1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/libraries/mondelefant/mondelefant.lua	Sun Oct 25 12:00:00 2009 +0100
     1.3 @@ -0,0 +1,845 @@
     1.4 +#!/usr/bin/env lua
     1.5 +
     1.6 +
     1.7 +---------------------------
     1.8 +-- module initialization --
     1.9 +---------------------------
    1.10 +
    1.11 +local _G              = _G
    1.12 +local _VERSION        = _VERSION
    1.13 +local assert          = assert
    1.14 +local collectgarbage  = collectgarbage
    1.15 +local dofile          = dofile
    1.16 +local error           = error
    1.17 +local getfenv         = getfenv
    1.18 +local getmetatable    = getmetatable
    1.19 +local ipairs          = ipairs
    1.20 +local load            = load
    1.21 +local loadfile        = loadfile
    1.22 +local loadstring      = loadstring
    1.23 +local next            = next
    1.24 +local pairs           = pairs
    1.25 +local pcall           = pcall
    1.26 +local print           = print
    1.27 +local rawequal        = rawequal
    1.28 +local rawget          = rawget
    1.29 +local rawset          = rawset
    1.30 +local select          = select
    1.31 +local setfenv         = setfenv
    1.32 +local setmetatable    = setmetatable
    1.33 +local tonumber        = tonumber
    1.34 +local tostring        = tostring
    1.35 +local type            = type
    1.36 +local unpack          = unpack
    1.37 +local xpcall          = xpcall
    1.38 +
    1.39 +local coroutine       = coroutine
    1.40 +local io              = io
    1.41 +local math            = math
    1.42 +local os              = os
    1.43 +local string          = string
    1.44 +local table           = table
    1.45 +
    1.46 +local add             = table.insert
    1.47 +
    1.48 +_G[...] = require("mondelefant_native")
    1.49 +module(...)
    1.50 +
    1.51 +
    1.52 +
    1.53 +---------------
    1.54 +-- selectors --
    1.55 +---------------
    1.56 +
    1.57 +selector_metatable = {}
    1.58 +selector_prototype = {}
    1.59 +selector_metatable.__index = selector_prototype
    1.60 +
    1.61 +local function init_selector(self, db_conn)
    1.62 +  self._db_conn = db_conn
    1.63 +  self._mode = "list"
    1.64 +  self._fields = { sep = ", " }
    1.65 +  self._distinct = false
    1.66 +  self._distinct_on = {sep = ", ", expression}
    1.67 +  self._from = { sep = " " }
    1.68 +  self._where = { sep = " AND " }
    1.69 +  self._group_by = { sep = ", " }
    1.70 +  self._having = { sep = " AND " }
    1.71 +  self._combine = { sep = " " }
    1.72 +  self._order_by = { sep = ", " }
    1.73 +  self._limit = nil
    1.74 +  self._offset = nil
    1.75 +  --[[
    1.76 +  self._lock = nil
    1.77 +  self._lock_tables = { sep = ", " }
    1.78 +  --]]
    1.79 +  self._class = nil
    1.80 +  self._attach = nil
    1.81 +  return self
    1.82 +end
    1.83 +
    1.84 +function connection_prototype:new_selector()
    1.85 +  return init_selector(setmetatable({}, selector_metatable), self)
    1.86 +end
    1.87 +
    1.88 +function selector_prototype:get_db_conn()
    1.89 +  return self._db_conn
    1.90 +end
    1.91 +
    1.92 +-- TODO: selector clone?
    1.93 +
    1.94 +function selector_prototype:single_object_mode()
    1.95 +  self._mode = "object"
    1.96 +  return self
    1.97 +end
    1.98 +
    1.99 +function selector_prototype:optional_object_mode()
   1.100 +  self._mode = "opt_object"
   1.101 +  return self
   1.102 +end
   1.103 +
   1.104 +function selector_prototype:empty_list_mode()
   1.105 +  self._mode = "empty_list"
   1.106 +  return self
   1.107 +end
   1.108 +
   1.109 +function selector_prototype:add_distinct_on(expression)
   1.110 +  if self._distinct then
   1.111 +    error("Can not combine DISTINCT with DISTINCT ON.")
