Implement optional default value for to_var() Fix function. (#365)

Author: blackwinter

metafix/src/main/java/org/metafacture/metafix/FixMethod.java

@@ -127,7 +127,7 @@ public void apply(final Metafix metafix, final Record record, final List<String>
         @Override
         public void apply(final Metafix metafix, final Record record, final List<String> params, final Map<String, String> options) {
             final Value value = record.get(params.get(0));
-            metafix.getVars().put(params.get(1), Value.isNull(value) ? "" : value.toString());
+            metafix.getVars().put(params.get(1), Value.isNull(value) ? options.getOrDefault(DEFAULT_OPTION, "") : value.toString());
         }
     },
 
@@ -694,6 +694,7 @@ public void apply(final Metafix metafix, final Record record, final List<String>
     private static final String FILEMAP_SEPARATOR_OPTION = "sep_char";
     private static final String FILEMAP_DEFAULT_SEPARATOR = ",";
 
+    private static final String DEFAULT_OPTION = "default";
     private static final String ERROR_STRING_OPTION = "error_string";
 
     private static final Random RANDOM = new Random();

metafix/src/test/java/org/metafacture/metafix/MetafixMethodTest.java

@@ -4087,8 +4087,8 @@ public void shouldTransformStringToBase64() {
     @Test // checkstyle-disable-line JavaNCSS
     public void shouldCreateVariableFromLiteralValue() {
         MetafixTestHelpers.assertFix(streamReceiver, Arrays.asList(
-                "to_var('data.title','testVar')",
-                "add_field('testResult','This is a $[testVar]')"
+                "to_var('data.title', 'testVar')",
+                "add_field('testResult', 'This is a $[testVar]')"
             ),
             i -> {
                 i.startRecord("1");
@@ -4151,4 +4151,33 @@ public void shouldCreateVariableFromLiteralValue() {
         );
     }
 
+    @Test
+    public void shouldCreateVariableFromLiteralValueWithDefault() {
+        MetafixTestHelpers.assertFix(streamReceiver, Arrays.asList(
+                "to_var('data.title', 'testVar', 'default': 'n/a')",
+                "add_field('testResult', 'This is a $[testVar]')"
+            ),
+            i -> {
+                i.startRecord("1");
+                i.startEntity("data");
+                i.literal("title", "test");
+                i.endEntity();
+                i.endRecord();
+                i.startRecord("2");
+                i.endRecord();
+            },
+            o -> {
+                o.get().startRecord("1");
+                o.get().startEntity("data");
+                o.get().literal("title", "test");
+                o.get().endEntity();
+                o.get().literal("testResult", "This is a test");
+                o.get().endRecord();
+                o.get().startRecord("2");
+                o.get().literal("testResult", "This is a n/a");
+                o.get().endRecord();
+            }
+        );
+    }
+
 }