412 lines
16 KiB
Haskell
412 lines
16 KiB
Haskell
{-# LANGUAGE FlexibleInstances #-}
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{-# LANGUAGE TupleSections #-}
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{-# OPTIONS_GHC -fno-warn-orphans #-}
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module PostgREST.QueryBuilder (
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addRelations
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, addJoinConditions
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, asCsvF
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, asJson
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, asJsonF
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, asJsonSingleF
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, callProc
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, countAllF
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, countF
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, countNoneF
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, locationF
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, operators
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, pgFmtIdent
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, pgFmtLit
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, requestToQuery
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, selectStarF
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, sourceSubqueryName
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, unquoted
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, wrapQuery
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) where
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import qualified Hasql as H
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import qualified Hasql.Backend as B
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import qualified Hasql.Postgres as P
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import qualified Data.Aeson as JSON
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import PostgREST.RangeQuery (NonnegRange, rangeLimit, rangeOffset)
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import Control.Error (note, fromMaybe, mapMaybe)
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import Control.Monad (join)
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import qualified Data.HashMap.Strict as HM
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import Data.List (find)
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import Data.Monoid ((<>))
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import Data.Text (Text, intercalate, unwords, replace, isInfixOf, toLower, split)
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import qualified Data.Text as T (map, takeWhile)
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import Data.String.Conversions (cs)
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import Control.Applicative (empty, (<|>))
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import Data.Tree (Tree(..))
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import qualified Data.Vector as V
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import PostgREST.Types
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import qualified Data.Map as M
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import Text.Regex.TDFA ((=~))
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import qualified Data.ByteString.Char8 as BS
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import Data.Scientific ( FPFormat (..)
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, formatScientific
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, isInteger
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)
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import Prelude hiding (unwords)
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type PStmt = H.Stmt P.Postgres
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instance Monoid PStmt where
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mappend (B.Stmt query params prep) (B.Stmt query' params' prep') =
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B.Stmt (query <> query') (params <> params') (prep && prep')
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mempty = B.Stmt "" empty True
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type StatementT = PStmt -> PStmt
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addRelations :: Schema -> [Relation] -> Maybe ReadRequest -> ReadRequest -> Either Text ReadRequest
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addRelations schema allRelations parentNode node@(Node n@(query, (table, _)) forest) =
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case parentNode of
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Nothing -> Node (query, (table, Nothing)) <$> updatedForest
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(Just (Node (_, (parentTable, _)) _)) -> Node <$> (addRel n <$> rel) <*> updatedForest
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where
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rel = note ("no relation between " <> table <> " and " <> parentTable)
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$ findRelation schema table parentTable
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<|> findRelation schema parentTable table
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addRel :: (ReadQuery, (NodeName, Maybe Relation)) -> Relation -> (ReadQuery, (NodeName, Maybe Relation))
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addRel (q, (t, _)) r = (q, (t, Just r))
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where
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updatedForest = mapM (addRelations schema allRelations (Just node)) forest
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findRelation s t1 t2 =
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find (\r -> s == (tableSchema . relTable) r && t1 == (tableName . relTable) r && t2 == (tableName . relFTable) r) allRelations
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addJoinConditions :: Schema -> ReadRequest -> Either Text ReadRequest
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addJoinConditions schema (Node (query, (n, r)) forest) =
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case r of
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Nothing -> Node (updatedQuery, (n,r)) <$> updatedForest -- this is the root node
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Just rel@(Relation{relType=Child}) -> Node (addCond updatedQuery (getJoinConditions rel),(n,r)) <$> updatedForest
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Just (Relation{relType=Parent}) -> Node (updatedQuery, (n,r)) <$> updatedForest