   1.112 +  end
   1.113 +  add(self._distinct_on, expression)
   1.114 +  return self
   1.115 +end
   1.116 +
   1.117 +function selector_prototype:set_distinct()
   1.118 +  if #self._distinct_on > 0 then
   1.119 +    error("Can not combine DISTINCT with DISTINCT ON.")
   1.120 +  end
   1.121 +  self._distinct = true
   1.122 +  return self
   1.123 +end
   1.124 +
   1.125 +function selector_prototype:add_from(expression, alias, condition)
   1.126 +  local first = (#self._from == 0)
   1.127 +  if not first then
   1.128 +    if condition then
   1.129 +      add(self._from, "INNER JOIN")
   1.130 +    else
   1.131 +      add(self._from, "CROSS JOIN")
   1.132 +    end
   1.133 +  end
   1.134 +  if getmetatable(expression) == selector_metatable then
   1.135 +    if alias then
   1.136 +      add(self._from, {'($) AS "$"', {expression}, {alias}})
   1.137 +    else
   1.138 +      add(self._from, {'($) AS "subquery"', {expression}})
   1.139 +    end
   1.140 +  else
   1.141 +    if alias then
   1.142 +      add(self._from, {'$ AS "$"', {expression}, {alias}})
   1.143 +    else
   1.144 +      add(self._from, expression)
   1.145 +    end
   1.146 +  end
   1.147 +  if condition then
   1.148 +    if first then
   1.149 +      self:condition(condition)
   1.150 +    else
   1.151 +      add(self._from, "ON")
   1.152 +      add(self._from, condition)
   1.153 +    end
   1.154 +  end
   1.155 +  return self
   1.156 +end
   1.157 +
   1.158 +function selector_prototype:add_where(expression)
   1.159 +  add(self._where, expression)
   1.160 +  return self
   1.161 +end
   1.162 +
   1.163 +function selector_prototype:add_group_by(expression)
   1.164 +  add(self._group_by, expression)
   1.165 +  return self
   1.166 +end
   1.167 +
   1.168 +function selector_prototype:add_having(expression)
   1.169 +  add(self._having, expression)
   1.170 +  return self
   1.171 +end
   1.172 +
   1.173 +function selector_prototype:add_combine(expression)
   1.174 +  add(self._combine, expression)
   1.175 +  return self
   1.176 +end
   1.177 +
   1.178 +function selector_prototype:add_order_by(expression)
   1.179 +  add(self._order_by, expression)
   1.180 +  return self
   1.181 +end
   1.182 +
   1.183 +function selector_prototype:limit(count)
   1.184 +  if type(count) ~= "number" or count % 1 ~= 0 then
   1.185 +    error("LIMIT must be an integer.")
   1.186 +  end
   1.187 +  self._limit = count
   1.188 +  return self
   1.189 +end
   1.190 +
   1.191 +function selector_prototype:offset(count)
   1.192 +  if type(count) ~= "number" or count % 1 ~= 0 then
   1.193 +    error("OFFSET must be an integer.")
   1.194 +  end
   1.195 +  self._offset = count
   1.196 +  return self
   1.197 +end
   1.198 +
   1.199 +function selector_prototype:reset_fields()
   1.200 +  for idx in ipairs(self._fields) do
   1.201 +    self._fields[idx] = nil
   1.202 +  end
   1.203 +  return self
   1.204 +end
   1.205 +
   1.206 +function selector_prototype:add_field(expression, alias, options)
   1.207 +  if alias then
   1.208 +    add(self._fields, {'$ AS "$"', {expression}, {alias}})
   1.209 +  else
   1.210 +    add(self._fields, expression)
   1.211 +  end
   1.212 +  if options then
   1.213 +    for i, option in ipairs(options) do
   1.214 +      if option == "distinct" then
   1.215 +        if alias then
   1.216 +          self:add_distinct_on('"' .. alias .. '"')
   1.217 +        else
   1.218 +          self:add_distinct_on(expression)
   1.219 +        end
   1.220 +      elseif option == "grouped" then
   1.221 +        if alias then
   1.222 +          self:add_group_by('"' .. alias .. '"')
   1.223 +        else
   1.224 +          self:add_group_by(expression)
   1.225 +        end
   1.226 +      else
   1.227 +        error("Unknown option '" .. option .. "' to add_field method.")
