refactor: Split up Types.hs and logically organize modules (#1793)

src/PostgREST/Request/Preferences.hs

@@ -0,0 +1,54 @@
+module PostgREST.Request.Preferences where
+
+import GHC.Show
+import Protolude
+
+
+data PreferResolution
+  = MergeDuplicates
+  | IgnoreDuplicates
+
+instance Show PreferResolution where
+  show MergeDuplicates  = "resolution=merge-duplicates"
+  show IgnoreDuplicates = "resolution=ignore-duplicates"
+
+-- | How to return the mutated data. From https://tools.ietf.org/html/rfc7240#section-4.2
+data PreferRepresentation
+  = Full        -- ^ Return the body plus the Location header(in case of POST).
+  | HeadersOnly -- ^ Return the Location header(in case of POST). This needs a SELECT privilege on the pk.
+  | None        -- ^ Return nothing from the mutated data.
+  deriving Eq
+
+instance Show PreferRepresentation where
+  show Full        = "return=representation"
+  show None        = "return=minimal"
+  show HeadersOnly = mempty
+
+data PreferParameters
+  = SingleObject    -- ^ Pass all parameters as a single json object to a stored procedure
+  | MultipleObjects -- ^ Pass an array of json objects as params to a stored procedure
+  deriving Eq
+
+instance Show PreferParameters where
+  show SingleObject    = "params=single-object"
+  show MultipleObjects = "params=multiple-objects"
+
+data PreferCount
+  = ExactCount     -- ^ exact count(slower)
+  | PlannedCount   -- ^ PostgreSQL query planner rows count guess. Done by using EXPLAIN {query}.
+  | EstimatedCount -- ^ use the query planner rows if the count is superior to max-rows, otherwise get the exact count.
+  deriving Eq
+
+instance Show PreferCount where
+  show ExactCount     = "count=exact"
+  show PlannedCount   = "count=planned"
+  show EstimatedCount = "count=estimated"
+
+data PreferTransaction
+  = Commit   -- Commit transaction - the default.
+  | Rollback -- Rollback transaction after sending the response - does not persist changes, e.g. for running tests.
+  deriving Eq
+
+instance Show PreferTransaction where
+  show Commit   = "tx=commit"
+  show Rollback = "tx=rollback"