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%% @doc Process directives in order to validate or modify the given document. |
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%% |
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%% GraphQL has directives that allow attaching additional information to the schema, objects, |
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%% fields, and more. We decided to use directives to check if the user is allowed to execute |
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%% commands and if commands require loaded modules and services. |
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%% |
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%% The behavior consists of two callbacks. One handles field directives, and the second one |
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%% takes object directives. Callbacks can modify the document AST. |
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-module(mongoose_graphql_directive). |
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-export([process_directives/2]). |
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-include_lib("graphql/src/graphql_schema.hrl"). |
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-include_lib("graphql/src/graphql_internal.hrl"). |
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-include_lib("graphql/include/graphql.hrl"). |
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-import(mongoose_graphql_directive_helper, [name/1, op_name/1]). |
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-type document() :: #document{}. |
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-type ctx() :: #{atom() => term()}. |
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-type parent() :: term(). |
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-type process_set_result() :: #{parent := parent(), set := [selection_set()]}. |
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-type process_result() :: #{parent := parent(), schema := selection_set()}. |
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-type directive() :: graphql:directive(). |
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-export_type([ctx/0]). |
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%% Can modify field or throw an graphql error to stop document execution. |
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-callback handle_directive(Dir :: directive(), Field :: schema_field(), Ctx :: map()) -> |
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schema_field(). |
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%% Can modify object and ctx which is later passed to the field directives handler. |
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-callback handle_object_directive(Dir :: directive(), |
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Object :: schema_object(), |
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Ctx :: ctx()) -> |
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{schema_object(), ctx()}. |
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dir_handlers() -> |
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#{<<"use">> => mongoose_graphql_directive_use, |
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<<"protected">> => mongoose_graphql_directive_protected}. |
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%% @doc Traverse given document and process schema directives. The directive handlers can modify |
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%% the AST to impact the result or raise a graphql exception. |
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-spec process_directives(ctx(), document()) -> document(). |
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process_directives(Ctx, #document{definitions = Definitions}) -> |
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#{operation_name := OpName} = Ctx, |
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F = fun(#op{schema = RootObject, selection_set = Set} = Op) -> |
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{RootObject2, Ctx2} = handle_object_directives(RootObject, Ctx), |
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Ctx3 = |
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Ctx2#{parent => RootObject2, |
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definitions => Definitions, |
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path => [op_name(OpName)]}, |
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#{set := ResSet, parent := RootObject3} = process_selection_set(Set, Ctx3), |
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Op#op{schema = RootObject3, selection_set = ResSet} |
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end, |
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Definitions2 = lists:map(fun(D) -> if_req_operation(D, OpName, F) end, Definitions), |
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#document{definitions = Definitions2}. |
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%% Internal |
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-spec process_selection_set([selection_set()], ctx()) -> process_set_result(). |
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process_selection_set(Set, #{parent := InParent} = Ctx) -> |
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Fun = fun(S, #{set := AccSet, parent := AccParent}) -> |
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Ctx2 = Ctx#{parent := AccParent}, |
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#{schema := Schema, parent := Parent} = process_selection(S, Ctx2), |
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#{set => [Schema | AccSet], parent => Parent} |
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end, |
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lists:foldl(Fun, #{set => [], parent => InParent}, Set). |
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%% Process object field's directives. Return modified parent object and field. |
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-spec process_selection(selection_set(), ctx()) -> process_result(). |
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%% Process generic fields e.g. `{ categoryA { commandA } }` |
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process_selection(F = #field{id = Id, |
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selection_set = Set, |
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args = FieldArgs, |
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schema = Schema}, |
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Ctx) -> |
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case Schema of |
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#schema_field{ty = FieldType, directives = Directives} -> |
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Ctx2 = append_path(Ctx, name(Id)), |
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%% Process field type (object) directives |
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{FieldType2, FieldTypeCtx} = handle_object_directives(unwrap_type(FieldType), Ctx2), |
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%% Process field directives |
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ObjField = |
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handle_directives(Directives, |
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get_object_field(Id, Ctx2), |
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set_field_args(FieldArgs, Ctx2)), |
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%% Process field type fields |
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#{set := ResSet, parent := FieldType3} = |
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process_selection_set(Set, set_parent_object(FieldType2, FieldTypeCtx)), |
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FieldType4 = wrap_new_type(FieldType, FieldType3), |
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#{parent => update_object_field(Id, ObjField, Ctx2), |
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schema => |
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F#field{selection_set = ResSet, schema = Schema#schema_field{ty = FieldType4}}}; |
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_ -> |
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% Schema is not a `schema_field()` when a field is an introspection field |
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#{parent => maps:get(parent, Ctx), schema => F} |
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end; |
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%% Process inline fragments e.g. `{ category {commandA { ... on Domain { domain }}}}` |
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process_selection(F = #frag{selection_set = Set, schema = ObjectType}, Ctx) -> |
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% FIXME think if frag is able to have annotations? |
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{ObjectType2, ObjectCtx} = handle_object_directives(ObjectType, Ctx), |
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#{set := ResSet, parent := ObjectType3} = |
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process_selection_set(Set, set_parent_object(ObjectType2, ObjectCtx)), |
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#{parent => maps:get(parent, Ctx), % Return unmodified parent object |
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schema => F#frag{selection_set = ResSet, schema = ObjectType3}}; |
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%% Process fragments e.g. |