   1.228 +      end
   1.229 +    end
   1.230 +  end
   1.231 +  return self
   1.232 +end
   1.233 +
   1.234 +function selector_prototype:join(...)  -- NOTE: alias for add_from
   1.235 +  return self:add_from(...)
   1.236 +end
   1.237 +
   1.238 +function selector_prototype:from(expression, alias, condition)
   1.239 +  if #self._from > 0 then
   1.240 +    error("From-clause already existing (hint: try join).")
   1.241 +  end
   1.242 +  return self:join(expression, alias, condition)
   1.243 +end
   1.244 +
   1.245 +function selector_prototype:left_join(expression, alias, condition)
   1.246 +  local first = (#self._from == 0)
   1.247 +  if not first then
   1.248 +    add(self._from, "LEFT OUTER JOIN")
   1.249 +  end
   1.250 +  if alias then
   1.251 +    add(self._from, {'$ AS "$"', {expression}, {alias}})
   1.252 +  else
   1.253 +    add(self._from, expression)
   1.254 +  end
   1.255 +  if condition then
   1.256 +    if first then
   1.257 +      self:condition(condition)
   1.258 +    else
   1.259 +      add(self._from, "ON")
   1.260 +      add(self._from, condition)
   1.261 +    end
   1.262 +  end
   1.263 +  return self
   1.264 +end
   1.265 +
   1.266 +function selector_prototype:union(expression)
   1.267 +  self:add_combine{"UNION $", {expression}}
   1.268 +  return self
   1.269 +end
   1.270 +
   1.271 +function selector_prototype:union_all(expression)
   1.272 +  self:add_combine{"UNION ALL $", {expression}}
   1.273 +  return self
   1.274 +end
   1.275 +
   1.276 +function selector_prototype:intersect(expression)
   1.277 +  self:add_combine{"INTERSECT $", {expression}}
   1.278 +  return self
   1.279 +end
   1.280 +
   1.281 +function selector_prototype:intersect_all(expression)
   1.282 +  self:add_combine{"INTERSECT ALL $", {expression}}
   1.283 +  return self
   1.284 +end
   1.285 +
   1.286 +function selector_prototype:except(expression)
   1.287 +  self:add_combine{"EXCEPT $", {expression}}
   1.288 +  return self
   1.289 +end
   1.290 +
   1.291 +function selector_prototype:except_all(expression)
   1.292 +  self:add_combine{"EXCEPT ALL $", {expression}}
   1.293 +  return self
   1.294 +end
   1.295 +
   1.296 +function selector_prototype:set_class(class)
   1.297 +  self._class = class
   1.298 +  return self
   1.299 +end
   1.300 +
   1.301 +function selector_prototype:attach(mode, data2, field1, field2, ref1, ref2)
   1.302 +  self._attach = {
   1.303 +    mode = mode,
   1.304 +    data2 = data2,
   1.305 +    field1 = field1,
   1.306 +    field2 = field2,
   1.307 +    ref1 = ref1,
   1.308 +    ref2 = ref2
   1.309 +  }
   1.310 +  return self
   1.311 +end
   1.312 +
   1.313 +-- TODO: many-to-many relations
   1.314 +
   1.315 +function selector_metatable:__tostring()
   1.316 +  local parts = {sep = " "}
   1.317 +  add(parts, "SELECT")
   1.318 +  if self._distinct then
   1.319 +    add(parts, "DISTINCT")
   1.320 +  elseif #self._distinct_on > 0 then
   1.321 +    add(parts, {"DISTINCT ON ($)", self._distinct_on})
   1.322 +  end
   1.323 +  add(parts, {"$", self._fields})
   1.324 +  if #self._from > 0 then
   1.325 +    add(parts, {"FROM $", self._from})
   1.326 +  end
   1.327 +  if #self._mode == "empty_list" then
   1.328 +    add(parts, "WHERE FALSE")
   1.329 +  elseif #self._where > 0 then
   1.330 +    add(parts, {"WHERE $", self._where})
   1.331 +  end
   1.332 +  if #self._group_by > 0 then
   1.333 +    add(parts, {"GROUP BY $", self._group_by})
   1.334 +  end
