NULL handling, quote(), DISTINCT ON and transaction wrapper
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// Простенький "селект билдер" по мотивам MediaWiki-овского, успешно юзаю подобный в PHP уже лет 8
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// (c) Виталий Филиппов, 2019
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// Версия 2019-06-05
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// Версия 2019-07-04
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// В PHP, правда, прикольнее - там в массиве можно смешивать строковые и численные ключи,
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// благодаря чему можно писать $where = [ 't1.a=t2.a', 't2.b' => [ 1, 2, 3 ] ]
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@ -25,7 +25,14 @@ const MS_VALUE = 6;
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function select_builder(tables, fields, where, options)
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{
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options = options||{};
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let sql = 'SELECT ', bind = [];
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if (options['DISTINCT ON'] || options.distinct_on)
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{
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let group = options['DISTINCT ON'] || options.distinct_on;
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group = group instanceof Array ? group : [ group ];
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sql += 'DISTINCT ON ('+group.join(', ')+') ';
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}
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if (fields instanceof Array)
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{
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sql += fields.join(', ');
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@ -54,7 +61,6 @@ function select_builder(tables, fields, where, options)
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sql += ' AND '+t.moreWhere.sql;
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bind.push.apply(bind, t.moreWhere.bind);
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}
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options = options||{};
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if (options['GROUP BY'] || options.group_by)
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{
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let group = options['GROUP BY'] || options.group_by;
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@ -168,7 +174,7 @@ function tables_builder(tables)
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// - key does not contain '?', value is an empty array => just (key)
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// - key contains '?', value is a scalar or non-empty array => (key) with bind params (...value)
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// - key is numeric, then value is treated as in array
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function where_or_set(fields, where)
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function where_or_set(fields, for_condition)
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{
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if (typeof fields == 'string')
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{
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@ -205,30 +211,43 @@ function where_or_set(fields, where)
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v = v instanceof Array ? v : [ v ];
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if (v.length == 1 && v[0] == null)
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{
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w.push(where ? k+' is null' : k+' = null');
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w.push(for_condition ? k+' is null' : k+' = null');
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}
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else
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{
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if ((v.length > 1 || v[0] instanceof Array) && !where)
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// a IN (...) or (a, b) IN ((...), ...)
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if ((v.length > 1 || v[0] instanceof Array) && !for_condition)
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{
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throw new Error('IN syntax can only be used inside WHERE');
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}
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if (v[0] instanceof Array)
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{
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// (a, b) in (...)
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// (a, b) in ((...), ...)
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w.push(k + ' in (' + v.map(vi => '('+vi.map(() => '?').join(', ')+')') + ')');
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v.map(vi => bind.push.apply(bind, vi));
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}
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else if (!for_condition)
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{
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w.push(k+' = ?');
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bind.push(v[0]);
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}
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else
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{
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w.push(v.length == 1
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? k + ' = ?'
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: k + ' in (' + v.map(() => '?').join(', ') + ')');
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bind.push.apply(bind, v);
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let n = v.length;
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v = v.filter(vi => vi != null);
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if (v.length > 0)
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{
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w.push(k+' in (' + v.map(() => '?').join(', ') + ')' + (n > v.length ? ' or '+k+' is null' : ''));
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bind.push.apply(bind, v);
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}
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else if (n > 0)
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{
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w.push(k+' is null');
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}
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}
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}
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}
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if (!where)
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if (!for_condition)
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{
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// SET
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return { sql: w.join(', '), bind };
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@ -299,6 +318,19 @@ function split_using(tables)
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return { what, using: Object.keys(tables).length > 0 ? tables : null, moreWhere };
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}
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function quote(v)
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{
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if (!pg_escape)
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pg_escape = require('pg-escape');
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if (v == null)
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return 'null';
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else if (typeof v == 'object')
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v = JSON.stringify(v);
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else if (typeof v == 'number')
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return v;
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return '\''+pg_escape.string(v)+'\'';
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}
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// Превратить bind пераметры, выраженные как ?, в вид $n (как в node-postgres)
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function _positional(sql)
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{
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@ -322,12 +354,12 @@ function _inline(sql, bind)
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if (!m1)
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return m;
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let v = bind[i++];
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if (typeof v == 'object')
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if (v == null)
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return 'null';
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else if (typeof v == 'object')
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v = JSON.stringify(v);
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else if (typeof v == 'number')
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return v;
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else if (v == null)
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return 'null';
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return '\''+pg_escape.string(v)+'\'';
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}
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);
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@ -337,8 +369,17 @@ function _inline(sql, bind)
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// dbh: Connection
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async function select(dbh, tables, fields, where, options, format)
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{
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let { sql, bind } = select_builder(tables, fields, where, options);
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let data = await dbh.query(sql, bind);
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let sql_text;
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if (arguments.length == 2 || arguments.length == 3)
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{
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sql_text = tables instanceof Text ? tables : new Text(tables, []);
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format = fields;
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}
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else
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{
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sql_text = select_builder(tables, fields, where, options);
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}
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let data = await dbh.query(sql_text.sql, sql_text.bind);
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if ((format & MS_LIST) || (format & MS_COL))
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data = data.rows.map(r => Object.values(r));
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else
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@ -494,40 +535,92 @@ class Text
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}
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}
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class ConnectionBase
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{
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async select(tables, fields, where, options, format)
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{
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return arguments.length <= 2
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? await select(this, tables, fields)
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: await select(this, tables, fields, where, options, format);
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}
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async insert(table, rows, options)
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{
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return await insert(this, table, rows, options);
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}
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async update(table, set, where, options)
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{
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return await update(this, table, set, where, options);
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}
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async delete(table, where, options)
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{
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return await _delete(this, table, where, options);
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}
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}
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// Обёртка PostgreSQL-подключения
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// Автоматически переподключается при отвале
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class Connection
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class Connection extends ConnectionBase
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{
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constructor(config, init_callback)
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constructor(config)
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{
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super();
