feat: add spread embeds

src/PostgREST/Error.hs

@@ -72,6 +72,7 @@ instance PgrstError ApiRequestError where
   status ParseRequestError{}     = HTTP.status400
   status PutRangeNotAllowedError = HTTP.status400
   status QueryParamError{}       = HTTP.status400
+  status SpreadNotToOne{}        = HTTP.status400
   status UnacceptableSchema{}    = HTTP.status406
   status UnsupportedMethod{}     = HTTP.status405
   status LimitNoOrderError       = HTTP.status400
@@ -159,6 +160,12 @@ instance JSON.ToJSON ApiRequestError where
     "details" .= JSON.Null,
     "hint"    .= JSON.Null]
 
+  toJSON (SpreadNotToOne origin target) = JSON.object [
+    "code"    .= ApiRequestErrorCode19,
+    "message" .= ("A spread operation on '" <> target <> "' is not possible" :: Text),
+    "details" .= ("'" <> origin <> "' and '" <> target <> "' do not form a many-to-one or one-to-one relationship" :: Text),
+    "hint"    .= JSON.Null]
+
   toJSON (NoRelBetween parent child schema) = JSON.object [
     "code"    .= SchemaCacheErrorCode00,
     "message" .= ("Could not find a relationship between '" <> parent <> "' and '" <> child <> "' in the schema cache" :: Text),
@@ -471,6 +478,7 @@ data ErrorCode
   | ApiRequestErrorCode16
   | ApiRequestErrorCode17
   | ApiRequestErrorCode18
+  | ApiRequestErrorCode19
   -- Schema Cache errors
   | SchemaCacheErrorCode00
   | SchemaCacheErrorCode01
@@ -513,6 +521,7 @@ buildErrorCode code = "PGRST" <> case code of
   ApiRequestErrorCode16  -> "116"
   ApiRequestErrorCode17  -> "117"
   ApiRequestErrorCode18  -> "118"
+  ApiRequestErrorCode19  -> "119"
 
   SchemaCacheErrorCode00 -> "200"
   SchemaCacheErrorCode01 -> "201"