Fix FasterXML#3013: Implement int-to-string coercion config

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

@@ -1371,7 +1371,9 @@ protected java.util.Date _parseDate(String value, DeserializationContext ctxt)
      *
      * @since 2.1
      */
-    protected final String _parseString(JsonParser p, DeserializationContext ctxt) throws IOException
+    protected final String _parseString(JsonParser p, DeserializationContext ctxt,
+            NullValueProvider nullProvider)
+        throws IOException
     {
         if (p.hasToken(JsonToken.VALUE_STRING)) {
             return p.getText();
@@ -1393,9 +1395,23 @@ protected final String _parseString(JsonParser p, DeserializationContext ctxt) t
             return ctxt.extractScalarFromObject(p, this, _valueClass);
         }
 
-        String value = p.getValueAsString();
-        if (value != null) {
-            return value;
+        if (p.hasToken(JsonToken.VALUE_NUMBER_INT)) {
+            final CoercionAction act = _checkIntToStringCoercion(p, ctxt, _valueClass);
+            if (act == CoercionAction.AsNull) {
+                return (String) nullProvider.getNullValue(ctxt);
+            }
+            if (act == CoercionAction.AsEmpty) {
+                return "";
+            }
+        }
+        // allow coercions for other scalar types
+        // 17-Jan-2018, tatu: Related to [databind#1853] avoid FIELD_NAME by ensuring it's
+        //   "real" scalar
+        if (p.currentToken().isScalarValue()) {
+            String text = p.getValueAsString();
+            if (text != null) {
+                return text;
+            }
         }
         return (String) ctxt.handleUnexpectedToken(String.class, p);
     }
@@ -1503,6 +1519,22 @@ protected CoercionAction _checkFloatToIntCoercion(JsonParser p, DeserializationC
         return act;
     }
 
+    /**
+     * @since 2.14
+     */
+    protected CoercionAction _checkIntToStringCoercion(JsonParser p, DeserializationContext ctxt,
+            Class<?> rawTargetType)
+        throws IOException
+    {
+        final CoercionAction act = ctxt.findCoercionAction(LogicalType.Textual,
+                rawTargetType, CoercionInputShape.Integer);
+        if (act == CoercionAction.Fail) {
+            return _checkCoercionFail(ctxt, act, rawTargetType, p.getNumberValue(),
+                    "Integer value (" + p.getText() + ")");
+        }
+        return act;
+    }
+
     /**
      * @since 2.14
      */

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

@@ -165,7 +165,7 @@ public String[] deserialize(JsonParser p, DeserializationContext ctxt) throws IO
                         }
                         value = (String) _nullProvider.getNullValue(ctxt);
                     } else {
-                        value = _parseString(p, ctxt);
+                        value = _parseString(p, ctxt, _nullProvider);
                     }
                 }
                 if (ix >= chunk.length) {
@@ -286,7 +286,7 @@ public String[] deserialize(JsonParser p, DeserializationContext ctxt,
                         }
                         value = (String) _nullProvider.getNullValue(ctxt);
                     } else {
-                        value = _parseString(p, ctxt);
+                        value = _parseString(p, ctxt, _nullProvider);
                     }
                 }
                 if (ix >= chunk.length) {
@@ -335,7 +335,7 @@ private final String[] handleNonArray(JsonParser p, DeserializationContext ctxt)
                     // if coercion failed, we can still add it to an array
                 }
 
-                value = _parseString(p, ctxt);
+                value = _parseString(p, ctxt, _nullProvider);
             }
             return new String[] { value };
         }

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

@@ -215,7 +215,7 @@ public Collection<String> deserialize(JsonParser p, DeserializationContext ctxt,
                     }
                     value = (String) _nullProvider.getNullValue(ctxt);
                 } else {
-                    value = _parseString(p, ctxt);
+                    value = _parseString(p, ctxt, _nullProvider);
                 }
                 result.add(value);
             }
@@ -322,7 +322,7 @@ private final Collection<String> handleNonArray(JsonParser p, DeserializationCon
             }
 
             try {
-                value = (valueDes == null) ? _parseString(p, ctxt) : valueDes.deserialize(p, ctxt);
+                value = (valueDes == null) ? _parseString(p, ctxt, _nullProvider) : valueDes.deserialize(p, ctxt);
             } catch (Exception e) {
                 throw JsonMappingException.wrapWithPath(e, result, result.size());
             }

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

@@ -5,6 +5,7 @@
 import com.fasterxml.jackson.core.*;
 import com.fasterxml.jackson.databind.*;
 import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
+import com.fasterxml.jackson.databind.cfg.CoercionAction;
 import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
 import com.fasterxml.jackson.databind.type.LogicalType;
 
@@ -40,37 +41,11 @@ public String deserialize(JsonParser p, DeserializationContext ctxt) throws IOEx
         if (p.hasToken(JsonToken.VALUE_STRING)) {
             return p.getText();
         }
-        JsonToken t = p.currentToken();
         // [databind#381]
-        if (t == JsonToken.START_ARRAY) {
+        if (p.hasToken(JsonToken.START_ARRAY)) {
             return _deserializeFromArray(p, ctxt);
         }
-        // need to gracefully handle byte[] data, as base64
-        if (t == JsonToken.VALUE_EMBEDDED_OBJECT) {
-            Object ob = p.getEmbeddedObject();
-            if (ob == null) {
-                return null;
-            }
-            if (ob instanceof byte[]) {
-                return ctxt.getBase64Variant().encode((byte[]) ob, false);
-            }
-            // otherwise, try conversion using toString()...
-            return ob.toString();
-        }
-        // 29-Jun-2020, tatu: New! "Scalar from Object" (mostly for XML)
-        if (t == JsonToken.START_OBJECT) {
-            return ctxt.extractScalarFromObject(p, this, _valueClass);
-        }
-        // allow coercions for other scalar types
-        // 17-Jan-2018, tatu: Related to [databind#1853] avoid FIELD_NAME by ensuring it's
-        //   "real" scalar
-        if (t.isScalarValue()) {
-            String text = p.getValueAsString();
-            if (text != null) {
-                return text;
-            }
-        }
-        return (String) ctxt.handleUnexpectedToken(_valueClass, p);
+        return _parseString(p, ctxt, this);
     }
 