   1.335 +  if #self._having > 0 then
   1.336 +    add(parts, {"HAVING $", self._having})
   1.337 +  end
   1.338 +  for i, v in ipairs(self._combine) do
   1.339 +    add(parts, v)
   1.340 +  end
   1.341 +  if #self._order_by > 0 then
   1.342 +    add(parts, {"ORDER BY $", self._order_by})
   1.343 +  end
   1.344 +  if self._mode == "empty_list" then
   1.345 +    add(parts, "LIMIT 0")
   1.346 +  elseif self._mode ~= "list" then
   1.347 +    add(parts, "LIMIT 1")
   1.348 +  elseif self._limit then
   1.349 +    add(parts, "LIMIT " .. self._limit)
   1.350 +  end
   1.351 +  if self._offset then
   1.352 +    add(parts, "OFFSET " .. self._offset)
   1.353 +  end
   1.354 +  return self._db_conn:assemble_command{"$", parts}
   1.355 +end
   1.356 +
   1.357 +function selector_prototype:try_exec()
   1.358 +  if self._mode == "empty_list" then
   1.359 +    if self._class then
   1.360 +      return nil, self._class:create_list()
   1.361 +    else
   1.362 +       return nil, self._db_conn:create_list()
   1.363 +    end
   1.364 +  end
   1.365 +  local db_error, db_result = self._db_conn:try_query(self, self._mode)
   1.366 +  if db_error then
   1.367 +    return db_error
   1.368 +  elseif db_result then
   1.369 +    if self._class then set_class(db_result, self._class) end
   1.370 +    if self._attach then
   1.371 +      attach(
   1.372 +        self._attach.mode,
   1.373 +        db_result,
   1.374 +        self._attach.data2,
   1.375 +        self._attach.field1,
   1.376 +        self._attach.field2,
   1.377 +        self._attach.ref1,
   1.378 +        self._attach.ref2
   1.379 +      )
   1.380 +    end
   1.381 +    return nil, db_result
   1.382 +  else
   1.383 +    return nil
   1.384 +  end
   1.385 +end
   1.386 +
   1.387 +function selector_prototype:exec()
   1.388 +  local db_error, result = self:try_exec()
   1.389 +  if db_error then
   1.390 +    db_error:escalate()
   1.391 +  else
   1.392 +    return result
   1.393 +  end
   1.394 +end
   1.395 +
   1.396 +
   1.397 +
   1.398 +-----------------
   1.399 +-- attachments --
   1.400 +-----------------
   1.401 +
   1.402 +local function attach_key(row, fields)
   1.403 +  local t = type(fields)
   1.404 +  if t == "string" then
   1.405 +    return tostring(row[fields])
   1.406 +  elseif t == "table" then
   1.407 +    local r = {}
   1.408 +    for idx, field in ipairs(fields) do
   1.409 +      r[idx] = string.format("%q", row[field])
   1.410 +    end
   1.411 +    return table.concat(r)
   1.412 +  else
   1.413 +    error("Field information for 'mondelefant.attach' is neither a string nor a table.")
   1.414 +  end
   1.415 +end
   1.416 +
   1.417 +function attach(mode, data1, data2, key1, key2, ref1, ref2)
   1.418 +  local many1, many2
   1.419 +  if mode == "11" then
   1.420 +    many1 = false
   1.421 +    many2 = false
   1.422 +  elseif mode == "1m" then
   1.423 +    many1 = false
   1.424 +    many2 = true
   1.425 +  elseif mode == "m1" then
   1.426 +    many1 = true
   1.427 +    many2 = false
   1.428 +  elseif mode == "mm" then
   1.429 +    many1 = true
   1.430 +    many2 = true
   1.431 +  else
   1.432 +    error("Unknown mode specified for 'mondelefant.attach'.")
   1.433 +  end
   1.434 +  local list1, list2
   1.435 +  if data1._type == "object" then
   1.436 +    list1 = { data1 }
   1.437 +  elseif data1._type == "list" then
   1.438 +    list1 = data1
   1.439 +  else
   1.440 +    error("First result data given to 'mondelefant.attach' is invalid.")
