util.datamapper: Improve handling of schemas with non-obvious "type"

The JSON Schema specification says that schemas are objects or booleans,
and that the 'type' property is optional and can be an array.

This module previously allowed bare type names as schemas and did not
really handle booleans.

It now handles missing 'type' properties and boolean 'true' as a schema.
Objects and arrays are guessed based on the presence of 'properties' or
'items' field.

1 files changed, 27 insertions, 10 deletions

diff --git a/util/datamapper.lua b/util/datamapper.lua
index 25c4c986..2378314c 100644
--- a/util/datamapper.lua
+++ b/util/datamapper.lua
@@ -1,3 +1,5 @@
+-- This file is generated from teal-src/util/datamapper.lua
+
 local st = require("util.stanza");
 local pointer = require("util.jsonpointer");
 
@@ -29,15 +31,28 @@ end
 local value_goes = {}
 
 local function resolve_schema(schema, root)
-	if type(schema) == "table" and schema["$ref"] and schema["$ref"]:sub(1, 1) == "#" then
-		local referenced = pointer.resolve(root, schema["$ref"]:sub(2));
-		if referenced ~= nil then
-			return referenced
+	if type(schema) == "table" then
+		if schema["$ref"] and schema["$ref"]:sub(1, 1) == "#" then
+			return pointer.resolve(root, schema["$ref"]:sub(2))
 		end
 	end
 	return schema
 end
 
+local function guess_schema_type(schema)
+	local schema_types = schema.type
+	if type(schema_types) == "string" then
+		return schema_types
+	elseif schema_types ~= nil then
+		error("schema has unsupported 'type' property")
+	elseif schema.properties then
+		return "object"
+	elseif schema.items then
+		return "array"
+	end
+	return "string"
+end
+
 local function unpack_propschema(propschema, propname, current_ns)
 
 	local proptype = "string"
@@ -49,9 +64,9 @@ local function unpack_propschema(propschema, propname, current_ns)
 	local enums
 
 	if type(propschema) == "table" then
-		proptype = propschema.type
+		proptype = guess_schema_type(propschema);
 	elseif type(propschema) == "string" then
-		proptype = propschema
+		error("schema as string is not supported: " .. propschema .. " {" .. current_ns .. "}" .. propname)
 	end
 
 	if proptype == "object" or proptype == "array" then
@@ -209,9 +224,10 @@ function parse_array(schema, s, root)
 end
 
 local function parse(schema, s)
-	if schema.type == "object" then
+	local s_type = guess_schema_type(schema)
+	if s_type == "object" then
 		return parse_object(schema, s, schema)
-	elseif schema.type == "array" then
+	elseif s_type == "array" then
 		return parse_array(schema, s, schema)
 	else
 		error("top-level scalars unsupported")
@@ -306,7 +322,8 @@ function unparse(schema, t, current_name, current_ns, ctx, root)
 
 	local out = ctx or st.stanza(current_name, {xmlns = current_ns})
 
-	if schema.type == "object" then
+	local s_type = guess_schema_type(schema)
+	if s_type == "object" then
 
 		for prop, propschema in pairs(schema.properties) do
 			propschema = resolve_schema(propschema, root)
@@ -319,7 +336,7 @@ function unparse(schema, t, current_name, current_ns, ctx, root)
 		end
 		return out
 
-	elseif schema.type == "array" then
+	elseif s_type == "array" then
 		local itemschema = resolve_schema(schema.items, root)
 		local proptype, value_where, name, namespace, prefix, single_attribute = unpack_propschema(itemschema, current_name, current_ns)
 		for _, item in ipairs(t) do