WIP: Preliminary patch for update/delete mutations

Author: Totktonada

graphql/accessor_general.lua

@@ -16,6 +16,7 @@ if rex == nil then
     rex, is_pcre2 = utils.optional_require('rex_pcre'), false
 end
 local utils = require('graphql.utils')
+local avro_helpers = require('graphql.avro_helpers')
 
 local check = utils.check
 
@@ -1483,10 +1484,43 @@ function accessor_general.new(opts, funcs)
             extra_args = function(self, collection_name)
                 local collection = self.collections[collection_name]
                 local schema_name = collection.schema_name
-                local schema = table.copy(self.schemas[schema_name])
-                schema.name = collection_name .. '_insert'
+
+                local schema_insert = table.copy(self.schemas[schema_name])
+                schema_insert.name = collection_name .. '_insert'
+
+                -- XXX: opts.multi
+                local schema_update = {
+                    name = collection_name .. '_update',
+                    type = 'record',
+                    fields = {},
+                }
+                for _, field in ipairs(self.schemas[schema_name].fields) do
+                    local field = table.copy(field)
+                    field.type = avro_helpers.make_avro_type_nullable(
+                        field.type)
+                    table.insert(schema_update.fields, field)
+                end
+
+                -- XXX: opts.multi
+                local schema_delete = 'boolean'
+
                 return {
-                    {name = 'insert', type = schema}
+                    {name = 'insert', type = schema_insert},
+                    {name = 'update', type = schema_update},
+                    {name = 'delete', type = schema_delete},
+                }, {
+                    insert = {
+                        add_to_mutations_only = true,
+                        add_to_top_fields_only = true,
+                    },
+                    update = {
+                        add_to_mutations_only = true,
+                        add_to_top_fields_only = false,
+                    },
+                    delete = {
+                        add_to_mutations_only = true,
+                        add_to_top_fields_only = false,
+                    },
                 }
             end,
         }

graphql/avro_helpers.lua

@@ -0,0 +1,74 @@
+--- The module us collection of helpers to simplify avro-schema related tasks.
+
+local json = require('json')
+
+local avro_helpers = {}
+
+--- The function converts avro type to the corresponding nullable type in
+--- place and returns the result.
+---
+--- We make changes in place in case of table input (`avro`) because of
+--- performance reasons, but we returns the result because an input (`avro`)
+--- can be a string. Strings in Lua are immutable.
+---
+--- In the current tarantool/avro-schema implementation we simply add '*' to
+--- the end of a type name or, in case of union, add 'null' branch.
+---
+--- If the type is already nullable the function leaves it as is if
+--- `opts.raise_on_nullable` is false or omitted. If `opts.raise_on_nullable`
+--- is true the function will raise an error.
+---
+--- @tparam table avro avro schema node to be converted to nullable one
+---
+--- @tparam[opt] table opts the following options:
+---
+--- * `raise_on_nullable` (boolean) raise an error on nullable type
+---
+--- @result `result` (string or table) nullable avro type
+function avro_helpers.make_avro_type_nullable(avro, opts)
+    assert(avro ~= nil, "avro must not be nil")
+    local opts = opts or {}
+    assert(type(opts) == 'table',
+        'opts must be nil or a table, got ' .. type(opts))
+    local raise_on_nullable = opts.raise_on_nullable or false
+    assert(type(raise_on_nullable) == 'boolean',
+        'opts.raise_on_nullable must be nil or a boolean, got ' ..
+        type(raise_on_nullable))
+
+    local value_type = type(avro)
+
+    if value_type == "string" then
+        local is_nullable = avro:endswith("*")
+        if raise_on_nullable and is_nullable then
+            error('expected non-null type, got the nullable one: ' ..
+                json.encode(avro))
+        end
+        return is_nullable and avro or (avro .. '*')
+    elseif value_type == 'table' and #avro > 0 then -- union
+        local is_nullable = false
+        for _, branch in ipairs(avro) do
+            if branch == 'null' then
+                is_nullable = true
+                break
+            end
+        end
+        if raise_on_nullable and is_nullable then
+            error('expected non-null type, got the nullable one: ' ..
+                json.encode(avro))
+        end
+        -- We add 'nil' branch to the end because here we don't know whether
+        -- the following things matter for a caller:
+        -- * a default value (it must have the type of the first branch);
+        -- * {,un,x}flatten data layout.
+        if not is_nullable then
+            table.insert(avro, 'null')
+        end
+        return avro
+    elseif value_type == 'table' and #avro == 0 then
+        return avro_helpers.make_avro_type_nullable(avro.type, opts)
+    end
+
+    error("avro should be a string or a table, got " .. value_type)
+end
+
+return avro_helpers

graphql/query_to_avro.lua

@@ -5,10 +5,10 @@
 --- * The best way to use this module is to just call `avro_schema` method on
 ---   compiled query object.
 
