mssql: basic support for geography and geometry types

GitOrigin-RevId: 97bbf0e8d53b00c9f4365b145adb19bdcd769ceb

CHANGELOG.md

@@ -1,6 +1,12 @@
 # Hasura GraphQL Engine Changelog
 
 ## Next release
+
+### Bug fixes and improvements
+
+- server/mssql: fix runtime errors when selecting geography/geometry columns
+
+## v1.4.0-alpha.2
 ### MSSQL support
 
 It's now possible to add a MSSQL server as a source. For now, only read-only queries and subscriptions are supported.

server/src-lib/Hasura/Backends/MSSQL/FromIr.hs

@@ -587,14 +587,20 @@ fromAnnColumnField ::
   -> ReaderT EntityAlias FromIr Expression
 fromAnnColumnField _stringifyNumbers annColumnField = do
   fieldName <- fromPGCol pgCol
-  if asText || True -- TODO: FIXME:
-               -- TODO: Does MSSQL support bignums? Probably, but needs researching.
-               {-(IR.isScalarColumnWhere PG.isBigNum typ && stringifyNumbers == StringifyNumbers)-}
-     then pure (ToStringExpression (ColumnExpression fieldName))
+  -- TODO: Handle stringifying large numbers
+  {-(IR.isScalarColumnWhere PG.isBigNum typ && stringifyNumbers == StringifyNumbers)-}
+
+  -- for geometry and geography values, the automatic json encoding on sql
+  -- server would fail. So we need to convert it to a format the json encoding
+  -- handles. Ideally we want this representation to be GeoJSON but sql server
+  -- doesn't have any functions to convert to GeoJSON format. So we return it in
+  -- WKT format
+  if typ == (IR.ColumnScalar GeometryType) || typ == (IR.ColumnScalar GeographyType)
+     then pure $ MethodExpression (ColumnExpression fieldName) "STAsText" []
      else pure (ColumnExpression fieldName)
   where
-    IR.AnnColumnField { _acfInfo = IR.ColumnInfo{pgiColumn=pgCol,pgiType=_typ}
-                      , _acfAsText = asText :: Bool
+    IR.AnnColumnField { _acfInfo = IR.ColumnInfo{pgiColumn=pgCol,pgiType=typ}
+                      , _acfAsText = _asText :: Bool
                       , _acfOp = _ :: Maybe (IR.ColumnOp 'MSSQL) -- TODO: What's this?
                       } = annColumnField
 

server/src-lib/Hasura/Backends/MSSQL/Meta.hs

@@ -3,8 +3,7 @@
 -- |
 
 module Hasura.Backends.MSSQL.Meta
-  ( MetadataError(..)
-  , loadDBMetadata
+  ( loadDBMetadata
   ) where
 
 import           Hasura.Prelude
@@ -31,10 +30,6 @@ import           Hasura.SQL.Backend
 --------------------------------------------------------------------------------
 -- Loader
 
-data MetadataError
-  = UnknownScalarType Text
-  deriving (Show)
-
 loadDBMetadata :: Connection -> IO (DBTablesMetadata 'MSSQL)
 loadDBMetadata conn = do
   let sql = $(Q.sqlFromFile "src-rsr/mssql_table_metadata.sql")
@@ -179,6 +174,8 @@ parseScalarType = \case
   "varbinary"        -> VarbinaryType
   "bit"              -> BitType
   "uniqueidentifier" -> GuidType
+  "geography"        -> GeographyType
+  "geometry"         -> GeometryType
   t                  -> UnknownType t
 
 

server/src-lib/Hasura/Backends/MSSQL/ToQuery.hs

@@ -93,6 +93,10 @@ fromExpression =
       "(" <+> fromExpression x <+> ") != (" <+> fromExpression y <+> ")"
     ToStringExpression e -> "CONCAT(" <+> fromExpression e <+> ", '')"
     SelectExpression s -> "(" <+> IndentPrinter 1 (fromSelect s) <+> ")"
+    MethodExpression field method args ->
+      fromExpression field <+> "." <+>
+      fromString (T.unpack method) <+>
+      "(" <+> (SeqPrinter $ map fromExpression args) <+> ")"
     OpExpression op x y ->
       "(" <+>
       fromExpression x <+>

server/src-lib/Hasura/Backends/MSSQL/Types/Internal.hs

@@ -157,6 +157,8 @@ data Expression
     -- behave like it knows your field is JSON and not double-encode
     -- it.
   | ToStringExpression Expression
+  -- expression.text(e1, e2, ..)
+  | MethodExpression !Expression !Text ![Expression]
   | JsonValueExpression Expression JsonPath
     -- ^ This is for getting actual atomic values out of a JSON
     -- string.
@@ -266,6 +268,8 @@ data ScalarType
   | TinyintType
   | BitType
   | GuidType
+  | GeographyType
+  | GeometryType
   | UnknownType !Text
 
 scalarTypeDBName :: ScalarType -> Text
@@ -291,6 +295,8 @@ scalarTypeDBName = \case
   TinyintType   -> "tinyint"
   BitType       -> "bit"
   GuidType      -> "uniqueidentifier"
+  GeographyType -> "geography"
+  GeometryType  -> "geometry"
   -- the input form for types that aren't explicitly supported is a string
   UnknownType t -> t
 
@@ -317,6 +323,11 @@ parseScalarValue scalarType jValue = case scalarType of
   TinyintType   -> ODBC.IntValue <$> parseJValue jValue
   BitType       -> ODBC.ByteValue <$> parseJValue jValue
   GuidType      -> ODBC.TextValue <$> parseJValue jValue
+
+  -- TODO: We'll need to wrap this with geography::STGeomFromText
+  GeographyType -> ODBC.TextValue <$> parseJValue jValue
+  GeometryType  -> ODBC.TextValue <$> parseJValue jValue
+
   -- the input format for types that aren't explicitly supported is a string
   UnknownType _ -> ODBC.TextValue <$> parseJValue jValue
   where