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count_documents.ts
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count_documents.ts
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import type { Document } from '../bson';
import type { Collection } from '../collection';
import type { Server } from '../sdam/server';
import type { ClientSession } from '../sessions';
import { AggregateOperation, type AggregateOptions } from './aggregate';
/** @public */
export interface CountDocumentsOptions extends AggregateOptions {
/** The number of documents to skip. */
skip?: number;
/** The maximum amounts to count before aborting. */
limit?: number;
}
/** @internal */
export class CountDocumentsOperation extends AggregateOperation<number> {
constructor(collection: Collection, query: Document, options: CountDocumentsOptions) {
const pipeline = [];
pipeline.push({ $match: query });
if (typeof options.skip === 'number') {
pipeline.push({ $skip: options.skip });
}
if (typeof options.limit === 'number') {
pipeline.push({ $limit: options.limit });
}
pipeline.push({ $group: { _id: 1, n: { $sum: 1 } } });
super(collection.s.namespace, pipeline, options);
}
override async execute(server: Server, session: ClientSession | undefined): Promise<number> {
const result = await super.execute(server, session);
// NOTE: We're avoiding creating a cursor here to reduce the callstack.
const response = result as unknown as Document;
if (response.cursor == null || response.cursor.firstBatch == null) {
return 0;
}
const docs = response.cursor.firstBatch;
return docs.length ? docs[0].n : 0;
}
}