Fix #2693

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -61,6 +61,8 @@ Project: jackson-databind
  (requested by Rafal K)
 #2668: `IllegalArgumentException` thrown for mismatched subclass deserialization
  (reported by nbruno@github)
+#2693: Add convenience methods for creating `List`, `Map` valued `ObjectReader`s
+  (ObjectMapper.readerForListOf())
 - Add `SerializerProvider.findContentValueSerializer()` methods
 
 2.10.4 (not yet released)

src/main/java/com/fasterxml/jackson/databind/ObjectMapper.java

@@ -3951,6 +3951,54 @@ public ObjectReader readerFor(TypeReference<?> type) {
                 null, _injectableValues);
     }
 
+    /**
+     * Factory method for constructing {@link ObjectReader} that will
+     * read values of a type {@code List<type>}.
+     * Functionally same as:
+     *<pre>
+     *    readerFor(type[].class);
+     *</pre>
+     *
+     * @since 2.11
+     */
+    public ObjectReader readerForArrayOf(Class<?> type) {
+        return _newReader(getDeserializationConfig(),
+                _typeFactory.constructArrayType(type), null,
+                null, _injectableValues);
+    }
+
+    /**
+     * Factory method for constructing {@link ObjectReader} that will
+     * read or update instances of a type {@code List<type>}.
+     * Functionally same as:
+     *<pre>
+     *    readerFor(new TypeReference&lt;List&lt;type>>() { });
+     *</pre>
+     *
+     * @since 2.11
+     */
+    public ObjectReader readerForListOf(Class<?> type) {
+        return _newReader(getDeserializationConfig(),
+                _typeFactory.constructCollectionType(List.class, type), null,
+                null, _injectableValues);
+    }
+
+    /**
+     * Factory method for constructing {@link ObjectReader} that will
+     * read or update instances of a type {@code Map<String, type>}
+     * Functionally same as:
+     *<pre>
+     *    readerFor(new TypeReference&lt;Map&lt;String, type>>() { });
+     *</pre>
+     *
+     * @since 2.11
+     */
+    public ObjectReader readerForMapOf(Class<?> type) {
+        return _newReader(getDeserializationConfig(),
+                _typeFactory.constructMapType(Map.class, String.class, type), null,
+                null, _injectableValues);
+    }
+
     /**
      * Factory method for constructing {@link ObjectReader} that will
      * use specified {@link JsonNodeFactory} for constructing JSON trees.

src/test/java/com/fasterxml/jackson/databind/ObjectReaderTest.java

@@ -2,15 +2,14 @@
 
 import java.io.IOException;
 import java.io.StringWriter;
-import java.util.Collections;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
+
 import com.fasterxml.jackson.core.*;
 import com.fasterxml.jackson.core.json.JsonReadFeature;
+
 import com.fasterxml.jackson.databind.cfg.ContextAttributes;
 import com.fasterxml.jackson.databind.deser.DeserializationProblemHandler;
 import com.fasterxml.jackson.databind.exc.MismatchedInputException;
@@ -60,6 +59,36 @@ public void testSimpleAltSources() throws Exception
         }
     }
 
+    // [databind#2693]: convenience read methods:
+    public void testReaderForArrayOf() throws Exception
+    {
+        Object value = MAPPER.readerForArrayOf(ABC.class)
+                .readValue("[ \"A\", \"C\" ]");
+        assertEquals(ABC[].class, value.getClass());
+        ABC[] abcs = (ABC[]) value;
+        assertEquals(2, abcs.length);
+        assertEquals(ABC.A, abcs[0]);
+        assertEquals(ABC.C, abcs[1]);
+    }
+
+    // [databind#2693]: convenience read methods:
+    public void testReaderForListOf() throws Exception
+    {
+        Object value = MAPPER.readerForListOf(ABC.class)
+                .readValue("[ \"B\", \"C\" ]");
+        assertEquals(ArrayList.class, value.getClass());
+        assertEquals(Arrays.asList(ABC.B, ABC.C), value);
+    }
+
+    // [databind#2693]: convenience read methods:
+    public void testReaderForMapOf() throws Exception
+    {
+        Object value = MAPPER.readerForMapOf(ABC.class)
+                .readValue("{\"key\" : \"B\" }");
+        assertEquals(LinkedHashMap.class, value.getClass());
+        assertEquals(Collections.singletonMap("key", ABC.B), value);
+    }
+
     public void testParserFeatures() throws Exception
     {
         final String JSON = "[ /* foo */ 7 ]";

src/test/java/com/fasterxml/jackson/failing/SetterlessList2692Test.java

@@ -0,0 +1,44 @@
+package com.fasterxml.jackson.failing;
+
+import java.util.*;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.BaseMapTest;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class SetterlessList2692Test extends BaseMapTest
+{
+    static class DataBean {
+
+        final String val;
+
+        @JsonCreator
+        public DataBean(@JsonProperty(value = "val") String val) {
+          super();
+          this.val = val;
+        }
+
+        public String getVal() {
+          return val;
+        }
+        
+        public List<String> getList(){
+          return new ArrayList<>();
+        }
+
+        @Override
+        public String toString() {
+          return "DataBean [val=" + val + "]";
+        }
+    }
+
+    public void testIssue2692() throws Exception {
+          ObjectMapper om = newJsonMapper();
+          String json;
+          DataBean out;
+          json = "{\"list\":[\"11\"],\"val\":\"VAL2\"}";
+          out = om.readerFor(DataBean.class).readValue(json);
+          System.out.println("this is ko" + out);
+     }
+}