   1.441 +  end
   1.442 +  if data2._type == "object" then
   1.443 +    list2 = { data2 }
   1.444 +  elseif data2._type == "list" then
   1.445 +    list2 = data2
   1.446 +  else
   1.447 +    error("Second result data given to 'mondelefant.attach' is invalid.")
   1.448 +  end
   1.449 +  local hash1 = {}
   1.450 +  local hash2 = {}
   1.451 +  if ref2 then
   1.452 +    for i, row in ipairs(list1) do
   1.453 +      local key = attach_key(row, key1)
   1.454 +      local list = hash1[key]
   1.455 +      if not list then list = {}; hash1[key] = list end
   1.456 +      list[#list + 1] = row
   1.457 +    end
   1.458 +  end
   1.459 +  if ref1 then
   1.460 +    for i, row in ipairs(list2) do
   1.461 +      local key = attach_key(row, key2)
   1.462 +      local list = hash2[key]
   1.463 +      if not list then list = {}; hash2[key] = list end
   1.464 +      list[#list + 1] = row
   1.465 +    end
   1.466 +    for i, row in ipairs(list1) do
   1.467 +      local key = attach_key(row, key1)
   1.468 +      local matching_rows = hash2[key]
   1.469 +      if many2 then
   1.470 +        local list = data2._connection:create_list(matching_rows)
   1.471 +        list._class = data2._class
   1.472 +        row._ref[ref1] = list
   1.473 +      elseif matching_rows and #matching_rows == 1 then
   1.474 +        row._ref[ref1] = matching_rows[1]
   1.475 +      else
   1.476 +        row._ref[ref1] = false
   1.477 +      end
   1.478 +    end
   1.479 +  end
   1.480 +  if ref2 then
   1.481 +    for i, row in ipairs(list2) do
   1.482 +      local key = attach_key(row, key2)
   1.483 +      local matching_rows = hash1[key]
   1.484 +      if many1 then
   1.485 +        local list = data1._connection:create_list(matching_rows)
   1.486 +        list._class = data1._class
   1.487 +        row._ref[ref2] = list
   1.488 +      elseif matching_rows and #matching_rows == 1 then
   1.489 +        row._ref[ref2] = matching_rows[1]
   1.490 +      else
   1.491 +        row._ref[ref2] = false
   1.492 +      end
   1.493 +    end
   1.494 +  end
   1.495 +end
   1.496 +
   1.497 +
   1.498 +
   1.499 +------------------
   1.500 +-- model system --
   1.501 +------------------
   1.502 +
   1.503 +class_prototype.primary_key = "id"
   1.504 +
   1.505 +function class_prototype:get_db_conn()
   1.506 +  error(
   1.507 +    "Method mondelefant class(_prototype):get_db_conn() " ..
   1.508 +    "has to be implemented."
