Add new fix method to set variable with element value #282

README.md

@@ -267,6 +267,22 @@ put_vars(
 
 [Java Code](https://github.com/search?type=code&q=repo:metafacture/metafacture-fix+path:FixMethod.java+"+put_vars+{")
 
+##### `to_var`
+
+Defines a single global variable that can be referenced with `$[<variableName>]` and assigns the value of the `<sourceField>`.
+
+```perl
+to_var("<sourceField>", "<variableName>")
+```
+
+Options:
+
+- `default`: Default value if source field does not exist. The option needs to be written in quotation marks because it is a reserved word in Java. (Default: Empty string)
+
+[Example in Playground](https://metafacture.org/playground/?example=to_var)
+
+[Java Code](https://github.com/search?type=code&q=repo:metafacture/metafacture-fix+path:FixMethod.java+"+to_var+{")
+
 #### Record-level functions
 
 ##### `add_field`

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

@@ -123,6 +123,13 @@ public void apply(final Metafix metafix, final Record record, final List<String>
             metafix.getVars().putAll(options);
         }
     },
+    to_var {
+        @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) ? options.getOrDefault(DEFAULT_OPTION, "") : value.asString());
+        }
+    },
 
     // RECORD-LEVEL METHODS:
 
@@ -687,6 +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

@@ -4084,4 +4084,114 @@ 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]')"
+            ),
+            i -> {
+                i.startRecord("1");
+                i.startEntity("data");
+                i.literal("title", "test");
+                i.endEntity();
+                i.endRecord();
+                i.startRecord("2");
+                i.endRecord();
+                i.startRecord("3");
+                i.startEntity("data");
+                i.literal("title", "final-test");
+                i.endEntity();
+                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 ");
+                o.get().endRecord();
+                o.get().startRecord("3");
+                o.get().startEntity("data");
+                o.get().literal("title", "final-test");
+                o.get().endEntity();
+                o.get().literal("testResult", "This is a final-test");
+                o.get().endRecord();
+            }
+        );
+    }
+
+    @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();
+            }
+        );
+    }
+
+    @Test
+    public void shouldNotCreateVariableFromArrayValue() {
+        MetafixTestHelpers.assertExecutionException(IllegalStateException.class, "Expected String, got Array", () ->
+            MetafixTestHelpers.assertFix(streamReceiver, Arrays.asList(
+                    "to_var('data.title', 'testVar')"
+                ),
+                i -> {
+                    i.startRecord("1");
+                    i.startEntity("data");
+                    i.literal("title", "test1");
+                    i.literal("title", "test2");
+                    i.endEntity();
+                    i.endRecord();
+                },
+                o -> {
+                }
+            )
+        );
+    }
+
+    @Test
+    public void shouldNotCreateVariableFromHashValue() {
+        MetafixTestHelpers.assertExecutionException(IllegalStateException.class, "Expected String, got Hash", () ->
+            MetafixTestHelpers.assertFix(streamReceiver, Arrays.asList(
+                    "to_var('data.title', 'testVar')"
+                ),
+                i -> {
+                    i.startRecord("1");
+                    i.startEntity("data");
+                    i.startEntity("title");
+                    i.literal("key", "value");
+                    i.endEntity();
+                    i.endEntity();
+                    i.endRecord();
+                },
+                o -> {
+                }
+            )
+        );
+    }
+
 }