Fix bug: http://code.google.com/p/google-visualization-java/issues/detail?id=4

Author: [email protected]

src/main/java/com/google/visualization/datasource/util/SqlDataSourceHelper.java

@@ -34,10 +34,12 @@
 import com.google.visualization.datasource.query.AggregationColumn;
 import com.google.visualization.datasource.query.AggregationType;
 import com.google.visualization.datasource.query.ColumnColumnFilter;
+import com.google.visualization.datasource.query.ColumnIsNullFilter;
 import com.google.visualization.datasource.query.ColumnSort;
 import com.google.visualization.datasource.query.ColumnValueFilter;
 import com.google.visualization.datasource.query.ComparisonFilter;
 import com.google.visualization.datasource.query.CompoundFilter;
+import com.google.visualization.datasource.query.NegationFilter;
 import com.google.visualization.datasource.query.Query;
 import com.google.visualization.datasource.query.QueryFilter;
 import com.google.visualization.datasource.query.QueryGroup;
@@ -284,11 +286,18 @@ static void appendWhereClause(Query query, StrBuilder queryStringBuilder) {
   private static StrBuilder buildWhereClauseRecursively(QueryFilter queryFilter) {
     StrBuilder whereClause = new StrBuilder();
 
-    // Base case of the recursion: the filter is a comparison filter.
-    if (queryFilter instanceof ComparisonFilter) {
+    // Base case of the recursion: the filter is not a compound filter.
+    if (queryFilter instanceof ColumnIsNullFilter) {
+      buildWhereClauseForIsNullFilter(whereClause, queryFilter);
+    } else if (queryFilter instanceof ComparisonFilter) {
       buildWhereCluaseForComparisonFilter(whereClause, queryFilter);
+    } else if (queryFilter instanceof NegationFilter) {
+      whereClause.append("(NOT ");
+      whereClause.append(buildWhereClauseRecursively(
+          ((NegationFilter) queryFilter).getSubFilter()));
+      whereClause.append(")");
     } else {
-      // The Recursion step: queryFilter is a CompoundFilter.
+      // queryFilter is a CompoundFilter.
       CompoundFilter compoundFilter = (CompoundFilter) queryFilter;
 
       int numberOfSubFilters = compoundFilter.getSubFilters().size();
@@ -315,6 +324,19 @@ private static StrBuilder buildWhereClauseRecursively(QueryFilter queryFilter) {
     return whereClause;
   }
 
+  /**
+   * Builds a WHERE clause for is-null filter.
+   * 
+   * @param whereClause A string builder representing the WHERE clause of the SQL query.
+   * @param queryFilter The query filter.
+   */
+  private static void buildWhereClauseForIsNullFilter(StrBuilder whereClause,
+      QueryFilter queryFilter) {
+    ColumnIsNullFilter filter = (ColumnIsNullFilter) queryFilter;
+ 
+    whereClause.append("(").append(filter.getColumn().getId()).append(" IS NULL)");
+  }
+
   /**
    * Builds the WHERE clause for comparison filter. This is the base case of
    * the recursive building of the WHERE clause of the sql query.

src/test/java/com/google/visualization/datasource/util/SqlDataSourceHelperTest.java

@@ -29,9 +29,11 @@
 import com.google.visualization.datasource.query.AggregationColumn;
 import com.google.visualization.datasource.query.AggregationType;
 import com.google.visualization.datasource.query.ColumnColumnFilter;
+import com.google.visualization.datasource.query.ColumnIsNullFilter;
 import com.google.visualization.datasource.query.ColumnValueFilter;
 import com.google.visualization.datasource.query.ComparisonFilter;
 import com.google.visualization.datasource.query.CompoundFilter;
+import com.google.visualization.datasource.query.NegationFilter;
 import com.google.visualization.datasource.query.Query;
 import com.google.visualization.datasource.query.QueryFilter;
 import com.google.visualization.datasource.query.QueryGroup;
@@ -208,6 +210,22 @@ public void testBuildWhereClause() {
     SqlDataSourceHelper.appendWhereClause(query, queryStringBuilder);
     assertEquals(queryStringBuilder.toString(), "WHERE ((ID=Salary)) ",
         queryStringBuilder.toString());
+    
+    // Check "is null".
+    ColumnIsNullFilter isNullFilter = new ColumnIsNullFilter(new SimpleColumn("ID"));
+    query.setFilter(isNullFilter);
+    queryStringBuilder = new StrBuilder();
+    SqlDataSourceHelper.appendWhereClause(query, queryStringBuilder);
+    assertEquals("WHERE (ID IS NULL) ", queryStringBuilder.toString());
+
+    // Check negation.
+    NegationFilter negationFilter =
+        new NegationFilter(new ColumnColumnFilter(new SimpleColumn("ID"),
+        new SimpleColumn("Salary"), ComparisonFilter.Operator.EQ));
+    query.setFilter(negationFilter);
+    queryStringBuilder = new StrBuilder();
+    SqlDataSourceHelper.appendWhereClause(query, queryStringBuilder);
+    assertEquals("WHERE (NOT (ID=Salary)) ", queryStringBuilder.toString());
   }
 
   /**