Fix #3690: improve error message for to-string coercion (#3717)

Author: cowtowncoder

release-notes/CREDITS-2.x

@@ -1039,6 +1039,8 @@ João Guerra (joca-bt@github)
   (2.11.1)
   * Reported #3227: Content `null` handling not working for root values
   (2.13.0)
+  * Reported #3690: Incorrect target type for arrays when disabling coercion
+  (2.15.0)
 
 Ryan Bohn (bohnman@github)
   * Reported #2475: `StringCollectionSerializer` calls `JsonGenerator.setCurrentValue(value)`,

release-notes/VERSION-2.x

@@ -12,6 +12,8 @@ Project: jackson-databind
 #3680: Timestamp in classes inside jar showing 02/01/1980
  (fix contributed by Hervé B)
 #3682: Transient `Field`s are not ignored as Mutators if there is visible Getter
+#3690: Incorrect target type for arrays when disabling coercion
+ (reported by João G)
 #3708: Seems like `java.nio.file.Path` is safe for Android API level 26
  (contributed by @pjfanning)
 

src/main/java/com/fasterxml/jackson/databind/deser/std/StdDeserializer.java

@@ -1401,6 +1401,9 @@ protected final String _parseString(JsonParser p, DeserializationContext ctxt,
         throws IOException
     {
         CoercionAction act = CoercionAction.TryConvert;
+        // 05-Jan-2022, tatu: We are usually coercing into `String` as element,
+        //    or such; `_valueClass` would be wrong choice here
+        final Class<?> rawTargetType = String.class;
 
         switch (p.currentTokenId()) {
         case JsonTokenId.ID_STRING:
@@ -1420,17 +1423,20 @@ protected final String _parseString(JsonParser p, DeserializationContext ctxt,
         case JsonTokenId.ID_START_OBJECT:
             return ctxt.extractScalarFromObject(p, this, _valueClass);
         case JsonTokenId.ID_NUMBER_INT:
-            act = _checkIntToStringCoercion(p, ctxt, _valueClass);
+            act = _checkIntToStringCoercion(p, ctxt, rawTargetType);
             break;
         case JsonTokenId.ID_NUMBER_FLOAT:
-            act = _checkFloatToStringCoercion(p, ctxt, _valueClass);
+            act = _checkFloatToStringCoercion(p, ctxt, rawTargetType);
             break;
         case JsonTokenId.ID_TRUE:
         case JsonTokenId.ID_FALSE:
-            act = _checkBooleanToStringCoercion(p, ctxt, _valueClass);
+            act = _checkBooleanToStringCoercion(p, ctxt, rawTargetType);
             break;
         }
 
+        // !!! 05-Jan-2022, tatu: This might work in practice, but in theory
+        //   we should not use "nullProvider" of this deserializer as this
+        //   unlikely to be what we want (it's for containing type, not String)
         if (act == CoercionAction.AsNull) {
             return (String) nullProvider.getNullValue(ctxt);
         }
@@ -1655,7 +1661,7 @@ protected CoercionAction _checkCoercionFail(DeserializationContext ctxt,
         if (act == CoercionAction.Fail) {
             ctxt.reportBadCoercion(this, targetType, inputValue,
 "Cannot coerce %s to %s (but could if coercion was enabled using `CoercionConfig`)",
-inputDesc, _coercedTypeDesc());
+inputDesc, _coercedTypeDesc(targetType));
         }
         return act;
     }
@@ -1777,8 +1783,7 @@ protected String _coercedTypeDesc() {
             typeDesc = ClassUtil.getTypeDescription(t);
         } else {
             Class<?> cls = handledType();
-            structured = cls.isArray() || Collection.class.isAssignableFrom(cls)
-                || Map.class.isAssignableFrom(cls);
+            structured = ClassUtil.isCollectionMapOrArray(cls);
             typeDesc = ClassUtil.getClassDescription(cls);
         }
         if (structured) {
@@ -1787,6 +1792,23 @@ protected String _coercedTypeDesc() {
         return typeDesc+" value";
     }
 
+    /**
+     * Helper method called to get a description of type into which a scalar value coercion
+     * is being applied, to be used for constructing exception messages
+     * on coerce failure.
+     *
+     * @return Message with backtick-enclosed name of target type
+     *
+     * @since 2.15
+     */
+    protected String _coercedTypeDesc(Class<?> rawTargetType) {
+        String typeDesc = ClassUtil.getClassDescription(rawTargetType);
+        if (ClassUtil.isCollectionMapOrArray(rawTargetType)) {
+            return "element of "+typeDesc;
+        }
+        return typeDesc+" value";
+    }
+
     /*
     /**********************************************************************
     /* Helper methods for sub-classes, coercions, older (pre-2.12), deprecated

src/test/java/com/fasterxml/jackson/databind/convert/CoerceBoolToStringTest.java

@@ -67,7 +67,7 @@ public void testCoerceConfigToFail() throws JsonProcessingException
     {
         _verifyCoerceFail(MAPPER_TO_FAIL, String.class, "true");
         _verifyCoerceFail(MAPPER_TO_FAIL, StringWrapper.class, "{\"str\": false}", "string");
-        _verifyCoerceFail(MAPPER_TO_FAIL, String[].class, "[ true ]", "element of `java.lang.String[]`");
+        _verifyCoerceFail(MAPPER_TO_FAIL, String[].class, "[ true ]", "to `java.lang.String` value");
     }
 