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Just rel@(Relation{relType=Many, relLTable=(Just linkTable)}) ->
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Node (qq, (n, r)) <$> updatedForest
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where
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q = addCond updatedQuery (getJoinConditions rel)
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qq = q{from=tableName linkTable : from q}
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_ -> Left "unknown relation"
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where
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-- add parentTable and parentJoinConditions to the query
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updatedQuery = foldr (flip addCond) (query{from = parentTables ++ from query}) parentJoinConditions
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where
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parentJoinConditions = map (getJoinConditions . snd) parents
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parentTables = map fst parents
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parents = mapMaybe (getParents . rootLabel) forest
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getParents (_, (tbl, Just rel@(Relation{relType=Parent}))) = Just (tbl, rel)
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getParents _ = Nothing
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updatedForest = mapM (addJoinConditions schema) forest
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addCond q con = q{flt_=con ++ flt_ q}
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asCsvF :: SqlFragment
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asCsvF = asCsvHeaderF <> " || '\n' || " <> asCsvBodyF
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where
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asCsvHeaderF =
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"(SELECT string_agg(a.k, ',')" <>
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" FROM (" <>
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" SELECT json_object_keys(r)::TEXT as k" <>
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" FROM ( " <>
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" SELECT row_to_json(hh) as r from " <> sourceSubqueryName <> " as hh limit 1" <>
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" ) s" <>
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" ) a" <>
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")"
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asCsvBodyF = "coalesce(string_agg(substring(t::text, 2, length(t::text) - 2), '\n'), '')"
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asJson :: StatementT
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asJson s = s {
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B.stmtTemplate =
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"array_to_json(coalesce(array_agg(row_to_json(t)), '{}'))::character varying from ("
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<> B.stmtTemplate s <> ") t" }
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asJsonF :: SqlFragment
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asJsonF = "array_to_json(array_agg(row_to_json(t)))::character varying"
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asJsonSingleF :: SqlFragment --TODO! unsafe when the query actually returns multiple rows, used only on inserting and returning single element
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asJsonSingleF = "string_agg(row_to_json(t)::text, ',')::character varying "
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callProc :: QualifiedIdentifier -> JSON.Object -> PStmt
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callProc qi params = do
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let args = intercalate "," $ map assignment (HM.toList params)
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B.Stmt ("select * from " <> fromQi qi <> "(" <> args <> ")") empty True
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where
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assignment (n,v) = pgFmtIdent n <> ":=" <> insertableValue v
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countAllF :: SqlFragment
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countAllF = "(SELECT pg_catalog.count(1) FROM (SELECT * FROM " <> sourceSubqueryName <> ") a )"
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countF :: SqlFragment
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countF = "pg_catalog.count(t)"
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countNoneF :: SqlFragment
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countNoneF = "null"
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locationF :: [Text] -> SqlFragment
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locationF pKeys =
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"(" <>
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" WITH s AS (SELECT row_to_json(ss) as r from " <> sourceSubqueryName <> " as ss limit 1)" <>
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" SELECT string_agg(json_data.key || '=' || coalesce( 'eq.' || json_data.value, 'is.null'), '&')" <>
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" FROM s, json_each_text(s.r) AS json_data" <>
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(
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if null pKeys
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then ""
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else " WHERE json_data.key IN ('" <> intercalate "','" pKeys <> "')"
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) <>
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")"
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operators :: [(Text, SqlFragment)]
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operators = [
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("eq", "="),
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("gte", ">="), -- has to be before gt (parsers)
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("gt", ">"),
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("lte", "<="), -- has to be before lt (parsers)
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("lt", "<"),
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("neq", "<>"),
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("like", "like"),
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("ilike", "ilike"),
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("in", "in"),
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("notin", "not in"),
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("isnot", "is not"), -- has to be before is (parsers)