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this.config = config;
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this.init_callback = init_callback;
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this.init_connect = [];
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this.in_transaction = null;
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this.transaction_queue = [];
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this.onerror = (e) =>
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{
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console.warn(e);
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console.warn('Database connection dropped. Reconnecting');
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this.dbh = null;
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this.connection_lost = true;
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this.connect();
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};
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this.quote = quote;
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}
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getConnection()
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{
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return this.dbh;
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}
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async runWhenConnected(cb)
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{
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if (this.dbh)
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{
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await cb(this);
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}
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this.init_connect.push(cb);
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}
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dontRunWhenConnected(cb)
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{
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this.init_connect = this.init_connect.filter(c => c != cb);
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}
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async connect()
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{
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if (this.dbh)
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{
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return this.dbh;
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}
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let retry = this.config.retry || 30;
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// eslint-disable-next-line no-constant-condition
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while (true)
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{
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try
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{
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this.dbh = new pg.Client(this.config);
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await this.dbh.connect();
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if (this.init_callback)
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for (const cb of this.init_connect)
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{
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this.init_callback();
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await cb(this);
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}
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this.dbh.on('error', this.onerror);
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return;
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return this.dbh;
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}
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catch (e)
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{
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@ -536,49 +629,117 @@ class Connection
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await new Promise((r, j) => setTimeout(r, retry*1000));
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}
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}
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return this.dbh;
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}
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async begin()
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{
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if (this.in_transaction)
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{
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// Если уже кто-то активен - ждём его
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await new Promise((resolve, reject) => this.transaction_queue.push(resolve));
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}
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this.in_transaction = new Transaction(this);
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await this._query('begin');
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return this.in_transaction;
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}
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async query(sql, bind)
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{
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if (!this.dbh)
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await this.connect();
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console.log('> '+(bind && bind.length ? _inline(sql, bind) : sql));
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return await this.dbh.query(_positional(sql), bind);
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if (sql.length == 5 && sql.toLowerCase() == 'begin')
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{
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throw new Error('Do not use transactions in asynchronous code directly!');
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}
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if (this.in_transaction)
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{
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// Если уже кто-то активен - ждём его
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await new Promise((resolve, reject) => this.transaction_queue.push(resolve));
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}
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const r = await this._query(sql, bind);
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// Если есть ещё кто-то в очереди - пусть проходит
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this._next_txn();
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return r;
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}
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async select(tables, fields, where, options, format)
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_next_txn()
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{
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this.in_transaction = null;
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const next = this.transaction_queue.shift();
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if (next)
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next();
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}
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async _query(sql, bind)
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{
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if (!this.dbh)
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await this.connect();
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return await select(this, tables, fields, where, options, format);
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if (this.in_transaction && this.connection_lost)
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{
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this._next_txn();
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throw new Error('Connection lost while in transaction');
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}
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this.connection_lost = false;
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if (this.config.log_queries)
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console.log('> '+(bind && bind.length ? _inline(sql, bind) : sql));
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try
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{
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if (!this.in_transaction)
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{
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this.in_transaction = true;
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}
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const r = await this.dbh.query(bind && bind.length ? _positional(sql) : sql, bind);
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if (this.in_transaction === true)
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{
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this.in_transaction = false;
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}
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return r;
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}
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catch (e)
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{
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// в postgresql надо откатывать всю транзакцию при любой ошибке
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if (this.in_transaction === true)
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{
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this.in_transaction = false;
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}
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if (this.in_transaction)
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{
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await this.in_transaction.query('rollback');
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}
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else
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{
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if (this.config.log_queries)
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console.log('> rollback');
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await this.dbh.query('rollback');
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}
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throw e;
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}
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}
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}
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class Transaction extends ConnectionBase
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{
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constructor(dbh)
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{
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super();
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this.dbh = dbh;
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}
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async insert(table, rows, options)
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async query(sql, bind)
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{
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if (!this.dbh)
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await this.connect();
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return await insert(this, table, rows, options);
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}
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async update(table, set, where, options)
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{
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if (!this.dbh)
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await this.connect();
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return await update(this, table, set, where, options);
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}
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async delete(table, where, options)
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{
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if (!this.dbh)
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await this.connect();
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return await _delete(this, table, where, options);
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// Здесь уже ждать никого не надо, т.к. если мы сюда попали - то уже дождались своей очереди априори
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const r = await this.dbh._query(sql, bind);
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if (sql.length == 6 && sql.toLowerCase() == 'commit' ||
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sql.length == 8 && sql.toLowerCase() == 'rollback')
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{
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this.dbh._next_txn();
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}
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return r;
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}
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}
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module.exports = {
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select_builder,
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where_builder,
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quote,
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quote_into: _inline,
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quote_positional: _positional,
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select,
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