity parent activity
+     *
+     * @param activity           parent activity
      * @param savedInstanceState savedInstance state from {@link Activity#onCreate(Bundle)} or
      *                           {@link Fragment#onCreate(Bundle)}
-     * @param viewModelClass the {@link Class} of your ViewModel
-     * @param arguments pass {@link Fragment#getArguments()}  or
-     *                  {@link Activity#getIntent()}.{@link Intent#getExtras() getExtras()}
+     * @param viewModelClass     the {@link Class} of your ViewModel
+     * @param arguments          pass {@link Fragment#getArguments()}  or
+     *                           {@link Activity#getIntent()}.{@link Intent#getExtras() getExtras()}
      */
     public void onCreate(@NonNull Activity activity,
                          @Nullable Bundle savedInstanceState,
@@ -62,7 +71,7 @@ public void onCreate(@NonNull Activity activity,
         if (null == viewModelProvider) {
             throw new IllegalStateException("ViewModelProvider for activity " + activity + " was null."); //NON-NLS
         }
-        
+
         final ViewModelProvider.ViewModelWrapper<T> viewModelWrapper = viewModelProvider.getViewModel(mScreenId, viewModelClass);
         //noinspection unchecked
         mViewModel = (R) viewModelWrapper.viewModel;
@@ -79,6 +88,7 @@ public void onCreate(@NonNull Activity activity,
     /**
      * Call from {@link android.support.v4.app.Fragment#onViewCreated(android.view.View, android.os.Bundle)}
      * or {@link android.app.Activity#onCreate(android.os.Bundle)}
+     *
      * @param view view
      */
     public void setView(@NonNull final T view) {
@@ -89,10 +99,44 @@ public void setView(@NonNull final T view) {
         mViewModel.onBindView(view);
     }
 
+    public void performBinding(@NonNull final IView bindingView) {
+        // skip if already create
+        if (mBinding != null) {
+            return;
+        }
+
+        // get ViewModelBinding config
+        final ViewModelBindingConfig viewModelConfig = bindingView.getViewModelBindingConfig();
+        // if fragment not providing ViewModelBindingConfig, do not perform binding operations
+        if (viewModelConfig == null) {
+            return;
+        }
+
+        // perform Data Binding initialization
+        final ViewDataBinding viewDataBinding;
+        if (bindingView instanceof Activity) {
+            viewDataBinding = DataBindingUtil.setContentView(((Activity) bindingView), viewModelConfig.getLayoutResource());
+        } else if (bindingView instanceof Fragment) {
+            viewDataBinding = DataBindingUtil.inflate(LayoutInflater.from(viewModelConfig.getContext()), viewModelConfig.getLayoutResource(), null, false);
+        } else {
+            throw new IllegalArgumentException("View must be an instance of Activity or Fragment (support-v4).");
+        }
+
+        // bind all together
+        if (!viewDataBinding.setVariable(viewModelConfig.getViewModelVariableName(), getViewModel())) {
+            throw new IllegalArgumentException("Binding variable wasn't set successfully. Probably viewModelVariableName of your " +
+                    "ViewModelBindingConfig of " + bindingView.getClass().getSimpleName() + " doesn't match any variable in "
+                    + viewDataBinding.getClass().getSimpleName());
+        }
+
+        mBinding = viewDataBinding;
+    }
+
     /**
      * Use in case this model is associated with an {@link android.support.v4.app.Fragment}
      * Call from {@link android.support.v4.app.Fragment#onDestroyView()}. Use in case model is associated
      * with Fragment
+     *
      * @param fragment fragment
      */
     public void onDestroyView(@NonNull Fragment fragment) {
@@ -104,11 +148,13 @@ public void onDestroyView(@NonNull Fragment fragment) {
         if (fragment.getActivity() != null && fragment.getActivity().isFinishing()) {
             removeViewModel(fragment.getActivity());
         }
+        mBinding = null;
     }
 
     /**
      * Use in case this model is associated with an {@link android.support.v4.app.Fragment}
      * Call from {@link android.support.v4.app.Fragment#onDestroy()}
+     *
      * @param fragment fragment
      */
     public void onDestroy(@NonNull final Fragment fragment) {
@@ -126,11 +172,13 @@ public void onDestroy(@NonNull final Fragment fragment) {
             }
             removeViewModel(fragment.getActivity());
         }
+        mBinding = null;
     }
 
     /**
      * Use in case this model is associated with an {@link android.app.Activity}
      * Call from {@link android.app.Activity#onDestroy()}
+     *
      * @param activity activity
      */
     public void onDestroy(@NonNull final Activity activity) {
@@ -142,6 +190,7 @@ public void onDestroy(@NonNull final Activity activity) {
         if (activity.isFinishing()) {
             removeViewModel(activity);
         }
+        mBinding = null;
     }
 