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("is", "is"),
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("@@", "@@"),
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("@>", "@>"),
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("<@", "<@")
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]
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pgFmtIdent :: SqlFragment -> SqlFragment
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pgFmtIdent x =
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let escaped = replace "\"" "\"\"" (trimNullChars $ cs x) in
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if (cs escaped :: BS.ByteString) =~ danger
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then "\"" <> escaped <> "\""
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else escaped
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where danger = "^$|^[^a-z_]|[^a-z_0-9]" :: BS.ByteString
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pgFmtLit :: SqlFragment -> SqlFragment
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pgFmtLit x =
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let trimmed = trimNullChars x
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escaped = "'" <> replace "'" "''" trimmed <> "'"
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slashed = replace "\\" "\\\\" escaped in
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if "\\\\" `isInfixOf` escaped
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then "E" <> slashed
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else slashed
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requestToQuery :: Schema -> DbRequest -> SqlQuery
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requestToQuery _ (DbMutate (Insert _ (PayloadParseError _))) = undefined
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requestToQuery _ (DbMutate (Update _ (PayloadParseError _) _)) = undefined
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requestToQuery schema (DbRead (Node (Select colSelects tbls conditions ord, (mainTbl, _)) forest)) =
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query
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where
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-- TODO! the folloing helper functions are just to remove the "schema" part when the table is "source" which is the name
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-- of our WITH query part
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tblSchema tbl = if tbl == sourceSubqueryName then "" else schema
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qi = QualifiedIdentifier (tblSchema mainTbl) mainTbl
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toQi t = QualifiedIdentifier (tblSchema t) t
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query = unwords [
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("WITH " <> intercalate ", " withs) `emptyOnNull` withs,
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"SELECT ", intercalate ", " (map (pgFmtSelectItem qi) colSelects ++ selects),
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"FROM ", intercalate ", " (map (fromQi . toQi) tbls),
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("WHERE " <> intercalate " AND " ( map (pgFmtCondition qi ) conditions )) `emptyOnNull` conditions,
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orderF (fromMaybe [] ord)
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]
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(withs, selects) = foldr getQueryParts ([],[]) forest
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getQueryParts :: Tree ReadNode -> ([SqlFragment], [SqlFragment]) -> ([SqlFragment], [SqlFragment])
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getQueryParts (Node n@(_, (table, Just (Relation {relType=Child}))) forst) (w,s) = (w,sel:s)
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where
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sel = "("
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<> "SELECT array_to_json(array_agg(row_to_json("<>table<>"))) "
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<> "FROM (" <> subquery <> ") " <> table
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<> ") AS " <> table
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where subquery = requestToQuery schema (DbRead (Node n forst))
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getQueryParts (Node n@(_, (table, Just (Relation {relType=Parent}))) forst) (w,s) = (wit:w,sel:s)
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where
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sel = "row_to_json(" <> table <> ".*) AS "<>table --TODO must be singular
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wit = table <> " AS ( " <> subquery <> " )"
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where subquery = requestToQuery schema (DbRead (Node n forst))
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getQueryParts (Node n@(_, (table, Just (Relation {relType=Many}))) forst) (w,s) = (w,sel:s)
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where
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sel = "("
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<> "SELECT array_to_json(array_agg(row_to_json("<>table<>"))) "
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<> "FROM (" <> subquery <> ") " <> table
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<> ") AS " <> table
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where subquery = requestToQuery schema (DbRead (Node n forst))
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--the following is just to remove the warning
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--getQueryParts is not total but requestToQuery is called only after addJoinConditions which ensures the only
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--posible relations are Child Parent Many
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getQueryParts (Node (_,(_,Nothing)) _) _ = undefined
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requestToQuery schema (DbMutate (Insert mainTbl (PayloadJSON (UniformObjects rows)))) =
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let qi = QualifiedIdentifier schema mainTbl
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cols = map pgFmtIdent $ fromMaybe [] (HM.keys <$> (rows V.!? 0))
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colsString = intercalate ", " cols in
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unwords [
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"INSERT INTO ", fromQi qi,
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" (" <> colsString <> ")" <>
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" SELECT " <> colsString <>