   1.509 +  )
   1.510 +end
   1.511 +
   1.512 +function class_prototype:get_qualified_table()
   1.513 +  if not self.table then error "Table unknown." end
   1.514 +  if self.schema then
   1.515 +    return '"' .. self.schema .. '"."' .. self.table .. '"'
   1.516 +  else
   1.517 +    return '"' .. self.table .. '"'
   1.518 +  end
   1.519 +end
   1.520 +
   1.521 +function class_prototype:get_qualified_table_literal()
   1.522 +  if not self.table then error "Table unknown." end
   1.523 +  if self.schema then
   1.524 +    return self.schema .. '.' .. self.table
   1.525 +  else
   1.526 +    return self.table
   1.527 +  end
   1.528 +end
   1.529 +
   1.530 +function class_prototype:get_primary_key_list()
   1.531 +  local primary_key = self.primary_key
   1.532 +  if type(primary_key) == "string" then
   1.533 +    return {primary_key}
   1.534 +  else
   1.535 +    return primary_key
   1.536 +  end
   1.537 +end
   1.538 +
   1.539 +function class_prototype:get_columns()
   1.540 +  if self._columns then
   1.541 +    return self._columns
   1.542 +  end
   1.543 +  local selector = self:get_db_conn():new_selector()
   1.544 +  selector:set_class(self)
   1.545 +  selector:from(self:get_qualified_table())
   1.546 +  selector:add_field("*")
   1.547 +  selector:add_where("FALSE")
   1.548 +  local db_result = selector:exec()
   1.549 +  local connection = db_result._connection
   1.550 +  local columns = {}
   1.551 +  for idx, info in ipairs(db_result._column_info) do
   1.552 +    local key   = info.field_name
   1.553 +    local value = {
   1.554 +      name = key,
   1.555 +      type = connection.type_mappings[info.type]
   1.556 +    }
   1.557 +    columns[key] = value
   1.558 +    table.insert(columns, value)
   1.559 +  end
   1.560 +  self._columns = columns
   1.561 +  return columns
   1.562 +end
   1.563 +
   1.564 +function class_prototype:new_selector(db_conn)
   1.565 +  local selector = (db_conn or self:get_db_conn()):new_selector()
   1.566 +  selector:set_class(self)
   1.567 +  selector:from(self:get_qualified_table())
   1.568 +  selector:add_field(self:get_qualified_table() .. ".*")
   1.569 +  return selector
   1.570 +end
   1.571 +
   1.572 +function class_prototype:create_list()
   1.573 +  local list = self:get_db_conn():create_list()
   1.574 +  list._class = self
   1.575 +  return list
   1.576 +end
   1.577 +
   1.578 +function class_prototype:new()
   1.579 +  local object = self:get_db_conn():create_object()
   1.580 +  object._class = self
   1.581 +  object._new = true
   1.582 +  return object
   1.583 +end
   1.584 +
   1.585 +function class_prototype.object:try_save()
   1.586 +  if not self._class then
   1.587 +    error("Cannot save object: No class information available.")
   1.588 +  end
   1.589 +  local primary_key = self._class:get_primary_key_list()
   1.590 +  local primary_key_sql = { sep = ", " }
   1.591 +  for idx, value in ipairs(primary_key) do
   1.592 +    primary_key_sql[idx] = '"' .. value .. '"'
   1.593 +  end
   1.594 +  if self._new then
   1.595 +    local fields = {sep = ", "}
   1.596 +    local values = {sep = ", "}
   1.597 +    for key, dummy in pairs(self._dirty or {}) do
   1.598 +      add(fields, {'"$"', {key}})
   1.599 +      add(values, {'?', self[key]})
   1.600 +    end
   1.601 +    if compat_returning then  -- compatibility for PostgreSQL 8.1
   1.602 +      local db_error, db_result1, db_result2 = self._connection:try_query(
   1.603 +        {
   1.604 +          'INSERT INTO $ ($) VALUES ($)',
   1.605 +          {self._class:get_qualified_table()},
   1.606 +          fields,
   1.607 +          values,
   1.608 +          primary_key_sql
   1.609 +        },
   1.610 +        "list",
   1.611 +        {
   1.612 +          'SELECT currval(?)',
   1.613 +          self._class.table .. '_id_seq'
   1.614 +        },
   1.615 +        "object"
   1.616 +      )
   1.617 +      if db_error then
   1.618 +        return db_error
   1.619 +      end
   1.620 +      self.id = db_result2.id
   1.621 +    else
   1.622 +      local db_error, db_result = self._connection:try_query(
   1.623 +        {