     /*

src/test/java/com/fasterxml/jackson/databind/convert/CoerceFloatToIntTest.java

@@ -77,26 +77,26 @@ public void testLegacyFailDoubleToInt() throws Exception
         _verifyCoerceFail(READER_LEGACY_FAIL, Integer.class, "1.5", "java.lang.Integer");
         _verifyCoerceFail(READER_LEGACY_FAIL, Integer.TYPE, "1.5", "int");
         _verifyCoerceFail(READER_LEGACY_FAIL, IntWrapper.class, "{\"i\":-2.25 }", "int");
-        _verifyCoerceFail(READER_LEGACY_FAIL, int[].class, "[ 2.5 ]", "element of `int[]`");
+        _verifyCoerceFail(READER_LEGACY_FAIL, int[].class, "[ 2.5 ]", "to `int` value");
     }
 
     public void testLegacyFailDoubleToLong() throws Exception
     {
         _verifyCoerceFail(READER_LEGACY_FAIL, Long.class, "0.5");
         _verifyCoerceFail(READER_LEGACY_FAIL, Long.TYPE, "-2.5");
         _verifyCoerceFail(READER_LEGACY_FAIL, LongWrapper.class, "{\"l\": 7.7 }");
-        _verifyCoerceFail(READER_LEGACY_FAIL, long[].class, "[ -1.35 ]", "element of `long[]`");
+        _verifyCoerceFail(READER_LEGACY_FAIL, long[].class, "[ -1.35 ]", "to `long` value");
     }
 
     public void testLegacyFailDoubleToOther() throws Exception
     {
         _verifyCoerceFail(READER_LEGACY_FAIL, Short.class, "0.5");
         _verifyCoerceFail(READER_LEGACY_FAIL, Short.TYPE, "-2.5");
-        _verifyCoerceFail(READER_LEGACY_FAIL, short[].class, "[ -1.35 ]", "element of `short[]`");
+        _verifyCoerceFail(READER_LEGACY_FAIL, short[].class, "[ -1.35 ]", "to `short` value");
 
         _verifyCoerceFail(READER_LEGACY_FAIL, Byte.class, "0.5");
         _verifyCoerceFail(READER_LEGACY_FAIL, Byte.TYPE, "-2.5");
-        _verifyCoerceFail(READER_LEGACY_FAIL, byte[].class, "[ -1.35 ]", "element of `byte[]`");
+        _verifyCoerceFail(READER_LEGACY_FAIL, byte[].class, "[ -1.35 ]", "to `byte` value");
 
         _verifyCoerceFail(READER_LEGACY_FAIL, BigInteger.class, "25236.256");
 
@@ -280,20 +280,20 @@ public void testCoerceConfigFailFromFloat() throws Exception
         _verifyCoerceFail(MAPPER_TO_FAIL, Integer.class, "1.5");
         _verifyCoerceFail(MAPPER_TO_FAIL, Integer.TYPE, "1.5");
         _verifyCoerceFail(MAPPER_TO_FAIL, IntWrapper.class, "{\"i\":-2.25 }", "int");
-        _verifyCoerceFail(MAPPER_TO_FAIL, int[].class, "[ 2.5 ]", "element of `int[]`");
+        _verifyCoerceFail(MAPPER_TO_FAIL, int[].class, "[ 2.5 ]", "to `int` value");
 
         _verifyCoerceFail(MAPPER_TO_FAIL, Long.class, "0.5");
         _verifyCoerceFail(MAPPER_TO_FAIL, Long.TYPE, "-2.5");
         _verifyCoerceFail(MAPPER_TO_FAIL, LongWrapper.class, "{\"l\": 7.7 }");
-        _verifyCoerceFail(MAPPER_TO_FAIL, long[].class, "[ -1.35 ]", "element of `long[]`");
+        _verifyCoerceFail(MAPPER_TO_FAIL, long[].class, "[ -1.35 ]", "to `long` value");
 
         _verifyCoerceFail(MAPPER_TO_FAIL, Short.class, "0.5");
         _verifyCoerceFail(MAPPER_TO_FAIL, Short.TYPE, "-2.5");
-        _verifyCoerceFail(MAPPER_TO_FAIL, short[].class, "[ -1.35 ]", "element of `short[]`");
+        _verifyCoerceFail(MAPPER_TO_FAIL, short[].class, "[ -1.35 ]", "to `short` value");
 