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" FROM json_populate_recordset(null::" , fromQi qi, ", ?)",
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" RETURNING " <> fromQi qi <> ".*"
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]
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requestToQuery schema (DbMutate (Update mainTbl (PayloadJSON (UniformObjects rows)) conditions)) =
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case rows V.!? 0 of
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Just obj ->
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let assignments = map
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(\(k,v) -> pgFmtIdent k <> "=" <> insertableValue v) $ HM.toList obj in
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unwords [
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"UPDATE ", fromQi qi,
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" SET " <> intercalate "," assignments <> " ",
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("WHERE " <> intercalate " AND " ( map (pgFmtCondition qi ) conditions )) `emptyOnNull` conditions,
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"RETURNING " <> fromQi qi <> ".*"
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]
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Nothing -> undefined
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where
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qi = QualifiedIdentifier schema mainTbl
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requestToQuery schema (DbMutate (Delete mainTbl conditions)) =
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query
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where
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qi = QualifiedIdentifier schema mainTbl
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query = unwords [
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"DELETE FROM ", fromQi qi,
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("WHERE " <> intercalate " AND " ( map (pgFmtCondition qi ) conditions )) `emptyOnNull` conditions,
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"RETURNING " <> fromQi qi <> ".*"
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]
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selectStarF :: SqlFragment
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selectStarF = "SELECT * FROM " <> sourceSubqueryName
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sourceSubqueryName :: SqlFragment
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sourceSubqueryName = "pg_source"
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unquoted :: JSON.Value -> Text
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unquoted (JSON.String t) = t
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unquoted (JSON.Number n) =
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cs $ formatScientific Fixed (if isInteger n then Just 0 else Nothing) n
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unquoted (JSON.Bool b) = cs . show $ b
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unquoted v = cs $ JSON.encode v
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wrapQuery :: SqlQuery -> [Text] -> Text -> Maybe NonnegRange -> SqlQuery
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wrapQuery source selectColumns returnSelect range =
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withSourceF source <>
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" SELECT " <>
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intercalate ", " selectColumns <>
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" " <>
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fromF returnSelect ( limitF range )
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-- private functions
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fromQi :: QualifiedIdentifier -> SqlFragment
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fromQi t = (if s == "" then "" else pgFmtIdent s <> ".") <> pgFmtIdent n
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where
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n = qiName t
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s = qiSchema t
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getJoinConditions :: Relation -> [Filter]
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getJoinConditions (Relation t cols ft fcs typ lt lc1 lc2) =
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case typ of
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Child -> zipWith (toFilter tN ftN) cols fcs
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Parent -> zipWith (toFilter tN ftN) cols fcs
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Many -> zipWith (toFilter tN ltN) cols (fromMaybe [] lc1) ++ zipWith (toFilter ftN ltN) fcs (fromMaybe [] lc2)
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where
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s = tableSchema t
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tN = tableName t
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ftN = tableName ft
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ltN = fromMaybe "" (tableName <$> lt)
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toFilter :: Text -> Text -> Column -> Column -> Filter
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toFilter tb ftb c fc = Filter (colName c, Nothing) "=" (VForeignKey (QualifiedIdentifier s tb) (ForeignKey fc{colTable=(colTable fc){tableName=ftb}}))
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emptyOnNull :: Text -> [a] -> Text
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emptyOnNull val x = if null x then "" else val
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orderF :: [OrderTerm] -> SqlFragment
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orderF ts =
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if null ts
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then ""
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else "ORDER BY " <> clause
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where
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clause = intercalate "," (map queryTerm ts)
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queryTerm :: OrderTerm -> Text
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queryTerm t = " "
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<> cs (pgFmtIdent $ otTerm t) <> " "
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<> (cs.show) (otDirection t) <> " "
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<> maybe "" (cs.show) (otNullOrder t) <> " "
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insertableValue :: JSON.Value -> SqlFragment
