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42 lines
1.0 KiB
42 lines
1.0 KiB
5 years ago
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'use strict';
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const AggregateOperation = require('./aggregate');
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class CountDocumentsOperation extends AggregateOperation {
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constructor(collection, query, options) {
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const pipeline = [{ $match: query }];
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if (typeof options.skip === 'number') {
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pipeline.push({ $skip: options.skip });
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}
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if (typeof options.limit === 'number') {
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pipeline.push({ $limit: options.limit });
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}
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pipeline.push({ $group: { _id: 1, n: { $sum: 1 } } });
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super(collection, pipeline, options);
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}
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execute(server, callback) {
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super.execute(server, (err, result) => {
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if (err) {
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callback(err, null);
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return;
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}
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// NOTE: We're avoiding creating a cursor here to reduce the callstack.
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const response = result.result;
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if (response.cursor == null || response.cursor.firstBatch == null) {
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callback(null, 0);
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return;
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}
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const docs = response.cursor.firstBatch;
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callback(null, docs.length ? docs[0].n : 0);
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});
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}
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}
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module.exports = CountDocumentsOperation;
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