From 24f1923ff4311736c382e98a5f0b8c5c26097d74 Mon Sep 17 00:00:00 2001
From: Owen Stephens <owen@ostephens.com>
Date: Wed, 21 Feb 2018 23:20:15 +0000
Subject: [PATCH] Return errors not nulls when: wrong number of arguments
 supplied; first argument zero length/empty string

---
 .../google/refine/expr/functions/ToDate.java  | 46 +++++++++----------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/main/src/com/google/refine/expr/functions/ToDate.java b/main/src/com/google/refine/expr/functions/ToDate.java
index b74655cfe..c748be0dc 100644
--- a/main/src/com/google/refine/expr/functions/ToDate.java
+++ b/main/src/com/google/refine/expr/functions/ToDate.java
@@ -50,29 +50,30 @@ import com.google.refine.expr.EvalError;
 import com.google.refine.expr.util.CalendarParser;
 import com.google.refine.expr.util.CalendarParserException;
 import com.google.refine.grel.Function;
+import com.google.refine.grel.ControlFunctionRegistry;
 import com.google.refine.util.ParsingUtilities;
 
 public class ToDate implements Function {
 
     @Override
     public Object call(Properties bindings, Object[] args) {
-        if (args.length == 0) {
-            // missing value, can this happen?
-            return null;
-        }
-        Object arg0 = args[0];
         String o1;
-        if (arg0 instanceof Date) {
-            return arg0;
-        } else if (arg0 instanceof Calendar) {
-            return ((Calendar) arg0).getTime();
-        } else if (arg0 instanceof Long) {
-            o1 =  ((Long) arg0).toString(); // treat integers as years
-        } else if (arg0 instanceof String) {
-            o1 = (String) arg0;
+        if (args.length == 0) {
+            return new EvalError(ControlFunctionRegistry.getFunctionName(this) + " expects at least one argument");
         } else {
-            // ignore cell values that aren't strings
-            return new EvalError("Not a String - cannot parse to date");
+            Object arg0 = args[0];
+            if (arg0 instanceof Date) {
+                return arg0;
+            } else if (arg0 instanceof Calendar) {
+                return ((Calendar) arg0).getTime();
+            } else if (arg0 instanceof Long) {
+                o1 =  ((Long) arg0).toString(); // treat integers as years
+            } else if (arg0 instanceof String && arg0.toString().trim().length() > 0) {
+                o1 = (String) arg0;
+            } else {
+                // ignore cell values that aren't Date, Calendar, Long or String 
+                return new EvalError("Unable to parse as date");
+            }
         }
 
         // "o, boolean month_first (optional)"
@@ -98,13 +99,12 @@ public class ToDate implements Function {
 //                    } catch (DatatypeConfigurationException e2) {     
 //                    }
                 }
-                return new EvalError("Cannot parse to date");
+                return new EvalError("Unable to parse as date");
             }
-        }
-
-        // "o, format1, format2 (optional), ..."
-        Locale locale = Locale.getDefault();
-        if (args.length>=2) {
+        } else if (args.length>=2) {
+            // "o, format1, format2 (optional), ..."
+            Locale locale = Locale.getDefault();
+        
             for (int i=1;i<args.length;i++) {
                 if (!(args[i] instanceof String)) {
                     // skip formats that aren't strings
@@ -156,9 +156,9 @@ public class ToDate implements Function {
                 }
             }
             return new EvalError("Unable to parse as date");
+        } else {
+            return new EvalError("Unable to parse as date");
         }
-
-        return null;
     }