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%% ``` |
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%% fragment DomainParts on Domain { domain enabled } |
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%% query { category {commandA { ...DomainParts }}} |
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%% ``` |
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process_selection(F = #frag_spread{id = Id}, Ctx) -> |
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Res = process_selection(get_fragment(Id, Ctx), Ctx), |
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Res#{schema := F}. |
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-spec handle_object_directives(schema_object(), ctx()) -> {schema_object(), ctx()}. |
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handle_object_directives(Object, Ctx) -> |
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Fun = fun(D, {Obj, ObjCtx}) -> handle_object_directive(D, Obj, ObjCtx) end, |
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lists:foldl(Fun, {Object, Ctx#{field_args => []}}, get_directives(Object)). |
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-spec get_directives(schema_object()) -> [directive()]. |
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get_directives(#interface_type{directives = Directives}) -> |
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Directives; |
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get_directives(#object_type{directives = Directives}) -> |
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Directives; |
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get_directives(#union_type{directives = Directives}) -> |
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Directives; |
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get_directives(_) -> |
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[]. |
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-spec handle_object_directive(directive(), object_type(), ctx()) -> |
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{object_type(), ctx()}. |
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handle_object_directive(#directive{id = {name, _, Name}} = D, Field, Ctx) -> |
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handle_object_directive(D#directive{id = Name}, Field, Ctx); |
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handle_object_directive(#directive{id = Name} = D, Field, Ctx) -> |
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Module = maps:get(Name, dir_handlers()), |
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Module:handle_object_directive(D, Field, Ctx). |
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-spec handle_directives([directive()], schema_field(), ctx()) -> schema_field(). |
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handle_directives(Directives, Field, Ctx) -> |
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Fun = fun(D, FieldSchema) -> handle_directive(D, FieldSchema, Ctx) end, |
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lists:foldl(Fun, Field, Directives). |
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-spec handle_directive(directive(), schema_field(), ctx()) -> schema_field(). |
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handle_directive(#directive{id = {name, _, Name}} = D, Field, Ctx) -> |
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handle_directive(D#directive{id = Name}, Field, Ctx); |
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handle_directive(#directive{id = Name} = D, Field, Ctx) -> |
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Module = maps:get(Name, dir_handlers()), |
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Module:handle_directive(D, Field, Ctx). |
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-spec get_fragment(graphql:name(), ctx()) -> frag(). |
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get_fragment(Id, #{definitions := Definitions}) -> |
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Name = name(Id), |
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Fun = fun (#frag{id = FId}) -> |
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name(FId) =:= Name; |
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(_) -> |
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false |
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end, |
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hd(lists:filter(Fun, Definitions)). |
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if_req_operation(#op{id = 'ROOT'} = Op, undefined, Fun) -> |
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Fun(Op); |
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if_req_operation(#op{id = {name, _, Name}} = Op, Name, Fun) -> |
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Fun(Op); |
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if_req_operation(Op, _, _) -> |
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:-( |
Op. |
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field_args_to_map(FieldArgs, Params) -> |
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maps:from_list([prepare_arg(ArgName, Type, Params) || {ArgName, Type} <- FieldArgs]). |
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prepare_arg(ArgName, #{value := #var{id = Name}}, Vars) -> |
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{ArgName, maps:get(name(Name), Vars, null)}; |
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prepare_arg(ArgName, #{value := Val}, _) -> |
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{ArgName, Val}. |
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%% GraphQL type helpers |
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unwrap_type({non_null, {list, T}}) -> |
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T; |
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unwrap_type({non_null, T}) -> |
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T; |
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unwrap_type({list, T}) -> |
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T; |
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unwrap_type(T) -> |
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T. |
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wrap_new_type({non_null, {list, _}}, T) -> |
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{non_null, {list, T}}; |
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wrap_new_type({list, _}, T) -> |
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{list, T}; |
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wrap_new_type({non_null, _}, T) -> |
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{non_null, T}; |
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wrap_new_type(_, T) -> |
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T. |
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update_wrapped_type({non_null, {list, T}}, Fun) -> |
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{non_null, {list, Fun(T)}}; |
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update_wrapped_type({non_null, T}, Fun) -> |
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{non_null, Fun(T)}; |
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update_wrapped_type({list, T}, Fun) -> |
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{list, Fun(T)}; |
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update_wrapped_type(T, Fun) -> |
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Fun(T). |
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%% Context helpers |
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append_path(#{path := Path} = Ctx, FieldName) -> |
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Ctx#{path => [FieldName | Path]}. |
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set_field_args(FieldArgs, #{params := Params} = Ctx) -> |
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Ctx#{field_args => field_args_to_map(FieldArgs, Params)}. |
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set_parent_object(Parent, Ctx) -> |
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Ctx#{parent => Parent}. |
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get_object_field(Id, #{parent := Parent}) -> |
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Fields = |
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case unwrap_type(Parent) of |
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#object_type{fields = Fs} -> |
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Fs; |
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#interface_type{fields = Fs} -> |
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Fs |
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end, |
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maps:get(name(Id), Fields). |
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update_object_field(Id, ObjField, #{parent := ParentType}) -> |
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Fun = fun (#object_type{} = Obj) -> |
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Fields = maps:put(name(Id), ObjField, Obj#object_type.fields), |
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Obj#object_type{fields = Fields}; |
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(#interface_type{} = Int) -> |
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Fields = maps:put(name(Id), ObjField, Int#interface_type.fields), |
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Int#interface_type{fields = Fields} |
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end, |
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update_wrapped_type(ParentType, Fun). |