-local json = require('json')
 local path = "graphql.core"
 local introspection = require(path .. '.introspection')
 local query_util = require(path .. '.query_util')
+local avro_helpers = require('graphql.avro_helpers')
 
 -- module functions
 local query_to_avro = {}
@@ -25,6 +25,7 @@ local gql_scalar_to_avro_index = {
     Float = "double",
     Boolean = "boolean"
 }
+
 local function gql_scalar_to_avro(fieldType)
     assert(fieldType.__type == "Scalar", "GraphQL scalar field expected")
     assert(fieldType.name ~= "Map", "Map type is not supported")
@@ -33,53 +34,6 @@ local function gql_scalar_to_avro(fieldType)
     return result
 end
 
---- The function converts avro type to the corresponding nullable type in
---- place and returns the result.
----
---- We make changes in place in case of table input (`avro`) because of
---- performance reasons, but we returns the result because an input (`avro`)
---- can be a string. Strings in Lua are immutable.
----
---- In the current tarantool/avro-schema implementation we simply add '*' to
---- the end of a type name.
----
---- If the type is already nullable the function leaves it as if
---- `opts.raise_on_nullable` is false or omitted. If `opts.raise_on_nullable`
---- is true the function will raise an error.
----
---- @tparam table avro avro schema node to be converted to nullable one
----
---- @tparam[opt] table opts the following options:
----
---- * `raise_on_nullable` (boolean) raise an error on nullable type
----
---- @result `result` (string or table) nullable avro type
-local function make_avro_type_nullable(avro, opts)
-    assert(avro ~= nil, "avro must not be nil")
-    local opts = opts or {}
-    assert(type(opts) == 'table',
-        'opts must be nil or a table, got ' .. type(opts))
-    local raise_on_nullable = opts.raise_on_nullable or false
-    assert(type(raise_on_nullable) == 'boolean',
-        'opts.raise_on_nullable must be nil or a boolean, got ' ..
-        type(raise_on_nullable))
-
-    local value_type = type(avro)
-
-    if value_type == "string" then
-        local is_nullable = avro:endswith("*")
-        if raise_on_nullable and is_nullable then
-            error('expected non-null type, got the nullable one: ' ..
-                json.encode(avro))
-        end
-        return is_nullable and avro or (avro .. '*')
-    elseif value_type == "table" then
-        return make_avro_type_nullable(avro.type, opts)
-    end
-
-    error("avro should be a string or a table, got " .. value_type)
-end
-
 --- Convert GraphQL type to avro-schema with selecting fields.
 ---
 --- @tparam table fieldType GraphQL type
@@ -123,7 +77,9 @@ local function gql_type_to_avro(fieldType, subSelections, context)
     end
 
     if not isNonNull then
-        result = make_avro_type_nullable(result, {raise_on_nullable = true})
+        result = avro_helpers.make_avro_type_nullable(result, {
+            raise_on_nullable = true,
+        })
     end
     return result
 end

graphql/tarantool_graphql.lua

@@ -1248,16 +1248,26 @@ local function create_root_collection(state)
         root_types[what] = nullable(gql_type(state, root_schema,
             root_collection, nil))
 
-    end
-
-    -- add extra arguments to top-level fields (collections)
-    for collection_name, field in pairs(root_types['Mutation'].fields) do
-        -- Prevent exposing an argument into the query schema subtree (it is
-        -- needed because we use a booking table for arguments).
-        field.arguments = table.copy(field.arguments)
-
-        for name, arg in pairs(state.extra_arguments[collection_name]) do
-            field.arguments[name] = arg
+        -- add extra arguments to top-level fields (collections)
+        for collection_name, field in pairs(root_types[what].fields) do
+            -- Prevent exposing an argument inserted, say, into the mutation schema
+            -- subtree to the query subtree (it is needed because we use a booking
+            -- table for arguments).
+            field.arguments = table.copy(field.arguments)
+
+            local extra_args = state.extra_arguments[collection_name]
+            local extra_args_meta = state.extra_arguments_meta[collection_name]
+
+            for arg_name, arg in pairs(extra_args) do
+                local meta = extra_args_meta[arg_name]
+                check(meta, 'meta', 'table')
+                -- note: we handle add_to_top_fields_only == false case in
+                -- add_connection_arguments
+                if meta.add_to_top_fields_only and what == 'Mutation' or
+                        not meta.add_to_mutations_only then
+                    field.arguments[arg_name] = arg
+                end
+            end
         end
     end
 
@@ -1343,6 +1353,8 @@ local function add_connection_arguments(state)
             }
         end
     end)
+
+    -- XXX: handle add_to_top_fields_only == false case of extra_arguments
 end
 
 local function parse_cfg(cfg)
@@ -1362,6 +1374,7 @@ local function parse_cfg(cfg)
     -- argument. We capture extra_arguments[collection_name] into the resolve
     -- function and sure it exists and will not be changed.
     state.extra_arguments = utils.gen_booking_table({})
+    state.extra_arguments_meta = {}
 
     -- map from avro-schema names to graphql types
     state.definitions = {}
@@ -1415,12 +1428,16 @@ local function parse_cfg(cfg)
             {skip_compound = true})
         local list_args = convert_record_fields_to_args(
             accessor:list_args(collection_name))
-        local extra_args = convert_record_fields_to_args(
-            accessor:extra_args(collection_name), {dont_skip = true})
+        local extra_args_avro, extra_args_meta = accessor:extra_args(
+            collection_name)
+        check(extra_args_meta, 'extra_args_meta', 'table')
+        local extra_args = convert_record_fields_to_args(extra_args_avro,
+            {dont_skip = true})
 
         state.object_arguments[collection_name] = object_args
         state.list_arguments[collection_name] = list_args
         state.extra_arguments[collection_name] = extra_args
+        state.extra_arguments_meta[collection_name] = extra_args_meta
     end
 
     add_connection_arguments(state)
@@ -1683,7 +1700,14 @@ end
 ---                 }
 ---             end,
 ---             extra_args = function(self, collection_name)
----                 return ...
+---                 ...
+---                 local args_meta = {
+---                     arg_name = {
+---                         add_to_mutations_only = true / false,
+---                         add_to_top_fields_only = true / false,
+---                     }
+---                 }
+---                 return schemas_list, args_meta
 ---             end
 ---         }
 ---     }),