refactor: make error messages nullable and add default error message

Author: thatfiredev

dataconnect/app/src/main/java/com/google/firebase/example/dataconnect/feature/actordetail/ActorDetailUIState.kt

@@ -7,7 +7,7 @@ import com.google.firebase.dataconnect.movies.GetMovieByIdQuery
 sealed class ActorDetailUIState {
     data object Loading: ActorDetailUIState()
 
-    data class Error(val errorMessage: String): ActorDetailUIState()
+    data class Error(val errorMessage: String?): ActorDetailUIState()
 
     data class Success(
         // Actor is null if it can't be found on the DB

dataconnect/app/src/main/java/com/google/firebase/example/dataconnect/feature/actordetail/ActorDetailViewModel.kt

@@ -57,7 +57,7 @@ class ActorDetailViewModel(
                     )
                 }
             } catch (e: Exception) {
-                _uiState.value = ActorDetailUIState.Error(e.message ?: "")
+                _uiState.value = ActorDetailUIState.Error(e.message)
             }
         }
     }
@@ -76,7 +76,7 @@ class ActorDetailViewModel(
                 // Re-run the query to fetch the actor details
                 fetchActor()
             } catch (e: Exception) {
-                _uiState.value = ActorDetailUIState.Error(e.message ?: "")
+                _uiState.value = ActorDetailUIState.Error(e.message)
             }
         }
     }

dataconnect/app/src/main/java/com/google/firebase/example/dataconnect/feature/genredetail/GenreDetailUIState.kt

@@ -6,7 +6,7 @@ sealed class GenreDetailUIState {
 
     data object Loading: GenreDetailUIState()
 
-    data class Error(val errorMessage: String): GenreDetailUIState()
+    data class Error(val errorMessage: String?): GenreDetailUIState()
 
     data class Success(
         val genreName: String,

dataconnect/app/src/main/java/com/google/firebase/example/dataconnect/feature/genredetail/GenreDetailViewModel.kt

@@ -37,7 +37,7 @@ class GenreDetailViewModel(
                     mostRecent = mostRecent
                 )
             } catch (e: Exception) {
-                _uiState.value = GenreDetailUIState.Error(e.message ?: "")
+                _uiState.value = GenreDetailUIState.Error(e.message)
             }
         }
     }

dataconnect/app/src/main/java/com/google/firebase/example/dataconnect/feature/moviedetail/MovieDetailUIState.kt

@@ -6,7 +6,7 @@ import com.google.firebase.dataconnect.movies.GetMovieByIdQuery
 sealed class MovieDetailUIState {
     data object Loading: MovieDetailUIState()
 
-    data class Error(val errorMessage: String): MovieDetailUIState()
+    data class Error(val errorMessage: String?): MovieDetailUIState()
 
     data class Success(
         // Movie is null if it can't be found on the DB

dataconnect/app/src/main/java/com/google/firebase/example/dataconnect/feature/moviedetail/MovieDetailViewModel.kt

@@ -63,7 +63,7 @@ class MovieDetailViewModel(
                     )
                 }
             } catch (e: Exception) {
-                _uiState.value = MovieDetailUIState.Error(e.message ?: "")
+                _uiState.value = MovieDetailUIState.Error(e.message)
             }
         }
     }
@@ -84,7 +84,7 @@ class MovieDetailViewModel(
                 // Re-run the query to fetch movie
                 fetchMovie()
             } catch (e: Exception) {
-                _uiState.value = MovieDetailUIState.Error(e.message ?: "")
+                _uiState.value = MovieDetailUIState.Error(e.message)
             }
         }
     }
@@ -105,7 +105,7 @@ class MovieDetailViewModel(
                 // Re-run the query to fetch movie
                 fetchMovie()
             } catch (e: Exception) {
-                _uiState.value = MovieDetailUIState.Error(e.message ?: "")
+                _uiState.value = MovieDetailUIState.Error(e.message)
             }
         }
     }
@@ -124,7 +124,7 @@ class MovieDetailViewModel(
                 // Re-run the query to fetch movie
                 fetchMovie()
             } catch (e: Exception) {
-                _uiState.value = MovieDetailUIState.Error(e.message ?: "")
+                _uiState.value = MovieDetailUIState.Error(e.message)
             }
         }
     }

dataconnect/app/src/main/java/com/google/firebase/example/dataconnect/feature/movies/MoviesUIState.kt

@@ -7,7 +7,7 @@ sealed class MoviesUIState {
 
     data object Loading: MoviesUIState()
 
-    data class Error(val errorMessage: String): MoviesUIState()
+    data class Error(val errorMessage: String?): MoviesUIState()
 
     data class Success(
         val top10movies: List<MoviesTop10Query.Data.MoviesItem>,

dataconnect/app/src/main/java/com/google/firebase/example/dataconnect/feature/profile/ProfileUIState.kt

@@ -5,7 +5,7 @@ import com.google.firebase.dataconnect.movies.GetUserByIdQuery
 sealed class ProfileUIState {
     data object Loading: ProfileUIState()
 
-    data class Error(val errorMessage: String): ProfileUIState()
+    data class Error(val errorMessage: String?): ProfileUIState()
 
     data object AuthState: ProfileUIState()
 

dataconnect/app/src/main/java/com/google/firebase/example/dataconnect/feature/profile/ProfileViewModel.kt

@@ -54,7 +54,7 @@ class ProfileViewModel(
                 )?.await()
                 moviesConnector.upsertUser.execute(username = displayName)
             } catch (e: Exception) {
-                _uiState.value = ProfileUIState.Error(e.message ?: "")
+                _uiState.value = ProfileUIState.Error(e.message)
                 e.printStackTrace()
             }
         }
@@ -65,7 +65,7 @@ class ProfileViewModel(
             try {
                 auth.signInWithEmailAndPassword(email, password).await()
             } catch (e: Exception) {
-                _uiState.value = ProfileUIState.Error(e.message ?: "")
+                _uiState.value = ProfileUIState.Error(e.message)
             }
         }
     }
@@ -89,7 +89,7 @@ class ProfileViewModel(
                 )
                 Log.d("DisplayUser", "$user")
             } catch (e: Exception) {
-                _uiState.value = ProfileUIState.Error(e.message ?: "")
+                _uiState.value = ProfileUIState.Error(e.message)
             }
         }
     }

dataconnect/app/src/main/java/com/google/firebase/example/dataconnect/ui/components/ErrorCard.kt

@@ -8,20 +8,22 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
+import com.google.firebase.example.dataconnect.R
 
 @Composable
 fun ErrorCard(
-    errorMessage: String
+    errorMessage: String?
 ) {
     Card(
         colors = CardDefaults.cardColors(containerColor = MaterialTheme.colorScheme.errorContainer),
         modifier = Modifier.padding(16.dp)
             .fillMaxWidth()
     ) {
         Text(
-            text = errorMessage,
+            text = errorMessage ?: stringResource(R.string.unknown_error),
             modifier = Modifier.padding(16.dp)
                 .fillMaxWidth()
         )

dataconnect/app/src/main/res/values/strings.xml

@@ -1,5 +1,6 @@
 <resources>
     <string name="app_name">Firebase Data Connect</string>
+    <string name="unknown_error">An unknown error occurred</string>
 
     <!-- NavBar labels -->
     <string name="label_movies">Movies</string>