     // Since we can never have type info ("natural type"; String, Boolean, Integer, Double):

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

@@ -0,0 +1,115 @@
+package com.fasterxml.jackson.databind.convert;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.BaseMapTest;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ObjectReader;
+import com.fasterxml.jackson.databind.cfg.CoercionAction;
+import com.fasterxml.jackson.databind.cfg.CoercionInputShape;
+import com.fasterxml.jackson.databind.exc.MismatchedInputException;
+import com.fasterxml.jackson.databind.type.LogicalType;
+
+public class CoerceIntToStringTest extends BaseMapTest
+{
+    private final ObjectMapper DEFAULT_MAPPER = newJsonMapper();
+
+    private final ObjectMapper MAPPER_TO_FAIL = jsonMapperBuilder()
+            .withCoercionConfig(LogicalType.Textual, cfg ->
+                    cfg.setCoercion(CoercionInputShape.Integer, CoercionAction.Fail))
+            .build();
+
+    private final ObjectMapper MAPPER_TRY_CONVERT = jsonMapperBuilder()
+            .withCoercionConfig(LogicalType.Textual, cfg ->
+                    cfg.setCoercion(CoercionInputShape.Integer, CoercionAction.TryConvert))
+            .build();
+
+    private final ObjectMapper MAPPER_TO_NULL = jsonMapperBuilder()
+            .withCoercionConfig(LogicalType.Textual, cfg ->
+                    cfg.setCoercion(CoercionInputShape.Integer, CoercionAction.AsNull))
+            .build();
+
+    private final ObjectMapper MAPPER_TO_EMPTY = jsonMapperBuilder()
+            .withCoercionConfig(LogicalType.Textual, cfg ->
+                    cfg.setCoercion(CoercionInputShape.Integer, CoercionAction.AsEmpty))
+            .build();
+
+    public void testDefaultIntToStringCoercion() throws JsonProcessingException
+    {
+        assertSuccessfulIntToStringCoercionWith(DEFAULT_MAPPER);
+    }
+
+    public void testCoerceConfigToConvert() throws JsonProcessingException
+    {
+        assertSuccessfulIntToStringCoercionWith(MAPPER_TRY_CONVERT);
+    }
+
+    public void testCoerceConfigToNull() throws JsonProcessingException
+    {
+        assertNull(MAPPER_TO_NULL.readValue("1", String.class));
+        StringWrapper w = MAPPER_TO_NULL.readValue("{\"str\": -5}", StringWrapper.class);
+        assertNull(w.str);
+        String[] arr = MAPPER_TO_NULL.readValue("[ 2 ]", String[].class);
+        assertEquals(1, arr.length);
+        assertNull(arr[0]);
+    }
+
+    public void testCoerceConfigToEmpty() throws JsonProcessingException
+    {
+        assertEquals("", MAPPER_TO_EMPTY.readValue("3", String.class));
+        StringWrapper w = MAPPER_TO_EMPTY.readValue("{\"str\": -5}", StringWrapper.class);
+        assertEquals("", w.str);
+        String[] arr = MAPPER_TO_EMPTY.readValue("[ 2 ]", String[].class);
+        assertEquals(1, arr.length);
+        assertEquals("", arr[0]);
+    }
+
+    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[]`");
+    }
+
+    /*
+    /********************************************************
+    /* Helper methods
+    /********************************************************
+     */
+
+    private void assertSuccessfulIntToStringCoercionWith(ObjectMapper objectMapper)
+            throws JsonProcessingException
+    {
+        assertEquals("3", objectMapper.readValue("3", String.class));
+        assertEquals("-2", objectMapper.readValue("-2", String.class));
+        {
+            StringWrapper w = objectMapper.readValue("{\"str\": -5}", StringWrapper.class);
+            assertEquals("-5", w.str);
+            String[] arr = objectMapper.readValue("[ 2 ]", String[].class);
+            assertEquals("2", arr[0]);
+        }
+    }
+
+    private void _verifyCoerceFail(ObjectMapper m, Class<?> targetType,
+                                   String doc) throws JsonProcessingException
+    {
+        _verifyCoerceFail(m.reader(), targetType, doc, targetType.getName());
+    }
+
+    private void _verifyCoerceFail(ObjectMapper m, Class<?> targetType,
+                                   String doc, String targetTypeDesc) throws JsonProcessingException
+    {
+        _verifyCoerceFail(m.reader(), targetType, doc, targetTypeDesc);
+    }
+
+    private void _verifyCoerceFail(ObjectReader r, Class<?> targetType,
+                                   String doc, String targetTypeDesc) throws JsonProcessingException
+    {
+        try {
+            r.forType(targetType).readValue(doc);
+            fail("Should not accept Integer for "+targetType.getName()+" when configured to");
+        } catch (MismatchedInputException e) {
+            verifyException(e, "Cannot coerce Integer");
+            verifyException(e, targetTypeDesc);
+        }
+    }
+}