   1.624 +          'INSERT INTO $ ($) VALUES ($) RETURNING ($)',
   1.625 +          {self._class:get_qualified_table()},
   1.626 +          fields,
   1.627 +          values,
   1.628 +          primary_key_sql
   1.629 +        },
   1.630 +        "object"
   1.631 +      )
   1.632 +      if db_error then
   1.633 +        return db_error
   1.634 +      end
   1.635 +      for idx, value in ipairs(primary_key) do
   1.636 +        self[value] = db_result[value]
   1.637 +      end
   1.638 +    end
   1.639 +    self._new = false
   1.640 +  else
   1.641 +    local command_sets = {sep = ", "}
   1.642 +    for key, dummy in pairs(self._dirty or {}) do
   1.643 +      add(command_sets, {'"$" = ?', {key}, self[key]})
   1.644 +    end
   1.645 +    if #command_sets >= 1 then
   1.646 +      local primary_key_compare = {sep = " AND "}
   1.647 +      for idx, value in ipairs(primary_key) do
   1.648 +        primary_key_compare[idx] = {
   1.649 +          "$ = ?",
   1.650 +          {'"' .. value .. '"'},
   1.651 +          self[value]
   1.652 +        }
   1.653 +      end
   1.654 +      local db_error = self._connection:try_query{
   1.655 +        'UPDATE $ SET $ WHERE $',
   1.656 +        {self._class:get_qualified_table()},
   1.657 +        command_sets,
   1.658 +        primary_key_compare
   1.659 +      }
   1.660 +      if db_error then
   1.661 +        return db_error
   1.662 +      end
   1.663 +    end
   1.664 +  end
   1.665 +  return nil
   1.666 +end
   1.667 +
   1.668 +function class_prototype.object:save()
   1.669 +  local db_error = self:try_save()
   1.670 +  if db_error then
   1.671 +    db_error:escalate()
   1.672 +  end
   1.673 +  return self
   1.674 +end
   1.675 +
   1.676 +function class_prototype.object:try_destroy()
   1.677 +  if not self._class then
   1.678 +    error("Cannot destroy object: No class information available.")
   1.679 +  end
   1.680 +  local primary_key = self._class:get_primary_key_list()
   1.681 +  local primary_key_compare = {sep = " AND "}
   1.682 +  for idx, value in ipairs(primary_key) do
   1.683 +    primary_key_compare[idx] = {
   1.684 +      "$ = ?",
   1.685 +      {'"' .. value .. '"'},
   1.686 +      self[value]
   1.687 +    }
   1.688 +  end
   1.689 +  return self._connection:try_query{
   1.690 +    'DELETE FROM $ WHERE $',
   1.691 +    {self._class:get_qualified_table()},
   1.692 +    primary_key_compare
   1.693 +  }
   1.694 +end
   1.695 +
   1.696 +function class_prototype.object:destroy()
   1.697 +  local db_error = self:try_destroy()
   1.698 +  if db_error then
   1.699 +    db_error:escalate()
   1.700 +  end
   1.701 +  return self
   1.702 +end
   1.703 +
   1.704 +function class_prototype.list:get_reference_selector(
   1.705 +  ref_name, options, ref_alias, back_ref_alias
   1.706 +)
   1.707 +  local ref_info = self._class.references[ref_name]
   1.708 +  if not ref_info then
   1.709 +    error('Reference with name "' .. ref_name .. '" not found.')
   1.710 +  end
   1.711 +  local selector = ref_info.selector_generator(self, options or {})
   1.712 +  local mode = ref_info.mode
   1.713 +  if mode == "mm" or mode == "1m" then
   1.714 +    mode = "m1"
   1.715 +  elseif mode == "m1" then
   1.716 +    mode = "1m"
   1.717 +  end
   1.718 +  local ref_alias = ref_alias
   1.719 +  if ref_alias == false then
   1.720 +    ref_alias = nil
   1.721 +  elseif ref_alias == nil then
   1.722 +    ref_alias = ref_name
   1.723 +  end
   1.724 +  local back_ref_alias
   1.725 +  if back_ref_alias == false then
   1.726 +    back_ref_alias = nil
   1.727 +  elseif back_ref_alias == nil then
   1.728 +    back_ref_alias = ref_info.back_ref
   1.729 +  end
   1.730 +  selector:attach(
   1.731 +    mode,
   1.732 +    self,
   1.733 +    ref_info.that_key,                   ref_info.this_key,
   1.734 +    back_ref_alias or ref_info.back_ref, ref_alias or ref_name
   1.735 +  )
   1.736 +  return selector
   1.737 +end
   1.738 +
   1.739 +function class_prototype.list.load(...)
   1.740 +  return class_prototype.list.get_reference_selector(...):exec()
   1.741 +end
   1.742 +
   1.743 +function class_prototype.object:get_reference_selector(...)
