add logic for mustBeValidToInvokeNavigation

mvojtkovszky · Jan 4, 2021 · fee0ea6 · fee0ea6
1 parent c8a5659
commit fee0ea6
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Showing 3 changed files with 52 additions and 10 deletions.
diff --git a/README.md b/README.md
@@ -45,6 +45,7 @@ getCurrentFragment()?.let {
 <br/>Let the fragment define behavioural patterns of it's own by overriding open properties:
 ``` kotlin
 open val isModal: Boolean
+open val mustBeValidToInvokeNavigation: Boolean
 open val overridesBackPress: Boolean
 open val animationEnter: Int
 open val animationExit: Int

diff --git a/app/src/main/kotlin/com/vojtkovszky/singleactivitynavigationexample/MainFragment.kt b/app/src/main/kotlin/com/vojtkovszky/singleactivitynavigationexample/MainFragment.kt
@@ -13,7 +13,10 @@ class MainFragment : BaseSingleFragment() {
     private var _binding: FragmentMainBinding? = null
     private val binding get() = _binding!!
 
-    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+    override val mustBeValidToInvokeNavigation: Boolean
+        get() = true
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
         _binding = FragmentMainBinding.inflate(inflater, container, false)
         return binding.root
     }

diff --git a/...navigation/src/main/kotlin/com/vojtkovszky/singleactivitynavigation/BaseSingleFragment.kt b/...navigation/src/main/kotlin/com/vojtkovszky/singleactivitynavigation/BaseSingleFragment.kt
@@ -34,6 +34,15 @@ abstract class BaseSingleFragment: Fragment() {
     open val isModal: Boolean
         get() = fragmentType == FragmentType.MODAL
 
+    /**
+     * If set to true, any navigation call from this fragment will check for fragment validity
+     * first; meaning fragment has to be added, its activity not null, not destroyed, not finishing.
+     * This ensures navigation methods are never invoked outside of fragment lifecycle.
+     * false is default.
+     */
+    open val mustBeValidToInvokeNavigation: Boolean
+        get() = false
+
     /**
      * If set to true, [BaseSingleActivity]'s onBackPressed method will be prevented from invoking.
      */
@@ -82,65 +91,83 @@ abstract class BaseSingleFragment: Fragment() {
      * Shortcut to [BaseSingleActivity.navigateBackTo]
      */
     fun navigateBackTo(fragmentName: String) {
-        baseSingleActivity?.navigateBackTo(fragmentName)
+        if (canProceedWithNavigation()) {
+            baseSingleActivity?.navigateBackTo(fragmentName)
+        }
     }
 
     /**
      * Shortcut to [BaseSingleActivity.navigateBack]
      */
     fun navigateBack() {
-        baseSingleActivity?.navigateBack()
+        if (canProceedWithNavigation()) {
+            baseSingleActivity?.navigateBack()
+        }
     }
 
     /**
      * Shortcut to [BaseSingleActivity.navigateBackToRoot]
      */
     fun navigateBackToRoot() {
-        baseSingleActivity?.navigateBackToRoot()
+        if (canProceedWithNavigation()) {
+            baseSingleActivity?.navigateBackToRoot()
+        }
     }
 
     /**
      * Shortcut to [BaseSingleActivity.selectRootFragment]
      */
     fun selectRootFragment(positionIndex: Int = 0, popStack: Boolean = true) {
-        baseSingleActivity?.selectRootFragment(positionIndex, popStack)
+        if (canProceedWithNavigation()) {
+            baseSingleActivity?.selectRootFragment(positionIndex, popStack)
+        }
     }
 
     /**
      * Shortcut to [BaseSingleActivity.navigateTo]
      */
     fun navigateTo(fragment: BaseSingleFragment, openAsModal: Boolean = false,
                    ignoreIfAlreadyInStack: Boolean = false) {
-        baseSingleActivity?.navigateTo(fragment, openAsModal, ignoreIfAlreadyInStack)
+        if (canProceedWithNavigation()) {
+            baseSingleActivity?.navigateTo(fragment, openAsModal, ignoreIfAlreadyInStack)
+        }
     }
 
     /**
      * Shortcut to [BaseSingleActivity.openBottomSheet]
      */
     fun openBottomSheet(fragment: BaseSingleFragment) {
-        baseSingleActivity?.openBottomSheet(fragment)
+        if (canProceedWithNavigation()) {
+            baseSingleActivity?.openBottomSheet(fragment)
+        }
     }
 
     /**
      * Shortcut to [BaseSingleActivity.openDialog]
      */
     fun openDialog(fragment: BaseSingleFragment, anchorView: View? = null, useFullWidth: Boolean = true,
                    dialogStyle: Int = DialogFragment.STYLE_NORMAL, dialogTheme: Int = 0) {
-        baseSingleActivity?.openDialog(fragment, anchorView, useFullWidth, dialogStyle, dialogTheme)
+        if (canProceedWithNavigation()) {
+            baseSingleActivity?.openDialog(fragment, anchorView, useFullWidth, dialogStyle, dialogTheme)
+        }
     }
 
     /**
      * Shortcut to [BaseSingleActivity.closeCurrentlyOpenBottomSheet]
      */
     fun closeCurrentlyOpenBottomSheet() {
-        baseSingleActivity?.closeCurrentlyOpenBottomSheet()
+        if (canProceedWithNavigation()) {
+            baseSingleActivity?.closeCurrentlyOpenBottomSheet()
+        }
     }
 
     /**
      * Shortcut to [BaseSingleActivity.closeCurrentlyOpenDialog]
      */
     fun closeCurrentlyOpenDialog() {
-        baseSingleActivity?.closeCurrentlyOpenDialog()
+        if (canProceedWithNavigation()) {
+            baseSingleActivity?.closeCurrentlyOpenDialog()
+        }
     }
     // endregion shortcuts to baseSingleActivity methods
 
@@ -165,6 +192,17 @@ abstract class BaseSingleFragment: Fragment() {
     }
     // endregion add bundle
 
+    // region private methods
+    private fun canProceedWithNavigation(): Boolean {
+        return if (mustBeValidToInvokeNavigation) isValid() else true
+    }
+
+    private fun isValid(): Boolean {
+        return baseSingleActivity != null && !baseSingleActivity!!.isDestroyed &&
+                !baseSingleActivity!!.isFinishing && isAdded
+    }
+    // endregion private methods
+
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         ViewCompat.setTranslationZ(view, translationZ)
         super.onViewCreated(view, savedInstanceState)