#261 value with cell access

jxls-poi/src/main/java/org/jxls/transform/poi/PoiCellData.java

@@ -151,7 +151,18 @@ public void writeToCell(Cell cell, Context context, PoiTransformer transformer)
             ((WritableCellValue) evaluationResult).writeToCell(cell, context);
         } else {
             updateCellGeneralInfo(cell);
+
+            ValueWithCellAccess valueWithCellAccess = null;
+            if (evaluationResult instanceof ValueWithCellAccess) {
+                valueWithCellAccess = (ValueWithCellAccess) evaluationResult;
+                evaluationResult = valueWithCellAccess.getValue();
+                valueWithCellAccess.applyBefore(cell);
+            }
             updateCellContents(cell);
+            if (valueWithCellAccess != null) {
+                valueWithCellAccess.applyAfter(cell);
+            }
+
             CellStyle targetCellStyle = cellStyle;
             if (context.getConfig().isIgnoreSourceCellStyle()) {
                 CellStyle dataFormatCellStyle = findCellStyle(evaluationResult, context.getConfig().getCellStyleMap(), transformer);

jxls-poi/src/main/java/org/jxls/transform/poi/PoiUtil.java

@@ -23,17 +23,25 @@ public static void setCellComment(Cell cell, String commentText, String commentA
         Drawing<?> drawing = sheet.createDrawingPatriarch();
         CreationHelper factory = wb.getCreationHelper();
         if (anchor == null) {
-            anchor = factory.createClientAnchor();
-            anchor.setCol1(cell.getColumnIndex() + 1);
-            anchor.setCol2(cell.getColumnIndex() + 3);
-            anchor.setRow1(cell.getRowIndex());
-            anchor.setRow2(cell.getRowIndex() + 2);
+            anchor = createAnchor(cell, 1, 3, 0, 2);
         }
         Comment comment = drawing.createCellComment(anchor);
         comment.setString(factory.createRichTextString(commentText));
         comment.setAuthor(commentAuthor != null ? commentAuthor : "");
         cell.setCellComment(comment);
     }
+
+    public static ClientAnchor createAnchor(Cell cell, int addToCol1, int addToCol2, int addToRow1, int addToRow2) {
+        Sheet sheet = cell.getSheet();
+        Workbook wb = sheet.getWorkbook();
+        CreationHelper factory = wb.getCreationHelper();
+        ClientAnchor anchor = factory.createClientAnchor();
+        anchor.setCol1(cell.getColumnIndex() + addToCol1);
+        anchor.setCol2(cell.getColumnIndex() + addToCol2);
+        anchor.setRow1(cell.getRowIndex() + addToRow1);
+        anchor.setRow2(cell.getRowIndex() + addToRow2);
+        return anchor;
+    }
 
     public WritableCellValue hyperlink(String address, String link, String linkTypeString) {
         return new WritableHyperlink(address, link, linkTypeString);

jxls-poi/src/main/java/org/jxls/transform/poi/ValueWithCellAccess.java

@@ -0,0 +1,12 @@
+package org.jxls.transform.poi;
+
+import org.apache.poi.ss.usermodel.Cell;
+
+public interface ValueWithCellAccess {
+
+    Object getValue();
+
+    void applyBefore(Cell cell);
+
+    void applyAfter(Cell cell);
+}

jxls-poi/src/test/java/org/jxls/TestWorkbook.java

@@ -11,6 +11,7 @@
 import org.apache.poi.ss.usermodel.SheetConditionalFormatting;
 import org.apache.poi.ss.usermodel.Workbook;
 import org.apache.poi.ss.usermodel.WorkbookFactory;
+import org.apache.poi.ss.util.CellAddress;
 import org.apache.poi.ss.util.CellRangeAddress;
 
 /**
@@ -124,6 +125,14 @@ public LocalDateTime getCellValueAsLocalDateTime(int row, int column) {
         }
     }
 
+    public String getCellComment(int row, int column) {
+        try {
+            return sheet.getCellComment(new CellAddress(row - 1, column - 1)).getString().getString();
+        } catch (NullPointerException e) {
+            return null;
+        }
+    }
+
     /**
      * @param row starts with 1
      * @return row height in Twips

jxls-poi/src/test/java/org/jxls/templatebasedtests/Issue17Test.java

@@ -11,6 +11,7 @@
  * Github issue 17: Image and multi sheet
  */
 public class Issue17Test {
+    // ValueWithCellAccessTest uses code of this class.
 
