Add option to convert null to #N/A, fixes apache#3777

docs/hop-user-manual/modules/ROOT/pages/getting-started/index.adoc

@@ -20,7 +20,7 @@ under the License.
 :page-pagination-no-back:
 :description: The Apache Hop Getting Started guide walks new Hop users through the Hop concepts and the bare necessities to get started building workflows and pipelines.
 
-== Getting Started
+= Getting Started
 
 This guide walks you through the Hop basics.
 

docs/hop-user-manual/modules/ROOT/pages/pipeline/transforms/formula.adoc

@@ -92,6 +92,7 @@ TIP: The formula will not evaluate a field unless the field pre-exists. Either s
 |Length|field length
 |Precision|field precision
 |Replace value|select a pipeline field from the dropdown to replace that field's value with the formula result. It is not recommended to pre-create a field with a NULL value in a "Get variables" transform as that is considered a hack and is not supported behavior.
+| Set Null to #N/A | By default, Null values will create a blank cell during the calculation. Use this option to insert `#N/A` in the cell
 |===
 
 == Formula Editor

plugins/transforms/formula/src/main/java/org/apache/hop/pipeline/transforms/formula/FormulaDialog.java

@@ -53,6 +53,7 @@
 
 public class FormulaDialog extends BaseTransformDialog {
   private static final Class<?> PKG = FormulaDialog.class;
+  public static final String SYSTEM_COMBO_YES = "System.Combo.Yes";
 
   private TableView wFields;
 
@@ -151,8 +152,12 @@ public String open() {
               false),
           new ColumnInfo(
               BaseMessages.getString(PKG, "FormulaDialog.Replace.Column"),
+              ColumnInfo.COLUMN_TYPE_CCOMBO),
+          new ColumnInfo(
+              BaseMessages.getString(PKG, "FormulaDialog.NA.Column"),
               ColumnInfo.COLUMN_TYPE_CCOMBO,
-              new String[] {}),
+              BaseMessages.getString(PKG, SYSTEM_COMBO_YES),
+              BaseMessages.getString(PKG, "System.Combo.No")),
         };
 
     wFields =
@@ -305,6 +310,11 @@ public void getData() {
           item.setText(5, "" + fn.getValuePrecision());
         }
         item.setText(6, Const.NVL(fn.getReplaceField(), ""));
+        item.setText(
+            7,
+            Boolean.TRUE.equals(fn.isSetNa())
+                ? BaseMessages.getString(PKG, SYSTEM_COMBO_YES)
+                : BaseMessages.getString(PKG, "System.Combo.No"));
       }
     }
 
@@ -340,12 +350,20 @@ private void ok() {
       int valueLength = Const.toInt(item.getText(4), -1);
       int valuePrecision = Const.toInt(item.getText(5), -1);
       String replaceField = item.getText(6);
+      boolean setNa =
+          BaseMessages.getString(PKG, SYSTEM_COMBO_YES).equalsIgnoreCase(item.getText(7));
 
       currentMeta
           .getFormulas()
           .add(
               new FormulaMetaFunction(
-                  fieldName, formulaString, valueType, valueLength, valuePrecision, replaceField));
+                  fieldName,
+                  formulaString,
+                  valueType,
+                  valueLength,
+                  valuePrecision,
+                  replaceField,
+                  setNa));
     }
 
     if (!originalMeta.equals(currentMeta)) {

plugins/transforms/formula/src/main/java/org/apache/hop/pipeline/transforms/formula/FormulaMetaFunction.java

@@ -18,9 +18,13 @@
 package org.apache.hop.pipeline.transforms.formula;
 
 import java.util.Objects;
+import lombok.Getter;
+import lombok.Setter;
 import org.apache.hop.core.row.value.ValueMetaFactory;
 import org.apache.hop.metadata.api.HopMetadataProperty;
 
+@Getter
+@Setter
 public class FormulaMetaFunction {
   public static final String XML_TAG = "formula";
 
@@ -54,6 +58,9 @@ public class FormulaMetaFunction {
       injectionKeyDescription = "FormulaMeta.Injection.ReplaceField")
   private String replaceField;
 
+  @HopMetadataProperty(key = "set_na", injectionKeyDescription = "FormulaMeta.Injection.setNa")
+  private boolean setNa;
+
   /** This value will be discovered on runtime and need not to be persisted into xml or rep. */
   @SuppressWarnings("java:S2065") // disable sonar warning on transient
   private transient boolean needDataConversion = false;
@@ -72,13 +79,15 @@ public FormulaMetaFunction(
       int valueType,
       int valueLength,
       int valuePrecision,
-      String replaceField) {
+      String replaceField,
+      boolean setNa) {
     this.fieldName = fieldName;
     this.formula = formula;
     this.valueType = valueType;
     this.valueLength = valueLength;
     this.valuePrecision = valuePrecision;
     this.replaceField = replaceField;
+    this.setNa = setNa;
 
