Fix #5034: re-write JsonNode.asBoolean(), .asString(), variants

Author: cowtowncoder

release-notes/VERSION

@@ -111,6 +111,8 @@ Versions: 3.x (for earlier see VERSION-2.x)
 #5025: Add support for automatic detection of subtypes (like `@JsonSubTypes`)
   from Java 17 sealed types
  (contributed by Andy B
+#5034: Extend, improve set of `JsonNode.asXxx()` methods for non-number
+  types (Boolean, String)
 - Remove `MappingJsonFactory`
 - Add context parameter for `TypeSerializer` contextualization (`forProperty()`)
 - Default for `JsonNodeFeature.STRIP_TRAILING_BIGDECIMAL_ZEROES` changed to `false` for 3.0

src/main/java/tools/jackson/databind/JsonNode.java

@@ -672,29 +672,31 @@ public String asText(String defaultValue) {
     public abstract Optional<Boolean> booleanValueOpt();
 
     /**
-     * Method that will try to convert value of this node to a Java <b>boolean</b>.
-     * JSON booleans map naturally; integer numbers other than 0 map to true, and
-     * 0 maps to false
+     * Method that will try to convert value of this node to a Java {@code boolean}.
+     * JSON Booleans map naturally; Integer numbers other than 0 map to true, and
+     * 0 maps to false; {@code null} maps to false
      * and Strings 'true' and 'false' map to corresponding values.
-     *<p>
-     * If representation cannot be converted to a boolean value (including structured types
-     * like Objects and Arrays),
-     * default value of <b>false</b> will be returned; no exceptions are thrown.
+     * Other values (including structured types like Objects and Arrays) will
+     * result in a {@link JsonNodeException} being thrown.
+     *
+     * @return Boolean value this node represents, if coercible; exception otherwise
+     *
+     * @throws JsonNodeException if node cannot be coerced to a Java {@code boolean}
      */
     public abstract boolean asBoolean();
 
     /**
-     * Method that will try to convert value of this node to a Java <b>boolean</b>.
-     * JSON booleans map naturally; integer numbers other than 0 map to true, and
-     * 0 maps to false
-     * and Strings 'true' and 'false' map to corresponding values.
-     *<p>
-     * If representation cannot be converted to a boolean value (including structured types
-     * like Objects and Arrays),
-     * specified <b>defaultValue</b> will be returned; no exceptions are thrown.
+     * Similar to {@link #asBoolean()}, but instead of throwing an exception for
+     * non-coercible values, will return specified default value.
      */
     public abstract boolean asBoolean(boolean defaultValue);
 
+    /**
+     * Similar to {@link #asBoolean()}, but instead of throwing an exception for
+     * non-coercible values, will return {@code Optional.empty()}.
+     */
+    public abstract Optional<Boolean> asBooleanOpt();
+
     // // Scalar access: Numbers, generic
 
     /**

src/main/java/tools/jackson/databind/node/BaseJsonNode.java

@@ -32,6 +32,9 @@ public abstract class BaseJsonNode
 {
     private static final long serialVersionUID = 3L;
 
+    protected final static Optional<Boolean> OPT_FALSE = Optional.of(false);
+    protected final static Optional<Boolean> OPT_TRUE = Optional.of(true);
+
     // Simplest way is by using a helper
     Object writeReplace() {
         return NodeSerialization.from(this);
@@ -216,12 +219,29 @@ public Optional<Boolean> booleanValueOpt() {
 
     @Override
     public boolean asBoolean() {
-        return asBoolean(false);
+        Boolean b = _asBoolean();
+        if (b == null) {
+            return _reportCoercionFail("asBoolean()", Boolean.TYPE, "value type not boolean");
+        }
+        return b;
     }
 
     @Override
     public boolean asBoolean(boolean defaultValue) {
-        return defaultValue;
+        Boolean b = _asBoolean();
+        if (b == null) {
+            return defaultValue;
+        }
+        return b;
+    }
+
+    @Override
+    public Optional<Boolean> asBooleanOpt() {
+        Boolean b = _asBoolean();
+        if (b == null) {
+            return Optional.empty();
+        }
+        return b.booleanValue() ? OPT_TRUE : OPT_FALSE;
     }
 
     @Override
@@ -264,7 +284,8 @@ public final JsonNode findPath(String fieldName)
     }
 
     // Also, force (re)definition
-    @Override public abstract int hashCode();
+    @Override
+    public abstract int hashCode();
 
     /*
     /**********************************************************************
@@ -417,6 +438,24 @@ protected ArrayNode _withArray(JsonPointer origPtr,
         return null;
     }
 
+    /*
+    /**********************************************************************
+    /* asXxx() helper methods for sub-classes to implement
+    /**********************************************************************
+     */
+
+    /**
+     * Method sub-classes should override if they can produce {@code boolean}
+     * values via {@link #asBoolean()} -- if not, return {@code null} (in which
+     * case appropriate error will be thrown or default value returned).
+     *
+     * @return Coerced value if possible; otherwise {@code null} to indicate this
+     *     node cannot be coerced.
+     */
+    protected Boolean _asBoolean() {
+        return null;
+    }
+
     /*
     /**********************************************************************
     /* JacksonSerializable

src/main/java/tools/jackson/databind/node/BigIntegerNode.java

@@ -75,6 +75,11 @@ public BigIntegerNode(BigInteger v) {
     /* Overridden JsonNode methods, scalar access
     /**********************************************************************
      */
+
+    @Override
+    protected Boolean _asBoolean() {
+        return !BigInteger.ZERO.equals(_value);
+    }
 
