Merge pull request #56 from phajduk/added-maptooneordefault

mapToOneOrNull replaced by mapToOneOrDefault

Author: JakeWharton

sqlbrite/src/androidTest/java/com/squareup/sqlbrite/BriteDatabaseTest.java

@@ -145,6 +145,7 @@ public final class BriteDatabaseTest {
         db.createQuery(TABLE_EMPLOYEE, SELECT_EMPLOYEES) //
             .mapToList(new Func1<Cursor, Employee>() {
               private int count;
+
               @Override public Employee call(Cursor cursor) {
                 return count++ == 2 ? null : Employee.MAPPER.call(cursor);
               }
@@ -207,30 +208,38 @@ public final class BriteDatabaseTest {
     }
   }
 
-  @Test public void queryMapToOneOrNull() {
+  @Test public void queryMapToOneOrDefault() {
     Employee employees = db.createQuery(TABLE_EMPLOYEE, SELECT_EMPLOYEES + " LIMIT 1")
-        .mapToOneOrNull(Employee.MAPPER)
+        .mapToOneOrDefault(Employee.MAPPER, null)
         .toBlocking()
         .first();
     assertThat(employees).isEqualTo(new Employee("alice", "Alice Allison"));
   }
 
-  @Test public void queryMapToOneOrNullEmpty() {
+  @Test public void queryMapToOneOrDefaultEmpty() {
     Employee employees = db.createQuery(TABLE_EMPLOYEE, SELECT_EMPLOYEES + " WHERE 1=2")
-        .mapToOneOrNull(Employee.MAPPER)
+        .mapToOneOrDefault(Employee.MAPPER, new Employee("bob", "Bob Bobberson"))
+        .toBlocking()
+        .first();
+    assertThat(employees).isEqualTo(new Employee("bob", "Bob Bobberson"));
+  }
+
+  @Test public void queryMapToOneOrDefaultEmptyUsingNull() {
+    Employee employees = db.createQuery(TABLE_EMPLOYEE, SELECT_EMPLOYEES + " WHERE 1=2")
+        .mapToOneOrDefault(Employee.MAPPER, null)
         .toBlocking()
         .first();
     assertThat(employees).isNull();
   }
 
-  @Test public void queryMapToOneOrNullMapperReturnNullThrows() {
+  @Test public void queryMapToOneOrDefaultMapperReturnNullThrows() {
     BlockingObservable<Employee> employees =
         db.createQuery(TABLE_EMPLOYEE, SELECT_EMPLOYEES) //
-            .mapToOneOrNull(new Func1<Cursor, Employee>() {
+            .mapToOneOrDefault(new Func1<Cursor, Employee>() {
               @Override public Employee call(Cursor cursor) {
                 return null;
               }
-            }) //
+            }, null) //
             .toBlocking();
     try {
       employees.first();
@@ -241,10 +250,10 @@ public final class BriteDatabaseTest {
     }
   }
 
-  @Test public void queryMapToOneOrNullMultipleRowsThrows() {
+  @Test public void queryMapToOneOrDefaultMultipleRowsThrows() {
     BlockingObservable<Employee> employees =
         db.createQuery(TABLE_EMPLOYEE, SELECT_EMPLOYEES + " LIMIT 2") //
-            .mapToOneOrNull(Employee.MAPPER) //
+            .mapToOneOrDefault(Employee.MAPPER, null) //
             .toBlocking();
     try {
       employees.first();

sqlbrite/src/main/java/com/squareup/sqlbrite/QueryObservable.java

@@ -36,7 +36,7 @@ public final class QueryObservable extends Observable<Query> {
    */
   @CheckResult @NonNull
   public final <T> Observable<T> mapToOne(@NonNull final Func1<Cursor, T> mapper) {
-    return lift(new QueryToOneOperator<>(mapper, false));
+    return lift(new QueryToOneOperator<>(mapper, false, null));
   }
 
   /**
@@ -45,18 +45,20 @@ public final <T> Observable<T> mapToOne(@NonNull final Func1<Cursor, T> mapper)
    * <p>
    * It is an error for a query to pass through this operator with more than 1 row in its result
    * set. Use {@code LIMIT 1} on the underlying SQL query to prevent this. Result sets with 0 rows
-   * emit {@code null}.
+   * emit {@code defaultValue}.
    * <p>
    * This method is equivalent to:
    * <pre>{@code
-   * flatMap(q -> q.asRows(mapper).take(1).defaultIfEmpty(null))
+   * flatMap(q -> q.asRows(mapper).take(1).defaultIfEmpty(defaultValue))
    * }</pre>
    *
    * @param mapper Maps the current {@link Cursor} row to {@code T}. May not return null.
+   * @param defaultValue Value returned if result set is empty
    */
   @CheckResult @NonNull
-  public final <T> Observable<T> mapToOneOrNull(@NonNull final Func1<Cursor, T> mapper) {
-    return lift(new QueryToOneOperator<>(mapper, true));
+  public final <T> Observable<T> mapToOneOrDefault(@NonNull final Func1<Cursor, T> mapper,
+      T defaultValue) {
+    return lift(new QueryToOneOperator<>(mapper, true, defaultValue));
   }
 
   /**

sqlbrite/src/main/java/com/squareup/sqlbrite/QueryToOneOperator.java

@@ -9,11 +9,13 @@
 
 final class QueryToOneOperator<T> implements Observable.Operator<T, SqlBrite.Query> {
   private final Func1<Cursor, T> mapper;
-  private final boolean emitNull;
+  private boolean emitDefault;
+  private T defaultValue;
 
-  QueryToOneOperator(Func1<Cursor, T> mapper, boolean emitNull) {
+  QueryToOneOperator(Func1<Cursor, T> mapper, boolean emitDefault, T defaultValue) {
     this.mapper = mapper;
-    this.emitNull = emitNull;
+    this.emitDefault = emitDefault;
+    this.defaultValue = defaultValue;
   }
 
   @Override public Subscriber<? super SqlBrite.Query> call(final Subscriber<? super T> subscriber) {
@@ -35,8 +37,12 @@ final class QueryToOneOperator<T> implements Observable.Operator<T, SqlBrite.Que
           } finally {
             cursor.close();
           }
-          if (!subscriber.isUnsubscribed() && (item != null || emitNull)) {
-            subscriber.onNext(item);
+          if (!subscriber.isUnsubscribed()) {
+            if (item != null) {
+              subscriber.onNext(item);
+            } else if (emitDefault) {
+              subscriber.onNext(defaultValue);
+            }
           }
         } catch (Throwable e) {
           Exceptions.throwIfFatal(e);