     /**
@@ -172,6 +221,7 @@ public void onStart() {
      * Throws an {@link IllegalStateException} in case the ViewModel is null. This can happen
      * if you call this method too soon - before {@link Activity#onCreate(Bundle)} or {@link Fragment#onCreate(Bundle)}
      * or this {@link ViewModelHelper} is not properly setup.
+     *
      * @return {@link R}
      */
     @NonNull
@@ -186,6 +236,7 @@ public R getViewModel() {
      * Call from {@link android.app.Activity#onSaveInstanceState(android.os.Bundle)}
      * or {@link android.support.v4.app.Fragment#onSaveInstanceState(android.os.Bundle)}.
      * This allows the model to save its state.
+     *
      * @param bundle bundle
      */
     public void onSaveInstanceState(@NonNull Bundle bundle) {
@@ -196,6 +247,11 @@ public void onSaveInstanceState(@NonNull Bundle bundle) {
         }
     }
 
+    @Nullable
+    public ViewDataBinding getBinding() {
+        return mBinding;
+    }
+
     private void removeViewModel(@NonNull final Activity activity) {
         if (mViewModel != null && !mModelRemoved) {
             final ViewModelProvider viewModelProvider = getViewModelProvider(activity).getViewModelProvider();
@@ -205,6 +261,7 @@ private void removeViewModel(@NonNull final Activity activity) {
             viewModelProvider.remove(mScreenId);
             mViewModel.onDestroy();
             mModelRemoved = true;
+            mBinding = null;
         }
     }
 

library/src/main/java/eu/inloop/viewmodel/base/ViewModelBaseFragment.java

@@ -20,61 +20,68 @@ public abstract class ViewModelBaseFragment<T extends IView, R extends AbstractV
     @Override
     public void onCreate(@Nullable final Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        mViewModeHelper.onCreate(getActivity(), savedInstanceState, getViewModelClass(), getArguments());
-    }
-
-    @Nullable
-    public abstract Class<R> getViewModelClass();
-
-    /**
-     * Call this after your view is ready - usually on the end of {@link Fragment#onViewCreated(View, Bundle)}
-     * @param view view
-     */
-    protected void setModelView(@NonNull final T view) {
-        mViewModeHelper.setView(view);
+        getViewModeHelper().onCreate(getActivity(), savedInstanceState, getViewModelClass(), getArguments());
     }
 
     @CallSuper
     @Override
     public void onSaveInstanceState(@NonNull final Bundle outState) {
         super.onSaveInstanceState(outState);
-        mViewModeHelper.onSaveInstanceState(outState);
+        getViewModeHelper().onSaveInstanceState(outState);
     }
 
     @CallSuper
     @Override
     public void onStart() {
         super.onStart();
-        mViewModeHelper.onStart();
+        getViewModeHelper().onStart();
     }
 
     @CallSuper
     @Override
     public void onStop() {
         super.onStop();
-        mViewModeHelper.onStop();
+        getViewModeHelper().onStop();
     }
 
     @CallSuper
     @Override
     public void onDestroyView() {
-        mViewModeHelper.onDestroyView(this);
+        getViewModeHelper().onDestroyView(this);
         super.onDestroyView();
     }
 
     @CallSuper
     @Override
     public void onDestroy() {
-        mViewModeHelper.onDestroy(this);
+        getViewModeHelper().onDestroy(this);
         super.onDestroy();
     }
 
+    @Nullable
+    public abstract Class<R> getViewModelClass();
+
     /**
      * @see ViewModelHelper#getViewModel()
      */
     @NonNull
     @SuppressWarnings("unused")
     public R getViewModel() {
-       return mViewModeHelper.getViewModel();
+        return getViewModeHelper().getViewModel();
+    }
+
+    @NonNull
+    public ViewModelHelper<T, R> getViewModeHelper() {
+        return mViewModeHelper;
+    }
+
+    /**
+     * Call this after your view is ready - usually on the end of {@link
+     * Fragment#onViewCreated(View, Bundle)}
+     *
+     * @param view view
+     */
+    protected void setModelView(@NonNull final T view) {
+        getViewModeHelper().setView(view);
     }
 }

library/src/main/java/eu/inloop/viewmodel/binding/ViewModelBaseBindingFragment.java

@@ -0,0 +1,48 @@
+package eu.inloop.viewmodel.binding;
+
+import android.databinding.ViewDataBinding;
+import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import org.jetbrains.annotations.NotNull;
+
+import eu.inloop.viewmodel.AbstractViewModel;
+import eu.inloop.viewmodel.IView;
+import eu.inloop.viewmodel.base.ViewModelBaseFragment;
+
+public abstract class ViewModelBaseBindingFragment<T extends IView, R extends AbstractViewModel<T>, B extends ViewDataBinding>
+        extends ViewModelBaseFragment<T, R>
+        implements IView {
+
+    @Override
+    public void onCreate(@Nullable Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        getViewModeHelper().performBinding(this);
+    }
+
+    @Nullable
+    @Override
+    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
+        getViewModeHelper().performBinding(this);
+        final ViewDataBinding binding = getViewModeHelper().getBinding();
+        if (binding != null) {
+            return binding.getRoot();
+        } else {
+            throw new IllegalStateException("Binding cannot be null. Perform binding before calling getBinding()");
+        }
+    }
+
+    @SuppressWarnings("unused")
+    @NotNull
+    public B getBinding() {
+        try {
+            return (B) getViewModeHelper().getBinding();
+        } catch (ClassCastException ex) {
+            throw new IllegalStateException("Method getViewModelBindingConfig() has to return same " +
+                    "ViewDataBinding type as it is set to base Fragment");
+        }
+    }
+}