     @Override
     public Number numberValue() {
@@ -185,22 +190,11 @@ public Optional<BigDecimal> decimalValueOpt() {
         return Optional.of(new BigDecimal(_value));
     }
 
-    /*
-    /**********************************************************
-    /* General type coercions
-    /**********************************************************
-     */
-
     @Override
     public String asString() {
         return _value.toString();
     }
 
-    @Override
-    public boolean asBoolean(boolean defaultValue) {
-        return !BigInteger.ZERO.equals(_value);
-    }
-
     /*
     /**********************************************************
     /* Other overrides

src/main/java/tools/jackson/databind/node/BooleanNode.java

@@ -19,9 +19,6 @@ public class BooleanNode
 
     public final static BooleanNode TRUE = new BooleanNode(true);
     public final static BooleanNode FALSE = new BooleanNode(false);
-
-    private final static Optional<Boolean> OPT_FALSE = Optional.of(false);
-    private final static Optional<Boolean> OPT_TRUE = Optional.of(true);
 
     private final boolean _value;
 
@@ -72,31 +69,43 @@ protected String _valueDesc() {
     /**********************************************************************
      */
 
+    // // // Override "asBoolean()" methods as minor optimization
+    
     @Override
-    public boolean booleanValue() {
+    public final boolean asBoolean() {
         return _value;
     }
 
     @Override
-    public boolean booleanValue(boolean defaultValue) {
+    public final boolean asBoolean(boolean defaultValue) {
         return _value;
     }
 
     @Override
-    public Optional<Boolean> booleanValueOpt() {
+    public Optional<Boolean> asBooleanOpt() {
         return _value ? OPT_TRUE : OPT_FALSE;
     }
+    
+    @Override
+    protected Boolean _asBoolean() {
+        return _value;
+    }
 
     @Override
-    public boolean asBoolean() {
+    public boolean booleanValue() {
         return _value;
     }
 
     @Override
-    public boolean asBoolean(boolean defaultValue) {
+    public boolean booleanValue(boolean defaultValue) {
         return _value;
     }
 
+    @Override
+    public Optional<Boolean> booleanValueOpt() {
+        return _value ? OPT_TRUE : OPT_FALSE;
+    }
+
     @Override
     public int asInt(int defaultValue) {
         return _value ? 1 : 0;

src/main/java/tools/jackson/databind/node/IntNode.java

@@ -79,6 +79,11 @@ public static IntNode valueOf(int i) {
     /**********************************************************************
      */
 
+    @Override
+    protected Boolean _asBoolean() {
+        return (_value != 0);
+    }
+    
     @Override
     public Number numberValue() {
         return Integer.valueOf(_value);
@@ -145,11 +150,6 @@ public String asString() {
         return String.valueOf(_value);
     }
 
-    @Override
-    public boolean asBoolean(boolean defaultValue) {
-        return _value != 0;
-    }
-
     /*
     /**********************************************************************
     /* Overridden JsonNode methods, other
@@ -163,6 +163,12 @@ public final void serialize(JsonGenerator g, SerializationContext provider)
         g.writeNumber(_value);
     }
 
+    /*
+    /**********************************************************************
+    /* Overridden standard methods
+    /**********************************************************************
+     */
+    
     @Override
     public boolean equals(Object o)
     {

src/main/java/tools/jackson/databind/node/LongNode.java

@@ -61,7 +61,12 @@ public boolean canConvertToInt() {
     /* Overridden JsonNode methods, scalar access
     /**********************************************************************
      */
-    
+
+    @Override
+    protected Boolean _asBoolean() {
+        return (_value != 0L);
+    }
+
     @Override
     public Number numberValue() {
         return Long.valueOf(_value);
@@ -135,18 +140,19 @@ public String asString() {
         return String.valueOf(_value);
     }
 
-    @Override
-    public boolean asBoolean(boolean defaultValue) {
-        return _value != 0;
-    }
+    /*
+    /**********************************************************************
+    /* Overridden methods, other
+    /**********************************************************************
+     */
 
     @Override
     public final void serialize(JsonGenerator jg, SerializationContext provider)
         throws JacksonException
     {
         jg.writeNumber(_value);
     }
-
+    
     @Override
     public boolean equals(Object o)
     {

src/main/java/tools/jackson/databind/node/NullNode.java

@@ -36,16 +36,27 @@ public JsonNodeType getNodeType() {
     @Override
     public NullNode deepCopy() { return this; }
 
+    /*
+    /**********************************************************************
+    /* Overridden JsonNode methods, scalar access
+    /**********************************************************************
+     */
+
     @Override
-    protected String _valueDesc() {
-        return "<null>";
+    protected Boolean _asBoolean() {
+        return Boolean.FALSE;
     }
 
     @Override
     public String asString(String defaultValue) { return defaultValue; }
 
     @Override public String asString() { return "null"; }
 
+    @Override
+    protected String _valueDesc() {
+        return "<null>";
+    }
+
     @SuppressWarnings("unchecked")
     @Override
     public JsonNode requireNonNull() {