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insertableValue JSON.Null = "null"
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insertableValue v = (<> "::unknown") . pgFmtLit $ unquoted v
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whiteList :: Text -> SqlFragment
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whiteList val = fromMaybe
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(cs (pgFmtLit val) <> "::unknown ")
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(find ((==) . toLower $ val) ["null","true","false"])
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pgFmtColumn :: QualifiedIdentifier -> Text -> SqlFragment
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pgFmtColumn table "*" = fromQi table <> ".*"
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pgFmtColumn table c = fromQi table <> "." <> pgFmtIdent c
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pgFmtField :: QualifiedIdentifier -> Field -> SqlFragment
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pgFmtField table (c, jp) = pgFmtColumn table c <> pgFmtJsonPath jp
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pgFmtSelectItem :: QualifiedIdentifier -> SelectItem -> SqlFragment
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pgFmtSelectItem table (f@(_, jp), Nothing) = pgFmtField table f <> pgFmtAsJsonPath jp
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pgFmtSelectItem table (f@(_, jp), Just cast ) = "CAST (" <> pgFmtField table f <> " AS " <> cast <> " )" <> pgFmtAsJsonPath jp
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pgFmtCondition :: QualifiedIdentifier -> Filter -> SqlFragment
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pgFmtCondition table (Filter (col,jp) ops val) =
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notOp <> " " <> sqlCol <> " " <> pgFmtOperator opCode <> " " <>
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if opCode `elem` ["is","isnot"] then whiteList (getInner val) else sqlValue
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where
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headPredicate:rest = split (=='.') ops
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hasNot caseTrue caseFalse = if headPredicate == "not" then caseTrue else caseFalse
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opCode = hasNot (head rest) headPredicate
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notOp = hasNot headPredicate ""
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sqlCol = case val of
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VText _ -> pgFmtColumn table col <> pgFmtJsonPath jp
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VForeignKey qi _ -> pgFmtColumn qi col
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sqlValue = valToStr val
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getInner v = case v of
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VText s -> s
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_ -> ""
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valToStr v = case v of
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VText s -> pgFmtValue opCode s
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VForeignKey (QualifiedIdentifier s _) (ForeignKey Column{colTable=Table{tableName=ft}, colName=fc}) -> pgFmtColumn qi fc
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where qi = QualifiedIdentifier (if ft == sourceSubqueryName then "" else s) ft
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_ -> ""
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pgFmtValue :: Text -> Text -> SqlFragment
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pgFmtValue opCode val =
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case opCode of
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"like" -> unknownLiteral $ T.map star val
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"ilike" -> unknownLiteral $ T.map star val
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"in" -> "(" <> intercalate ", " (map unknownLiteral $ split (==',') val) <> ") "
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"notin" -> "(" <> intercalate ", " (map unknownLiteral $ split (==',') val) <> ") "
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"@@" -> "to_tsquery(" <> unknownLiteral val <> ") "
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_ -> unknownLiteral val
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where
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star c = if c == '*' then '%' else c
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unknownLiteral = (<> "::unknown ") . pgFmtLit
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pgFmtOperator :: Text -> SqlFragment
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pgFmtOperator opCode = fromMaybe "=" $ M.lookup opCode operatorsMap
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where
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operatorsMap = M.fromList operators
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pgFmtJsonPath :: Maybe JsonPath -> SqlFragment
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pgFmtJsonPath (Just [x]) = "->>" <> pgFmtLit x
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pgFmtJsonPath (Just (x:xs)) = "->" <> pgFmtLit x <> pgFmtJsonPath ( Just xs )
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pgFmtJsonPath _ = ""
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pgFmtAsJsonPath :: Maybe JsonPath -> SqlFragment
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pgFmtAsJsonPath Nothing = ""
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pgFmtAsJsonPath (Just xx) = " AS " <> last xx
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trimNullChars :: Text -> Text
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trimNullChars = T.takeWhile (/= '\x0')
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withSourceF :: SqlFragment -> SqlFragment
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withSourceF s = "WITH " <> sourceSubqueryName <> " AS (" <> s <>")"
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fromF :: SqlFragment -> SqlFragment -> SqlFragment
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fromF sel limit = "FROM (" <> sel <> " " <> limit <> ") t"
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limitF :: Maybe NonnegRange -> SqlFragment
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limitF r = "LIMIT " <> limit <> " OFFSET " <> offset
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where
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limit = maybe "ALL" (cs . show) $ join $ rangeLimit <$> r
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offset = cs . show $ fromMaybe 0 $ rangeOffset <$> r
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