Simple Chat Room in NodeJS, expressJS and mongoDB in Docker Swarm
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4 years ago
'use strict';
const Aspect = require('./operation').Aspect;
const defineAspects = require('./operation').defineAspects;
const CommandOperationV2 = require('./command_v2');
const decorateWithCollation = require('../utils').decorateWithCollation;
const decorateWithReadConcern = require('../utils').decorateWithReadConcern;
/**
* Return a list of distinct values for the given key across a collection.
*
* @class
* @property {Collection} a Collection instance.
* @property {string} key Field of the document to find distinct values for.
* @property {object} query The query for filtering the set of documents to which we apply the distinct filter.
* @property {object} [options] Optional settings. See Collection.prototype.distinct for a list of options.
*/
class DistinctOperation extends CommandOperationV2 {
/**
* Construct a Distinct operation.
*
* @param {Collection} a Collection instance.
* @param {string} key Field of the document to find distinct values for.
* @param {object} query The query for filtering the set of documents to which we apply the distinct filter.
* @param {object} [options] Optional settings. See Collection.prototype.distinct for a list of options.
*/
constructor(collection, key, query, options) {
super(collection, options);
this.collection = collection;
this.key = key;
this.query = query;
}
/**
* Execute the operation.
*
* @param {Collection~resultCallback} [callback] The command result callback
*/
execute(server, callback) {
const coll = this.collection;
const key = this.key;
const query = this.query;
const options = this.options;
// Distinct command
const cmd = {
distinct: coll.collectionName,
key: key,
query: query
};
// Add maxTimeMS if defined
if (typeof options.maxTimeMS === 'number') {
cmd.maxTimeMS = options.maxTimeMS;
}
// Do we have a readConcern specified
decorateWithReadConcern(cmd, coll, options);
// Have we specified collation
try {
decorateWithCollation(cmd, coll, options);
} catch (err) {
return callback(err, null);
}
super.executeCommand(server, cmd, (err, result) => {
if (err) {
callback(err);
return;
}
callback(null, this.options.full ? result : result.values);
});
}
}
defineAspects(DistinctOperation, [
Aspect.READ_OPERATION,
Aspect.RETRYABLE,
Aspect.EXECUTE_WITH_SELECTION
]);
module.exports = DistinctOperation;