Do not hide a field with a connection

Closes tarantool#170.

Author: Totktonada

graphql/convert_schema/schema.lua

@@ -221,6 +221,39 @@ local function add_connection_arguments(state)
     end)
 end
 
+--- Check there are no connections named as uppermost fields of a schema and
+--- there are no connections with the same name.
+local function check_connection_names(schema, collection)
+    assert(collection.name ~= nil)
+
+    local connection_names = {}
+    local field_names = {}
+
+    for _, field in ipairs(schema.fields) do
+        local name = field.name
+        assert(name ~= nil)
+        assert(field_names[name] == nil)
+        field_names[name] = true
+    end
+
+    for _, connection in ipairs(collection.connections) do
+        local name = connection.name
+        assert(name ~= nil)
+        if connection_names[name] ~= nil then
+            local err = ('[collection "%s"] two connections are named "%s"')
+                :format(collection.name, name)
+            error(err)
+        end
+        if field_names[name] ~= nil then
+            local err = ('[collection "%s"] the connection "%s" is named ' ..
+                'as a schema field'):format(collection.name, name)
+            error(err)
+        end
+        connection_names[name] = true
+        field_names[name] = true
+    end
+end
+
 function schema.convert(state, cfg)
     -- collection type is always record, so always non-null; we can lazily
     -- evaluate non-null type from nullable type, but not vice versa, so we
@@ -275,6 +308,8 @@ function schema.convert(state, cfg)
             'top-level schema must have record avro type, got ' ..
             tostring(schema.type))
 
+        check_connection_names(schema, collection)
+
         -- fill schema with expanded references
         local e_schema = avro_helpers.expand_references(schema)
         cfg.e_schemas[collection.schema_name] = e_schema

test/extra/connections_do_not_hide_fields.test.lua

@@ -0,0 +1,144 @@
+#!/usr/bin/env tarantool
+
+-- https://github.com/tarantool/graphql/issues/170
+
+local fio = require('fio')
+local json = require('json')
+local tap = require('tap')
+
+-- require in-repo version of graphql/ sources despite current working directory
+package.path = fio.abspath(debug.getinfo(1).source:match("@?(.*/)")
+    :gsub('/./', '/'):gsub('/+$', '')) .. '/../../?.lua' .. ';' ..
+    package.path
+
+local graphql = require('graphql')
+local utils = require('graphql.utils')
+local test_utils = require('test.test_utils')
+
+local test = tap.test('connections do not hide fields')
+
+box.cfg{wal_mode='none'}
+test:plan(3)
+
+local schemas = json.decode([[{
+    "foo": {
+        "name": "foo",
+        "type": "record",
+        "fields": [
+            { "name": "foo_id", "type": "string" },
+            { "name": "bar", "type": "string" }
+        ]
+    },
+    "bar": {
+        "name": "bar",
+        "type": "record",
+        "fields": [
+            { "name": "bar_id", "type": "string" }
+        ]
+    }
+}]])
+
+local collections_1 = json.decode([[{
+    "foo": {
+        "schema_name": "foo",
+        "connections": [
+            {
+                "type": "1:1",
+                "name": "bar",
+                "destination_collection": "bar",
+                "parts": [
+                   {
+                       "source_field": "bar",
+                       "destination_field": "bar_id"
+                   }
+                ],
+                "index_name": "bar_id"
+            }
+        ]
+    },
+    "bar": {
+        "schema_name": "bar",
+        "connections": []
+    }
+}]])
+
+local collections_2 = table.deepcopy(collections_1)
+collections_2.foo.connections[1].type = '1:N'
+
+local collections_3 = table.deepcopy(collections_1)
+collections_3.foo.connections[1].name = 'bar_c'
+table.insert(collections_3.foo.connections, collections_3.foo.connections[1])
+
+local service_fields = {
+    foo = {},
+    bar = {},
+}
+
+local indexes = {
+    foo = {
+        foo_id = {
+            service_fields = {},
+            fields = {'foo_id'},
+            index_type = 'tree',
+            unique = true,
+            primary = true,
+        },
+    },
+    bar = {
+        bar_id = {
+            service_fields = {},
+            fields = {'bar_id'},
+            index_type = 'tree',
+            unique = true,
+            primary = true,
+        },
+    },
+}
+
+local cfg_1 = utils.merge_tables({
+    schemas = schemas,
+    collections = collections_1,
+    service_fields = service_fields,
+    indexes = indexes,
+    accessor = 'space',
+}, test_utils.test_conf_graphql_opts())
+
+local cfg_2 = table.deepcopy(cfg_1)
+cfg_2.collections = collections_2
+
+local cfg_3 = table.deepcopy(cfg_1)
+cfg_3.collections = collections_3
+
+-- schema field name clash with 1:1 connection name
+-- ------------------------------------------------
+
+local exp_err = '[collection "foo"] the connection "bar" is named ' ..
+    'as a schema field'
+
+local ok, err = pcall(graphql.new, cfg_1)
+
+test:is_deeply({ok, utils.strip_error(err)}, {false, exp_err},
+    'do not hide fields for 1:1 connections')
+
+-- schema field name clash with 1:N connection name
+-- ------------------------------------------------
+
+local exp_err = '[collection "foo"] the connection "bar" is named ' ..
+    'as a schema field'
+
+local ok, err = pcall(graphql.new, cfg_2)
+
+test:is_deeply({ok, utils.strip_error(err)}, {false, exp_err},
+    'do not hide fields for 1:N connections')
+
+-- connections names clash
+-- -----------------------
+
+local exp_err = '[collection "foo"] two connections are named "bar_c"'
+
+local ok, err = pcall(graphql.new, cfg_3)
+
+test:is_deeply({ok, utils.strip_error(err)}, {false, exp_err},
+    'do not hide a connection with a connection')
+
+os.exit(test:check() == true and 0 or 1)