         _verifyCoerceFail(MAPPER_TO_FAIL, Byte.class, "0.5");
         _verifyCoerceFail(MAPPER_TO_FAIL, Byte.TYPE, "-2.5");
-        _verifyCoerceFail(MAPPER_TO_FAIL, byte[].class, "[ -1.35 ]", "element of `byte[]`");
+        _verifyCoerceFail(MAPPER_TO_FAIL, byte[].class, "[ -1.35 ]", "to `byte` value");
 
         _verifyCoerceFail(MAPPER_TO_FAIL, BigInteger.class, "25236.256");
     }

src/test/java/com/fasterxml/jackson/databind/convert/CoerceFloatToStringTest.java

@@ -68,7 +68,8 @@ public void testCoerceConfigToFail() throws JsonProcessingException
     {
         _verifyCoerceFail(MAPPER_TO_FAIL, String.class, "3.5");
         _verifyCoerceFail(MAPPER_TO_FAIL, StringWrapper.class, "{\"str\": -5.3}", "string");
-        _verifyCoerceFail(MAPPER_TO_FAIL, String[].class, "[ 2.1 ]", "element of `java.lang.String[]`");
+        _verifyCoerceFail(MAPPER_TO_FAIL, String[].class, "[ 2.1 ]",
+                "to `java.lang.String` value");
     }
 
     /*

src/test/java/com/fasterxml/jackson/databind/convert/CoerceIntToFloatTest.java

@@ -110,12 +110,12 @@ public void testCoerceConfigToFail() throws JsonProcessingException
         _verifyCoerceFail(MAPPER_TO_FAIL, Float.class, "3");
         _verifyCoerceFail(MAPPER_TO_FAIL, Float.TYPE, "-2");
         _verifyCoerceFail(MAPPER_TO_FAIL, FloatWrapper.class, "{\"f\": -5}", "float");
-        _verifyCoerceFail(MAPPER_TO_FAIL, float[].class, "[ 2 ]", "element of `float[]`");
+        _verifyCoerceFail(MAPPER_TO_FAIL, float[].class, "[ 2 ]", "to `float` value");
 
         _verifyCoerceFail(MAPPER_TO_FAIL, Double.class, "-1");
         _verifyCoerceFail(MAPPER_TO_FAIL, Double.TYPE, "4");
         _verifyCoerceFail(MAPPER_TO_FAIL, DoubleWrapper.class, "{\"d\": 2}", "double");
-        _verifyCoerceFail(MAPPER_TO_FAIL, double[].class, "[ -2 ]", "element of `double[]`");
+        _verifyCoerceFail(MAPPER_TO_FAIL, double[].class, "[ -2 ]", "to `double` value");
 
         _verifyCoerceFail(MAPPER_TO_FAIL, BigDecimal.class, "73455342");
     }

src/test/java/com/fasterxml/jackson/databind/convert/CoerceIntToStringTest.java

@@ -68,7 +68,7 @@ public void testCoerceConfigToFail() throws JsonProcessingException
     {
         _verifyCoerceFail(MAPPER_TO_FAIL, String.class, "3");
         _verifyCoerceFail(MAPPER_TO_FAIL, StringWrapper.class, "{\"str\": -5}", "string");
-        _verifyCoerceFail(MAPPER_TO_FAIL, String[].class, "[ 2 ]", "element of `java.lang.String[]`");
+        _verifyCoerceFail(MAPPER_TO_FAIL, String[].class, "[ 2 ]", "to `java.lang.String` value");
     }
 
     /*

src/test/java/com/fasterxml/jackson/databind/convert/DisableCoercions3690Test.java

@@ -0,0 +1,38 @@
+package com.fasterxml.jackson.databind.convert;
+
+import java.util.List;
+
+import com.fasterxml.jackson.databind.*;
+import com.fasterxml.jackson.databind.cfg.CoercionAction;
+import com.fasterxml.jackson.databind.cfg.CoercionInputShape;
+import com.fasterxml.jackson.databind.exc.InvalidFormatException;
+
+public class DisableCoercions3690Test extends BaseMapTest
+{
+    static class Input3690 {
+        public List<String> field;
+    }
+
+    // [databind#3690]
+    public void testFailMessage3690() throws Exception
+    {
+        ObjectMapper mapper = jsonMapperBuilder()
+                .withCoercionConfigDefaults(config -> {
+                    config.setCoercion(CoercionInputShape.Boolean, CoercionAction.Fail)
+                        .setCoercion(CoercionInputShape.Integer, CoercionAction.Fail)
+                        .setCoercion(CoercionInputShape.Float, CoercionAction.Fail)
+                        .setCoercion(CoercionInputShape.String, CoercionAction.Fail)
+                        .setCoercion(CoercionInputShape.Array, CoercionAction.Fail)
+                        .setCoercion(CoercionInputShape.Object, CoercionAction.Fail);
+                })
+                .build();
+        String json = "{ \"field\": [ 1 ] }";
+        try {
+            mapper.readValue(json, Input3690.class);
+            fail("Should not pass");
+        } catch (InvalidFormatException e) {
+            verifyException(e, "Cannot coerce Integer value (1)");
+            verifyException(e, "to `java.lang.String` value");
+        }
+    }
+}