Provide the Transformer with the field's Type rather than it's Class. The Type

contains generic type information which would allow a transformer to do the
right thing with a field of, say, type Set<Integer>.

If we had unit tests for StringIterable, I'd know that I didn't just break it.
I'd also know that it worked in the first place. :)

src/java/com/samskivert/depot/Transformer.java

@@ -20,6 +20,8 @@
 
 package com.samskivert.depot;
 
+import java.lang.reflect.Type;
+
 /**
  * Transforms a persistent record field into a format that can be read and written by the
  * underlying database. For example, one might transform an enum into a byte, short or integer. Or
@@ -48,5 +50,5 @@ public interface Transformer<F,T>
      *
      * @return the transformed value, which will be stored in a field of the persistent record.
      */
-    F fromPersistent (Class<?> fieldType, T value);
+    F fromPersistent (Type fieldType, T value);
 }

src/java/com/samskivert/depot/Transformers.java

@@ -20,6 +20,9 @@
 
 package com.samskivert.depot;
 
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -65,7 +68,7 @@ public class Transformers
             }
             return buf.toString();
         }
-        public String[] fromPersistent (Class<?> ftype, String value) {
+        public String[] fromPersistent (Type ftype, String value) {
             String[] values = value.replace("\\\t", "%%ESCTAB%%").split("\t");
             for (int ii = 0; ii < values.length; ii++) {
                 values[ii] = values[ii].replace("%%ESCTAB%%", "\t");
@@ -85,7 +88,7 @@ public class Transformers
             return StringIterable.toPersistent0(Arrays.asList(value));
         }
 
-        public String[] fromPersistent (Class<?> ftype, String encoded)
+        public String[] fromPersistent (Type ftype, String encoded)
         {
             if (encoded == null) {
                 return null;
@@ -102,18 +105,20 @@ public class Transformers
             return toPersistent0(value);
         }
 
-        public Iterable<String> fromPersistent (Class<?> ftype, String encoded)
+        public Iterable<String> fromPersistent (Type ftype, String encoded)
         {
             ArrayList<String> value = fromPersistent0(encoded);
+            Type fclass = (ftype instanceof ParameterizedType) ?
+                ((ParameterizedType)ftype).getRawType() : ftype;
             if (value == null ||
-                    ftype == ArrayList.class || ftype == List.class || ftype == Collection.class ||
-                    ftype == Iterable.class) {
+                    fclass == ArrayList.class || fclass == List.class ||
+                    fclass == Collection.class || fclass == Iterable.class) {
                 return value;
             }
-            if (ftype == LinkedList.class) {
+            if (fclass == LinkedList.class) {
                 return Lists.newLinkedList(value);
             }
-            if (ftype == HashSet.class || ftype == Set.class) {
+            if (fclass == HashSet.class || fclass == Set.class) {
                 return Sets.newHashSet(value);
             }
             // else: reflection? See if it's a collection, call the 0-arg constructor, add all

src/java/com/samskivert/depot/impl/FieldMarshaller.java

@@ -705,7 +705,7 @@ public abstract class FieldMarshaller<T>
         }
         @Override public void writeToObject (Object po, T value)
             throws IllegalArgumentException, IllegalAccessException {
-            _field.set(po, _xformer.fromPersistent(_field.getType(), value));
+            _field.set(po, _xformer.fromPersistent(_field.getGenericType(), value));
         }
         @Override public void writeToStatement (PreparedStatement ps, int column, T value)
             throws SQLException {

src/java/com/samskivert/depot/tests/TransformTest.java

@@ -21,6 +21,7 @@
 package com.samskivert.depot.tests;
 
 import java.lang.reflect.Field;
+import java.lang.reflect.Type;
 import java.util.Set;
 
 import org.junit.Test;
@@ -92,7 +93,7 @@ public class TransformTest extends TestBase
             return value.value;
         }
 
-        public CustomType fromPersistent (Class<?> ftype, String value) {
+        public CustomType fromPersistent (Type ftype, String value) {
             return new CustomType(value);
         }
     }
@@ -102,7 +103,7 @@ public class TransformTest extends TestBase
         public Short toPersistent (ShortEnum value) {
             return value.toShort();
         }
-        public ShortEnum fromPersistent (Class<?> ftype, Short value) {
+        public ShortEnum fromPersistent (Type ftype, Short value) {
             @SuppressWarnings("unchecked") Class<Dummy> eclass = (Class<Dummy>)ftype;
             return fromShort(eclass, value);
         }