Different model_call return format.

Author: mworrell

src/template_compiler.erl

@@ -1,8 +1,8 @@
 %% @author Marc Worrell <marc@worrell.nl>
-%% @copyright 2016 Marc Worrell
+%% @copyright 2016-2021 Marc Worrell
 %% @doc Main template compiler entry points.
 
-%% Copyright 2016 Marc Worrell
+%% Copyright 2016-2021 Marc Worrell
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -53,6 +53,9 @@
 -type template_key() :: {ContextName::term(), Runtime::atom(), template()}.
 -type render_result() :: binary() | string() | term() | list(render_result()).
 
+-type model_return() :: {ok, {term(), list()}}
+                      | {error, term()}.
+
 -type builtin_tag() :: image
                      | image_url
                      | image_data_url
@@ -77,7 +80,9 @@
     template_file/0,
     template_key/0,
     builtin_tag/0,
-    translation_message/0
+    translation_message/0,
+    render_result/0,
+    model_return/0
 ]).
 
 

src/template_compiler_expr.erl

@@ -137,23 +137,33 @@ compile({apply_filter, Expr, {filter, {identifier, SrcPos, Filter}, FilterArgs}}
                          erl_syntax:atom(FilterName),
                          Args)),
     {Ws2, Ast};
-compile({model, [{identifier, SrcPos, Model} | Path ], OptPayload}, #cs{runtime=Runtime} = CState, Ws) ->
+compile({model, [{identifier, SrcPos, Model} | Path ], OptPayload}, #cs{runtime=Runtime, vars_var=Vars} = CState, Ws) ->
     {Ws1, PathAsts} = value_lookup_asts(Path, CState, Ws, []),
     {Ws2, PayloadAst} = case OptPayload of
         none -> {Ws1, erl_syntax:abstract(undefined)};
         Expr -> compile(Expr, CState, Ws1)
     end,
+    {Ws3, V1} = template_compiler_utils:var(Ws2),
+    {Ws4, V2} = template_compiler_utils:var(Ws3),
     Ast = merl:qquote(
             template_compiler_utils:pos(SrcPos),
-            "_@runtime:model_call(_@model, _@path, _@payload, _@context)",
+            "case _@runtime:model_call(_@model, _@path, _@payload, _@context) of "
+            "  {ok, {_@v1, []}} -> _@v1;"
+            "  {ok, {_@v1, _@v2}} when is_list(_@v2) -> "
+            "       _@runtime:find_nested_value(_@v1, _@v2, _@vars, _@context); "
+            "  {error, _} -> undefined "
+            "end",
             [
                 {model, erl_syntax:atom(binary_to_atom(Model, 'utf8'))},
                 {path, erl_syntax:list(PathAsts)},
                 {payload, PayloadAst},
+                {v1, erl_syntax:variable(V1)},
+                {v2, erl_syntax:variable(V2)},
+                {vars, erl_syntax:variable(Vars)},
                 {context, erl_syntax:variable(CState#cs.context_var)},
                 {runtime, erl_syntax:atom(Runtime)}
             ]),
-    {Ws2, Ast}.
+    {Ws4, Ast}.
 
 
 find_value_lookup([{identifier, SrcPos, <<"now">>}], _CState, Ws) ->

src/template_compiler_runtime.erl

@@ -66,6 +66,7 @@
 -callback get_translations(Text :: binary(), Context :: term()) -> binary() | {trans, [{atom(), binary()}]}.
 -callback lookup_translation({trans, list({atom(), binary()})}, TplVars :: map(), Context :: term()) -> binary().
 
+-callback model_call(Model::atom(), Path::list(), Payload::term(), Context::term()) -> template_compiler:model_return().
 -callback custom_tag(Module::atom(), Args::list(), TplVars::map(), Context::term()) -> template_compiler:render_result().
 -callback builtin_tag(template_compiler:builtin_tag(), term(), Args::list(), TplVars::map(), Context::term()) -> template_compiler:render_result().
 -callback cache_tag(Seconds::integer(), Name::binary(), Args::list(), function(), TplVars::map(), Context::term()) -> template_compiler:render_result().
@@ -289,9 +290,9 @@ lookup_translation({trans, Tr}, TplVars, _Context) when is_map(TplVars) ->
     end.
 
 %% @doc A model call with optional payload. Compiled from m.model.path!payload
--spec model_call(Model::atom(), Path::list(), Payload::term(), Context::term()) -> template_compiler:render_result().
+-spec model_call(Model::atom(), Path::list(), Payload::term(), Context::term()) -> template_compiler:model_return().
 model_call(Model, Path, Payload, _Context) ->
-    io_lib:format("model:~p ~p :: ~p", [ Model, Path, Payload ]).
+    {ok, {io_lib:format("model:~p ~p :: ~p", [ Model, Path, Payload ]), []}}.
 
 %% @doc Render a custom tag (Zotonic scomp) - this can be changed to more complex runtime lookups.
 -spec custom_tag(Tag::atom(), Args::list(), Vars::map(), Context::term()) -> template_compiler:render_result().