Add creation of avro-schema from query with

Maps

Close #198

Author: SudoBobo

graphql/convert_schema/types.lua

@@ -448,10 +448,16 @@ function types.convert(state, avro_schema, opts)
             'got %s (avro_schema %s)'):format(type(avro_schema.values),
             json.encode(avro_schema)))
 
-        -- validate avro schema format inside 'values'
-        types.convert(state, avro_schema.values, {context = context})
+        local converted_values = types.convert(state, avro_schema.values,
+            {context = context})
+
+        local true_values_type = converted_values
+        while true_values_type.__type == 'NonNull' do
+            true_values_type = true_values_type.ofType
+        end
+        local map_name = true_values_type.name .. "_Map"
 
-        local res = core_types.map
+        local res = core_types.map({values = converted_values, name = map_name })
         return avro_t == 'map' and core_types.nonNull(res) or res
     elseif avro_t == 'union' then
         return union.convert(avro_schema, {

graphql/convert_schema/union.lua

@@ -38,6 +38,9 @@ local function box_type(type_to_box, box_field_name, opts)
     -- for the argument type to avoid 'Encountered multiple types' error. See
     -- also the comment in @{types.box_collection_type}.
     local box_name = (gql_true_type.name or gql_true_type.__type) .. '_box'
+    if (gql_true_type.__type == "Scalar" and gql_true_type.subtype == 'Map') then
+        box_name = 'Map_box'
+    end
     if gen_argument then
         box_name = helpers.full_name(box_name, context)
     else

graphql/core/types.lua

@@ -191,17 +191,24 @@ function types.union(config)
   return instance
 end
 
-types.map = types.scalar({
-  name = 'Map',
-  description = 'Map is a dictionary with string keys and values of ' ..
-    'arbitrary but same among all values type',
-  serialize = function(value) return value end,
-  parseValue = function(value) return value end,
-  parseLiteral = function(node)
-    error('Literal parsing is implemented in util.coerceValue; ' ..
-      'we should not go here')
-  end,
-})
+function types.map(config)
+    local instance = {
+        __type = 'Scalar',
+        subtype = 'Map',
+        name = config.name,
+        description = 'Map is a dictionary with string keys and values of ' ..
+            'arbitrary but same among all values type',
+        serialize = function(value) return value end,
+        parseValue = function(value) return value end,
+        parseLiteral = function(node)
+            error('Literal parsing is implemented in util.coerceValue; ' ..
+                'we should not go here')
+        end,
+        values = config.values,
+    }
+
+    return instance
+end
 
 function types.inputObject(config)
   assert(type(config.name) == 'string', 'type name must be provided as a string')

graphql/query_to_avro.lua

@@ -16,6 +16,7 @@ local query_to_avro = {}
 
 -- forward declaration
 local object_to_avro
+local map_to_avro
 
 local gql_scalar_to_avro_index = {
     String = "string",
@@ -29,7 +30,9 @@ local gql_scalar_to_avro_index = {
 
 local function gql_scalar_to_avro(fieldType)
     assert(fieldType.__type == "Scalar", "GraphQL scalar field expected")
-    assert(fieldType.name ~= "Map", "Map type is not supported")
+    if (fieldType.subtype == "Map") then
+        return map_to_avro(fieldType)
+    end
     local result = gql_scalar_to_avro_index[fieldType.name]
     assert(result ~= nil, "Unexpected scalar type: " .. fieldType.name)
     return result
@@ -85,6 +88,15 @@ local function gql_type_to_avro(fieldType, subSelections, context)
     return result
 end
 
+--- The function converts a GraphQL Map type to avro-schema map type.
+map_to_avro = function(mapType)
+    assert(mapType.values ~= nil, "GraphQL Map type must have 'values' field")
+    return  {
+        type = "map",
+        values =  gql_type_to_avro(mapType.values),
+    }
+end
+
 --- The function converts a single Object field to avro format.
 local function field_to_avro(object_type, fields, context)
     local firstField = fields[1]