/*
* This file is part of PKM (Persistent Knowledge Monitor).
* Copyright (c) 2020 Capgemini Group, Commissariat à l'énergie atomique et aux énergies alternatives,
* OW2, Sysgo AG, Technikon, Tree Technology, Universitat Politècnica de València.
*
* PKM is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License version 3 as published by
* the Free Software Foundation.
*
* PKM is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with PKM. If not, see <https://www.gnu.org/licenses/>.
*/
/**
* Get documents in a generic manner from several collections of a database
*
* @memberof PKM
* @instance
* @param {string} dbName - database name
* @param {Array.<string>} collection_names - collection names
* @param {Object} [query] - query
* @param {Object} [options] - options
*
* @return {Promise} a promise
*/
function get_documents_spanned(dbName, collection_names, query = {}, options = {})
{
return new Promise(function(resolve, reject)
{
const debug = this.debug;
let pkm = this;
if(debug)
{
console.log('PKM.get_documents_spanned(' + JSON.stringify(dbName) + ',' + JSON.stringify(collection_names) + ',' + JSON.stringify(query) + ',' + JSON.stringify(options) + ')');
}
const query_is_empty = Object.keys(query).length == 0;
function get_documents_spanned_rec(dbName, collection_names, index, query, options)
{
return (index >= collection_names.length) ? Promise.resolve([]) : new Promise(function(resolve, reject)
{
let skip;
let limit;
if(options.skip) skip = options.skip;
if(options.limit) limit = options.limit;
const collection_name = collection_names[index];
let result;
pkm.get_documents(dbName, collection_name, query, options).then((documents) =>
{
result = documents;
}).catch((err) =>
{
const error = require('./error');
if(!error instanceof error.PKM_NotFound)
{
reject(pkm.Error(err));
}
else
{
result = [];
}
}).finally(() =>
{
if(result !== undefined)
{
let new_options = Object.assign({}, options);
if(skip !== undefined) new_options.skip = skip = (skip >= result.length) ? (skip - result.length) : 0;
if(limit !== undefined) new_options.limit = limit = (limit >= result.length) ? (limit - result.length) : 0;
if((index < collection_names.length) && ((limit === undefined) || limit))
{
get_documents_spanned_rec(dbName, collection_names, index + 1, query, new_options).then((documents) =>
{
resolve(result.concat(documents));
}).catch((err) =>
{
reject(err);
});
}
else
{
resolve(result);
}
}
});
}.bind(this));
}
get_documents_spanned_rec(dbName, collection_names, 0, query, Object.assign({}, options)).then((documents) =>
{
if(documents.length || query_is_empty)
{
if(debug)
{
console.log('Found ' + documents.length + ' document(s) from collection(s) ' + collection_names.join(', ') + ' of database \'' + dbName + '\'');
}
resolve(documents);
}
else
{
reject(this.NotFound());
}
}).catch((err) =>
{
reject(this.Error(err));
});
}.bind(this));
}
module.exports.get_documents_spanned = get_documents_spanned;