   1.744 +  local list = self._class:create_list()
   1.745 +  list[1] = self
   1.746 +  return list:get_reference_selector(...)
   1.747 +end
   1.748 +
   1.749 +function class_prototype.object.load(...)
   1.750 +  return class_prototype.object.get_reference_selector(...):exec()
   1.751 +end
   1.752 +
   1.753 +
   1.754 +function class_prototype:add_reference(args)
   1.755 +  local selector_generator    = args.selector_generator
   1.756 +  local mode                  = args.mode
   1.757 +  local to                    = args.to
   1.758 +  local this_key              = args.this_key
   1.759 +  local that_key              = args.that_key
   1.760 +  local connected_by_table    = args.connected_by_table  -- TODO: split to table and schema
   1.761 +  local connected_by_this_key = args.connected_by_this_key
   1.762 +  local connected_by_that_key = args.connected_by_that_key
   1.763 +  local ref                   = args.ref
   1.764 +  local back_ref              = args.back_ref
   1.765 +  local default_order         = args.default_order
   1.766 +  local model
   1.767 +  local function get_model()
   1.768 +    if not model then
   1.769 +      if type(to) == "string" then
   1.770 +        model = _G
   1.771 +        for path_element in string.gmatch(to, "[^.]+") do
   1.772 +          model = model[path_element]
   1.773 +        end
   1.774 +      elseif type(to) == "function" then
   1.775 +        model = to()
   1.776 +      else
   1.777 +        model = to
   1.778 +      end
   1.779 +    end
   1.780 +    if not model or model == _G then
   1.781 +      error("Could not get model for reference.")
   1.782 +    end
   1.783 +    return model
   1.784 +  end
   1.785 +  self.references[ref] = {
   1.786 +    mode     = mode,
   1.787 +    this_key = this_key,
   1.788 +    that_key = connected_by_table and "mm_ref_" or that_key,
   1.789 +    ref      = ref,
   1.790 +    back_ref = back_ref,
   1.791 +    selector_generator = selector_generator or function(list, options)
   1.792 +      -- TODO: support tuple keys
   1.793 +      local options = options or {}
   1.794 +      local model = get_model()
   1.795 +      -- TODO: too many records cause PostgreSQL command stack overflow
   1.796 +      local ids = { sep = ", " }
   1.797 +      for i, object in ipairs(list) do
   1.798 +        local id = object[this_key]
   1.799 +        if id ~= nil then
   1.800 +          ids[#ids+1] = {"?", id}
   1.801 +        end
   1.802 +      end
   1.803 +      if #ids == 0 then
   1.804 +        return model:new_selector():empty_list_mode()
   1.805 +      end
   1.806 +      local selector = model:new_selector()
   1.807 +      if connected_by_table then
   1.808 +        selector:join(
   1.809 +          connected_by_table,
   1.810 +          nil,
   1.811 +          {
   1.812 +            '$."$" = $."$"',
   1.813 +            {connected_by_table},
   1.814 +            {connected_by_that_key},
   1.815 +            {model:get_qualified_table()},
   1.816 +            {that_key}
   1.817 +          }
   1.818 +        )
   1.819 +        selector:add_field(
   1.820 +          {
   1.821 +            '$."$"',
   1.822 +            {connected_by_table},
   1.823 +            {connected_by_this_key}
   1.824 +          },
   1.825 +          'mm_ref_'
   1.826 +        )
   1.827 +        selector:add_where{
   1.828 +          '$."$" IN ($)',
   1.829 +          {connected_by_table},
   1.830 +          {connected_by_this_key},
   1.831 +          ids
   1.832 +        }
   1.833 +      else
   1.834 +        selector:add_where{'"$" IN ($)', {that_key}, ids}
   1.835 +      end
   1.836 +      if options.order == nil and default_order then
   1.837 +        selector:add_order_by(default_order)
   1.838 +      elseif options.order then
   1.839 +        selector:add_order_by(options.order)
   1.840 +      end
   1.841 +      return selector
   1.842 +    end
   1.843 +  }
   1.844 +  if mode == "m1" or mode == "11" then
   1.845 +    self.foreign_keys[this_key] = ref
   1.846 +  end
   1.847 +  return self
   1.848 +end