[internal] Query/AggregateQuery to proto representation (#8177)

* WIP: [internal] Query/AggregateQuery to proto representation.

* using api classes.

* move to a separate file.

* Only return the QueryTarget object.

* declare interface to avoid minification.

* lint fix.

* attempt to avoid minification of ToRunAggregationQueryRequestReturnType.

* allow skipping aliasing.

packages/firestore/src/api.ts

@@ -219,6 +219,10 @@ export {
  */
 export { isBase64Available as _isBase64Available } from './platform/base64';
 export { DatabaseId as _DatabaseId } from './core/database_info';
+export {
+  _internalQueryToProtoQueryTarget,
+  _internalAggregationQueryToProtoRunAggregationQueryRequest
+} from './remote/internal_serializer';
 export {
   cast as _cast,
   validateIsNotUsedTogether as _validateIsNotUsedTogether

packages/firestore/src/remote/internal_serializer.ts

@@ -0,0 +1,89 @@
+/**
+ * @license
+ * Copyright 2017 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { ensureFirestoreConfigured, Firestore } from '../api/database';
+import { AggregateImpl } from '../core/aggregate';
+import { queryToAggregateTarget, queryToTarget } from '../core/query';
+import { AggregateSpec } from '../lite-api/aggregate_types';
+import { Query } from '../lite-api/reference';
+import { cast } from '../util/input_validation';
+import { mapToArray } from '../util/obj';
+
+import { toQueryTarget, toRunAggregationQueryRequest } from './serializer';
+
+/**
+ * @internal
+ * @private
+ *
+ * This function is for internal use only.
+ *
+ * Returns the `QueryTarget` representation of the given query. Returns `null`
+ * if the Firestore client associated with the given query has not been
+ * initialized or has been terminated.
+ *
+ * @param query - The Query to convert to proto representation.
+ */
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export function _internalQueryToProtoQueryTarget(query: Query): any {
+  const firestore = cast(query.firestore, Firestore);
+  const client = ensureFirestoreConfigured(firestore);
+  const serializer = client._onlineComponents?.datastore.serializer;
+  if (serializer === undefined) {
+    return null;
+  }
+  return toQueryTarget(serializer!, queryToTarget(query._query)).queryTarget;
+}
+
+/**
+ * @internal
+ * @private
+ *
+ * This function is for internal use only.
+ *
+ * Returns `RunAggregationQueryRequest` which contains the proto representation
+ * of the given aggregation query request. Returns null if the Firestore client
+ * associated with the given query has not been initialized or has been
+ * terminated.
+ *
+ * @param query - The Query to convert to proto representation.
+ * @param aggregateSpec - The set of aggregations and their aliases.
+ */
+export function _internalAggregationQueryToProtoRunAggregationQueryRequest<
+  AggregateSpecType extends AggregateSpec
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+>(query: Query, aggregateSpec: AggregateSpecType): any {
+  const aggregates = mapToArray(aggregateSpec, (aggregate, alias) => {
+    return new AggregateImpl(
+      alias,
+      aggregate.aggregateType,
+      aggregate._internalFieldPath
+    );
+  });
+  const firestore = cast(query.firestore, Firestore);
+  const client = ensureFirestoreConfigured(firestore);
+  const serializer = client._onlineComponents?.datastore.serializer;
+  if (serializer === undefined) {
+    return null;
+  }
+
+  return toRunAggregationQueryRequest(
+    serializer!,
+    queryToAggregateTarget(query._query),
+    aggregates,
+    /* skipAliasing= */ true
+  ).request;
+}

packages/firestore/src/remote/serializer.ts

@@ -903,7 +903,8 @@ export function toQueryTarget(
 export function toRunAggregationQueryRequest(
   serializer: JsonProtoSerializer,
   target: Target,
-  aggregates: Aggregate[]
+  aggregates: Aggregate[],
+  skipAliasing?: boolean
 ): {
   request: ProtoRunAggregationQueryRequest;
   aliasMap: Record<string, string>;
@@ -919,7 +920,9 @@ export function toRunAggregationQueryRequest(
     // Map all client-side aliases to a unique short-form
     // alias. This avoids issues with client-side aliases that
     // exceed the 1500-byte string size limit.
-    const serverAlias = `aggregate_${aggregationNum++}`;
+    const serverAlias = skipAliasing
+      ? aggregate.alias
+      : `aggregate_${aggregationNum++}`;
     aliasMap[serverAlias] = aggregate.alias;
 
     if (aggregate.aggregateType === 'count') {