Add 'Add a metric' action which converts question to multiquery

frontend/src/metabase-lib/lib/MultiQuery.js

@@ -40,10 +40,10 @@ function createChildQuery(question: Question, datasetQuery: ChildDatasetQuery):
  * Because each query contained by MultiDatasetQuery should have just a single aggregation, StructuredQueries
  * with two or more aggregations are broken into queries with one of those aggregations in each.
  */
-export function convertToMultiDatasetQuery(datasetQuery: DatasetQuery) {
+export function convertToMultiDatasetQuery(question: Question, datasetQuery: DatasetQuery) {
     const getConvertedQueries = () => {
         if (isStructuredDatasetQuery(datasetQuery)) {
-            const structuredQuery: StructuredQuery = new StructuredQuery(null, datasetQuery);
+            const structuredQuery: StructuredQuery = new StructuredQuery(question, datasetQuery);
             const aggregations = structuredQuery.aggregations();
             const isMultiAggregationQuery = aggregations.length > 1;
 
@@ -56,10 +56,11 @@ export function convertToMultiDatasetQuery(datasetQuery: DatasetQuery) {
                 return aggregations.map((aggregation) => (
                     structuredQuery.clearAggregations().addAggregation(aggregation).datasetQuery()
                 ));
+            } else {
+                return [datasetQuery];
             }
         } else {
-            // Just bypass the native/structured query
-            return [datasetQuery];
+            throw new Error("Native queries can't yet be converted to MultiDatasetQuery")
         }
     }
 

frontend/src/metabase-lib/lib/Query.js

@@ -32,6 +32,11 @@ export default class Query {
         return false;
     }
 
+    // TODO: Decide the behavior of isEditable for multimetric questions
+    isEditable(): boolean {
+        return true;
+    }
+    
     /**
      * Returns the dataset_query object underlying this Query
      */

frontend/src/metabase-lib/lib/Question.js

@@ -184,11 +184,12 @@ export default class Question {
         return this.query().isMulti();
     }
     canConvertToMultiQuery(): boolean {
-        return true;
+        const query = this.query();
+        return query instanceof StructuredQuery && !query.isBareRows();
     }
     convertToMultiQuery(): Question {
         // TODO Atte Keinänen 6/6/17: I want to be 99% sure that this doesn't corrupt the question in any scenario
-        const multiDatasetQuery = convertToMultiDatasetQuery(this._card.dataset_query);
+        const multiDatasetQuery = convertToMultiDatasetQuery(this, this._card.dataset_query);
         return this.setCard(assoc(this._card, "dataset_query", multiDatasetQuery));
     }
 

frontend/src/metabase/qb/components/actions/AddMetricAction.jsx

+/* @flow */
+import StructuredQuery from "metabase-lib/lib/StructuredQuery";
+
+import type {
+    ClickAction,
+    ClickActionProps
+} from "metabase/meta/types/Visualization";
+
+export default ({ question }: ClickActionProps): ClickAction[] => {
+    const isBareRows = question.query() instanceof StructuredQuery && question.query().isBareRows()
+
+    if (question.canConvertToMultiQuery()) {
+        return [
+            {
+                name: "add-metric",
+                title: "Add a metric",
+                icon: "add",
+                question: () => question.convertToMultiQuery()
+            }
+        ];
+    }
+    return [];
+};

frontend/src/metabase/qb/components/actions/index.js

 /* @flow */
 
+import AddMetricAction from "./AddMetricAction";
 import UnderlyingDataAction from "./UnderlyingDataAction";
 import UnderlyingRecordsAction from "./UnderlyingRecordsAction";
 
-export const DEFAULT_ACTIONS = [UnderlyingDataAction, UnderlyingRecordsAction];
+export const DEFAULT_ACTIONS = [AddMetricAction, UnderlyingDataAction, UnderlyingRecordsAction];

frontend/src/metabase/query_builder/components/MetricList.jsx

@@ -15,7 +15,7 @@ const MetricList = ({...props}) => {
     const metrics = question.singleQueries();
     const metricColors = getCardColors(question.card());
 
-    const showAddMetricButton = !hideAddButton && !question.query().isBareRows();
+    const showAddMetricButton = !hideAddButton;
     const canAddMetricToVisualization = _.contains(["line", "area", "bar"], question.display());
     const metricsAreRemovable = !hideClearButton && question.canRemoveMetric();
 

frontend/src/metabase/query_builder/components/QuestionHeader.jsx

@@ -186,12 +186,12 @@ export default class QuestionHeader extends Component {
             onSetCardAttribute
         } = this.props;
 
-        const database = question && question.query().database();
         const card = question.card();
 
         // TODO Atte Keinänen 5/20/17 Add multi-query support to all components that need metadata
-        // This only fetches the table metadata of first available query
-        const tableMetadata = question.query().tableMetadata();
+        // These only fetch the database and table metadata of first available query
+        const tableMetadata = question.singleQueries()[0].tableMetadata();
+        const database = question && question.singleQueries()[0].database();
 
         const SaveNewCardButton = () =>
             <ModalWithTrigger