     @Test
     public void test() throws Exception {
@@ -27,7 +28,7 @@ public void test() throws Exception {
         // Each sheet with an image?
     }
 
-    private List<Item> getItems() {
+    static List<Item> getItems() {
         List<Item> items = new ArrayList<>();
         Item item = new Item();
         item.setId("registered_user");

jxls-poi/src/test/java/org/jxls/templatebasedtests/ValueWithCellAccessTest.java

@@ -0,0 +1,103 @@
+package org.jxls.templatebasedtests;
+
+import static org.junit.Assert.assertEquals;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.junit.Test;
+import org.jxls.JxlsTester;
+import org.jxls.TestWorkbook;
+import org.jxls.common.Context;
+import org.jxls.expression.JexlExpressionEvaluator;
+import org.jxls.templatebasedtests.Issue17Test.Item;
+import org.jxls.transform.poi.PoiUtil;
+import org.jxls.transform.poi.ValueWithCellAccess;
+
+/**
+ * This testcase writes for every cell value its origin as a Excel cell comment.
+ */
+public class ValueWithCellAccessTest {
+
+    @Test
+    public void test() throws Exception {
+        // Prepare
+        Context context = new Context();
+        context.putVar("items", Issue17Test.getItems());
+        context.putVar("_f", new Functions(context)); // withSource() method returns ValueWithCellAccess
+
+        // Test
+        JxlsTester tester = JxlsTester.xlsx(getClass());
+        tester.processTemplate(context);
+
+        // Verify
+        try (TestWorkbook w = tester.getWorkbook()) {
+            w.selectSheet(0);
+            // cell values:
+            assertEquals("ANDROID", w.getCellValueAsString(2, 2));
+            assertEquals("JP", w.getCellValueAsString(2, 3));
+            // origins as comments:
+            assertEquals("class=org.jxls.templatebasedtests.Issue17Test$Item\nfield=app_type\nid=registered_user", w.getCellComment(2, 2));
+            assertEquals("class=org.jxls.templatebasedtests.Issue17Test$Item\nfield=country_code\nid=registered_user", w.getCellComment(2, 3));
+        }
+    }
+
+    public static class Functions {
+        private final Context context;
+
+        public Functions(Context ctx) {
+            this.context = ctx;
+        }
+
+        public ValueWithCellAccess withSource(String path) {
+            if (path == null || !path.contains(".")) {
+                throw new RuntimeException("path must not be null and must contain '.'");
+            }
+            int o = path.lastIndexOf(".");
+            String head = path.substring(0, o);
+            String tail = path.substring(o + 1); // field name
+            Item pe = (Item) evaluate(head);
+            Object value;
+            switch (tail) {
+            case "app_type":
+                value = pe.getApp_type();
+                break;
+            case "country_code":
+                value = pe.getCountry_code();
+                break;
+            default:
+                throw new RuntimeException("Unknown field: " + tail);
+            }
+            return new MyValueWithCellAccess(pe, tail, value);
+        }
+
+        private Object evaluate(String expression) {
+            return new JexlExpressionEvaluator(expression).evaluate(context.toMap());
+        }
+    }
+
+    public static class MyValueWithCellAccess implements ValueWithCellAccess {
+        private Item pe;
+        private String fieldName;
+        private Object value;
+
+        public MyValueWithCellAccess(Item pe, String fieldName, Object value) {
+            this.pe = pe;
+            this.fieldName = fieldName;
+            this.value = value;
+        }
+
+        @Override
+        public Object getValue() {
+            return value;
+        }
+
+        @Override
+        public void applyBefore(Cell cell) {
+            String note = "class=" + pe.getClass().getName() + "\nfield=" + fieldName + "\nid=" + pe.getId();
+            PoiUtil.setCellComment(cell, note, "auto", PoiUtil.createAnchor(cell, 1, 3, 0, 4));
+        }
+
+        @Override
+        public void applyAfter(Cell cell) {
+        }
+    }
+}