Fix #3234

Author: cowtowncoder

release-notes/CREDITS-2.x

@@ -1389,6 +1389,10 @@ Hyeonho Kim (proost@github)
   * Contributed fix for #3227: Content `null` handling not working for root values
    (2.13.0)
 
+Peter Burka (pburka@github)
+  * Reported #3234: StdDeserializer rejects blank (all-whitespace) strings for ints
+   (2.13.0)
+
 Abishek Ravichandran (abrav9595@github)
   * Contributed #3259: Support for BCP 47 `java.util.Locale` serialization/deserialization
    (2.13.0)

release-notes/VERSION-2.x

@@ -66,6 +66,9 @@ Project: jackson-databind
 #3227: Content `null` handling not working for root values
  (reported by João G)
  (fix contributed by proost@github)
+#3234: StdDeserializer rejects blank (all-whitespace) strings for ints
+ (reported by Peter B)
+ (fix proposed by qthegreat3@github)
 #3235: `USE_BASE_TYPE_AS_DEFAULT_IMPL` not working with `DefaultTypeResolverBuilder`
  (reported, fix contributed by silas.u / sialais@github)
 #3238: Add PropertyNamingStrategies.UpperSnakeCaseStrategy (and UPPER_SNAKE_CASE constant)

src/main/java/com/fasterxml/jackson/databind/cfg/CoercionConfig.java

@@ -21,8 +21,10 @@ public class CoercionConfig
     protected final CoercionAction[] _coercionsByShape;
 
     public CoercionConfig() {
-        _coercionsByShape = new CoercionAction[INPUT_SHAPE_COUNT];   
-        _acceptBlankAsEmpty = false;
+        _coercionsByShape = new CoercionAction[INPUT_SHAPE_COUNT];
+        // 23-Sep-2021, tatu: In 2.12 was `false` but should really be `null`
+        //    to mean "not specified" (use defaults)
+        _acceptBlankAsEmpty = null;
     }
 
     protected CoercionConfig(CoercionConfig src) {

src/main/java/com/fasterxml/jackson/databind/cfg/CoercionConfigs.java

@@ -215,10 +215,7 @@ public CoercionAction findCoercion(DeserializationConfig config,
 
         // classic scalars are numbers, booleans; but date/time also considered
         // scalar for this particular purpose
-        final boolean baseScalar = (targetType == LogicalType.Float)
-                || (targetType == LogicalType.Integer)
-                || (targetType == LogicalType.Boolean)
-                || (targetType == LogicalType.DateTime);
+        final boolean baseScalar = _isScalarType(targetType);
 
         if (baseScalar) {
             // Default for setting in 2.x is true
@@ -302,16 +299,33 @@ public CoercionAction findCoercionFromBlankString(DeserializationConfig config,
         }
 
         // First: if using blank as empty is no-go, return what caller specified
-        if (!Boolean.TRUE.equals(acceptBlankAsEmpty)) {
+        if (Boolean.FALSE.equals(acceptBlankAsEmpty)) {
             return actionIfBlankNotAllowed;
         }
-
         // Otherwise, if action found, return that
         if (action != null) {
             return action;
         }
+
+        // 23-Sep-2021, tatu: [databind#3234] Should default to "allow" for Scalar types
+        //    for backwards compatibility
+        if (_isScalarType(targetType)) {
+            return CoercionAction.AsNull;
+        }
+
         // If not, one specific legacy setting to consider...
-        return config.isEnabled(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT) ?
-                    CoercionAction.AsNull : CoercionAction.Fail;
+        if (config.isEnabled(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT)) {
+            return CoercionAction.AsNull;
+        }
+
+        // But finally consider ultimate default to be "false" and so:
+        return actionIfBlankNotAllowed;
+    }
+
+    protected boolean _isScalarType(LogicalType targetType) {
+        return (targetType == LogicalType.Float)
+                || (targetType == LogicalType.Integer)
+                || (targetType == LogicalType.Boolean)
+                || (targetType == LogicalType.DateTime);
     }
 }

src/test/java/com/fasterxml/jackson/failing/CoerceEmptyToInt3234Test.java renamed to src/test/java/com/fasterxml/jackson/databind/convert/CoerceEmptyToInt3234Test.java

@@ -1,4 +1,4 @@
-package com.fasterxml.jackson.failing;
+package com.fasterxml.jackson.databind.convert;
 
 import com.fasterxml.jackson.databind.*;
 
@@ -13,9 +13,14 @@ static class BasicLongWrapper {
         public long value = 7L;
     }
 
+    static class BasicDoubleWrapper {
+        public double value = -1.25;
+    }
+
     private final ObjectMapper MAPPER = newJsonMapper();
     private final ObjectReader READER_INT_BASIC = MAPPER.readerFor(BasicIntWrapper.class);
     private final ObjectReader READER_LONG_BASIC = MAPPER.readerFor(BasicLongWrapper.class);
+    private final ObjectReader READER_DOUBLE_BASIC = MAPPER.readerFor(BasicDoubleWrapper.class);
 
     // // // Ints
 
@@ -44,4 +49,18 @@ public void testSimpleLongFromBlank() throws Exception
         BasicLongWrapper w = READER_LONG_BASIC.readValue(a2q("{'value':' '}"));
         assertEquals(0L, w.value);
     }
+
+    // // // Double
+
+    public void testSimpleDoublegFromEmpty() throws Exception
+    {
+        BasicDoubleWrapper w = READER_DOUBLE_BASIC.readValue(a2q("{'value':''}"));
+        assertEquals((double) 0, w.value);
+    }
+
+    public void testSimpleDoubleFromBlank() throws Exception
+    {
+        BasicDoubleWrapper w = READER_DOUBLE_BASIC.readValue(a2q("{'value':' '}"));
+        assertEquals((double) 0, w.value);
+    }
 }