Issue 291: Allow org.h2.value.Value as FUNCTION ALIAS params and return value.

h2/src/docsrc/html/changelog.html

@@ -18,7 +18,8 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>Issue 265: Linked tables: auto-reconnect if the backside connection is lost
+<ul><li>Issue 291: Allow org.h2.value.Value as FUNCTION ALIAS params and return value.
+</li><li>Issue 265: Linked tables: auto-reconnect if the backside connection is lost
     (workaround for the MySQL problem that disconnects after 8 hours of inactivity).
 </li><li>Linked tables: the index conditions was sometimes not used when querying the remote database.
 </li><li>Issue 294: OSGi: the versions were missing in manifest package exports.

h2/src/docsrc/html/features.html

@@ -1475,11 +1475,12 @@ to use <code>java.lang.Integer</code> instead.
 </p>
 <p>
 SQL types are mapped to Java classes and vice-versa as in the JDBC API. For details, see <a href="datatypes.html">Data Types</a>.
-There are two special cases: <code>java.lang.Object</code> is mapped to
+There are a few special cases: <code>java.lang.Object</code> is mapped to
 <code>OTHER</code> (a serialized object). Therefore,
 <code>java.lang.Object</code> can not be used
 to match all SQL types (matching all SQL types is not supported). The second special case is <code>Object[]</code>:
 arrays of any class are mapped to <code>ARRAY</code>.
+Objects of type <code>org.h2.value.Value</code> (the internal value class) are passed through without conversion.
 </p>
 
 <h3>Functions That Require a Connection</h3>

h2/src/main/org/h2/engine/FunctionAlias.java

@@ -349,8 +349,13 @@ public class FunctionAlias extends SchemaObjectBase {
                 }
                 int type = DataType.getTypeFromClass(paramClass);
                 Value v = args[a].getValue(session);
-                v = v.convertTo(type);
-                Object o = v.getObject();
+                Object o;
+                if (Value.class.isAssignableFrom(paramClass)) {
+                    o = v;
+                } else {
+                    v = v.convertTo(type);
+                    o = v.getObject();
+                }
                 if (o == null) {
                     if (paramClass.isPrimitive()) {
                         if (columnList) {
@@ -401,6 +406,9 @@ public class FunctionAlias extends SchemaObjectBase {
                 } catch (Exception e) {
                     throw DbException.convert(e);
                 }
+                if (Value.class.isAssignableFrom(method.getReturnType())) {
+                    return (Value) returnValue;
+                }
                 Value ret = DataType.convertToValue(session, returnValue, dataType);
                 return ret.convertTo(dataType);
             } finally {

h2/src/test/org/h2/test/db/TestFunctions.java

@@ -29,6 +29,7 @@ import org.h2.test.TestBase;
 import org.h2.tools.SimpleResultSet;
 import org.h2.util.IOUtils;
 import org.h2.util.New;
+import org.h2.value.Value;
 
 /**
  * Tests for user defined functions and aggregates.
@@ -63,10 +64,30 @@ public class TestFunctions extends TestBase implements AggregateFunction {
         testAggregate();
         testFunctions();
         testFileRead();
+        testValue();
         deleteDb("functions");
         IOUtils.deleteRecursive(TEMP_DIR, true);
     }
 
+    private void testValue() throws SQLException {
+        Connection conn = getConnection("functions");
+        Statement stat = conn.createStatement();
+        ResultSet rs;
+        stat.execute("create alias TO_CHAR for \"" + getClass().getName() + ".toChar\"");
+        rs = stat.executeQuery("call TO_CHAR(TIMESTAMP '2001-02-03 04:05:06', 'format')");
+        rs.next();
+        assertEquals("2001-02-03 04:05:06.0", rs.getString(1));
+        stat.execute("drop alias TO_CHAR");
+        conn.close();
+    }
+
+    public static Value toChar(Value... args) {
+        if (args.length == 0) {
+            return null;
+        }
+        return args[0].convertTo(Value.STRING);
+    }
+
     private void testDefaultConnection() throws SQLException {
         Connection conn = getConnection("functions;DEFAULT_CONNECTION=TRUE");
         Statement stat = conn.createStatement();