Add IS NOT NULL and IS NULL as filter options (apache#5375)

* wip

* disable value selector on IS NOT NULL or NOT NULL

* remove this

(cherry picked from commit e79bb92)

superset/assets/src/explore/AdhocFilter.js

@@ -21,6 +21,8 @@ const OPERATORS_TO_SQL = {
   'not in': 'not in',
   LIKE: 'like',
   regex: 'regex',
+  'IS NOT NULL': 'IS NOT NULL',
+  'IS NULL': 'IS NULL',
 };
 
 function translateToSql(adhocMetric, { useSimple } = {}) {
@@ -84,6 +86,13 @@ export default class AdhocFilter {
 
   isValid() {
     if (this.expressionType === EXPRESSION_TYPES.SIMPLE) {
+      if (this.operator === 'IS NOT NULL' || this.operator === 'IS NULL') {
+        return !!(
+          this.operator &&
+          this.subject
+        );
+      }
+
       return !!(
         this.operator &&
         this.subject &&

superset/assets/src/explore/components/AdhocFilterEditPopoverSimpleTabContent.jsx

@@ -274,6 +274,7 @@ export default class AdhocFilterEditPopoverSimpleTabContent extends React.Compon
                 showHeader={false}
                 noResultsText={t('type a value here')}
                 refFunc={this.multiComparatorRef}
+                disabled={adhocFilter.operator === 'IS NOT NULL' || adhocFilter.operator === 'IS NULL'}
               /> :
               <input
                 ref={this.focusComparator}

superset/assets/src/explore/components/AdhocMetricEditPopover.jsx

@@ -200,7 +200,6 @@ export default class AdhocMetricEditPopover extends React.Component {
 
     const stateIsValid = adhocMetric.isValid();
     const hasUnsavedChanges = !adhocMetric.equals(propsAdhocMetric);
-
     return (
       <Popover
         id="metrics-edit-popover"

superset/assets/src/explore/constants.js

@@ -18,6 +18,8 @@ export const OPERATORS = {
   'not in': 'not in',
   LIKE: 'LIKE',
   regex: 'regex',
+  'IS NOT NULL': 'IS NOT NULL',
+  'IS NULL': 'IS NULL',
 };
 
 export const TABLE_ONLY_OPERATORS = [OPERATORS.LIKE];