     ValueMetaFactory.getIdForValueMeta("Boolean");
   }
@@ -90,7 +99,8 @@ public FormulaMetaFunction() {
 
   @Override
   public int hashCode() {
-    return Objects.hash(fieldName, formula, valueType, valueLength, valuePrecision, replaceField);
+    return Objects.hash(
+        fieldName, formula, valueType, valueLength, valuePrecision, replaceField, setNa);
   }
 
   @Override
@@ -102,102 +112,4 @@ public Object clone() {
       return null;
     }
   }
-
-  /**
-   * @return Returns the fieldName.
-   */
-  public String getFieldName() {
-    return fieldName;
-  }
-
-  /**
-   * @param fieldName The fieldName to set.
-   */
-  public void setFieldName(String fieldName) {
-    this.fieldName = fieldName;
-  }
-
-  /**
-   * @return Returns the valueLength.
-   */
-  public int getValueLength() {
-    return valueLength;
-  }
-
-  /**
-   * @param valueLength The valueLength to set.
-   */
-  public void setValueLength(int valueLength) {
-    this.valueLength = valueLength;
-  }
-
-  /**
-   * @return Returns the valuePrecision.
-   */
-  public int getValuePrecision() {
-    return valuePrecision;
-  }
-
-  /**
-   * @param valuePrecision The valuePrecision to set.
-   */
-  public void setValuePrecision(int valuePrecision) {
-    this.valuePrecision = valuePrecision;
-  }
-
-  /**
-   * @return Returns the valueType.
-   */
-  public int getValueType() {
-    return valueType;
-  }
-
-  /**
-   * @param valueType The valueType to set.
-   */
-  public void setValueType(int valueType) {
-    this.valueType = valueType;
-  }
-
-  /**
-   * @return the formula
-   */
-  public String getFormula() {
-    return formula;
-  }
-
-  /**
-   * @param formula the formula to set
-   */
-  public void setFormula(String formula) {
-    this.formula = formula;
-  }
-
-  /**
-   * @return the replaceField
-   */
-  public String getReplaceField() {
-    return replaceField;
-  }
-
-  /**
-   * @param replaceField the replaceField to set
-   */
-  public void setReplaceField(String replaceField) {
-    this.replaceField = replaceField;
-  }
-
-  /**
-   * @return the needDataConversion
-   */
-  public boolean isNeedDataConversion() {
-    return needDataConversion;
-  }
-
-  /**
-   * @param needDataConversion the needDataConversion to set
-   */
-  public void setNeedDataConversion(boolean needDataConversion) {
-    this.needDataConversion = needDataConversion;
-  }
 }

plugins/transforms/formula/src/main/java/org/apache/hop/pipeline/transforms/formula/util/FormulaParser.java

@@ -121,7 +121,11 @@ public CellValue getFormulaValue() throws HopValueException {
           cell.setCellValue(rowMeta.getString(dataRow, fieldPosition));
         }
       } else {
-        cell.setBlank();
+        if (formulaMetaFunction.isSetNa()) {
+          cell.setCellFormula("NA()");
+        } else {
+          cell.setBlank();
+        }
       }
 
       fieldIndex++;

plugins/transforms/formula/src/main/resources/org/apache/hop/pipeline/transforms/formula/messages/messages_en_US.properties

@@ -37,6 +37,7 @@ FormulaDialog.NewField.Column = New field
 FormulaDialog.Precision.Column = Precision
 FormulaDialog.Remove.Column = Remove
 FormulaDialog.Replace.Column = Replace value
+FormulaDialog.NA.Column = Set Null to #N/A
 FormulaDialog.SelectCalculationType.Message = Select the calculation type to perform
 FormulaDialog.SelectCalculationType.Title = Select the calculation type
 FormulaDialog.Shell.Title=Formula
@@ -50,6 +51,7 @@ FormulaMeta.Injection.Formula = Formula
 FormulaMeta.Injection.Formulas = Formulas
 FormulaMeta.Injection.FormulaString = Formula
 FormulaMeta.Injection.ReplaceField = Replace Field 
+FormulaMeta.Injection.setNa = Convert null to #N/A
 FormulaMeta.Injection.ValueLength = Value Length
 FormulaMeta.Injection.ValuePrecision = Value Precision
 FormulaMeta.Injection.ValueType = Value Type