% vim: sw=4 ts=4 et ft=erlang % Nitrogen Web Framework for Erlang % Copyright (c) 2008-2010 Rusty Klophaus % See MIT-LICENSE for licensing information. -module (wf_render_elements). -include("wf.hrl"). -export ([ render_elements/1, render_and_trap_actions/1, temp_id/0, normalize_id/1, recurse_body/2, cache_rendered/3 ]). -spec render_and_trap_actions(Elements :: body() | fun()) -> {ok, Html :: binary(), Actions :: binary()}. render_and_trap_actions(Elements) -> ?WF_IF(not(wf:in_request()), wf_context:init_context(undefined)), OldActionQueue = wf_context:action_queue(), wf_context:clear_action_queue(), {ok, Html} = case is_function(Elements) of true -> render_elements(Elements()); false -> render_elements(Elements) end, {ok, JS} = wf_render_actions:render_action_queue(), wf_context:action_queue(OldActionQueue), {ok, Html, wf:to_unicode_binary(JS)}. cache_rendered(Key, TTL, Fun) -> {ok, Html, Actions} = wf:cache(Key, TTL, fun() -> wf:render_isolated(Fun) end), wf:wire(Actions), Html. % Render elements and return the HTML that was produced. % Puts any new actions into the current context. -spec render_elements(Elements :: body()) -> {ok, html()}. render_elements(Elements) -> %wf_utils:write_debug(render_elements, Elements), {ok, inner_render_elements(Elements)}. -spec inner_render_elements(E :: body()) -> html(). inner_render_elements(undefined) -> []; inner_render_elements([]) -> []; inner_render_elements(E) when is_binary(E); is_integer(E) -> E; inner_render_elements([E|T]) -> [inner_render_elements(E) | inner_render_elements(T)]; inner_render_elements(E) when is_tuple(E) -> %wf_utils:write_debug(render_element, E), render_element(E); inner_render_elements(mobile_script) -> mobile_script; inner_render_elements(script) -> script; inner_render_elements(Atom) when is_atom(Atom) -> wf:to_binary(Atom); inner_render_elements(Unknown) -> throw({unanticipated_case_in_render_elements, Unknown}). % This is a Nitrogen element, so render it. -spec render_element(nitrogen_element()) -> html(). render_element(Element) when is_tuple(Element) -> % Get the element's backing module... Base = wf_utils:get_elementbase(Element), verify_and_render(Base, Element). verify_and_render(Base = #elementbase{is_element=is_element}, Element) -> inner_render_element(Base, Element); verify_and_render(_, Element) -> wf:error("Attempting to render an element that is not an element: ~p",[Element]), wf:f("Unrenderable Element: 
~p
",[Element]). %throw({not_an_element, Element}). -spec inner_render_element(#elementbase{}, nitrogen_element()) -> html(). inner_render_element(#elementbase{show_if=false}, _Element) -> []; inner_render_element(Base = #elementbase{show_if=true}, Element) -> Module = Base#elementbase.module, case code:ensure_loaded(Module) of {module, Module} -> prepare_and_render_or_transform(Module, Base, Element); Response -> ElementName = element(1, Element), exit({failed_to_ensure_module_loaded, [{element, ElementName}, {'response_from code:ensure_loaded', Response}, {module, Module}, {record, Element}]}) end. -spec prepare_and_render_or_transform(Module :: atom(), #elementbase{}, nitrogen_element()) -> html(). prepare_and_render_or_transform(Module, Base, Element) -> case erlang:function_exported(Module,transform_element,1) of true -> %% Module:transform_element is a special shortcut mechanism %% of rendering elements without any of the overhead of %% the pre-rendering that goes on with each element. This %% should be used for custom elements that are simply %% defined in terms of other Nitrogen elements. _Html = call_element_render(transform_element, Module, Element); false -> prepare_and_render(Module, Base, Element) end. -spec prepare_and_render(Module :: atom(), #elementbase{}, nitrogen_element()) -> html(). prepare_and_render(Module, Base, Element) -> % TODO: Revisit generating an ID for each element, instead % generating the ID only if an element has actions. % Otherwise, if an element needs an ID for something % special (like how the #button element needs an anchor to % wire the postback to and for validation stuff), let the % element_render function take care of that itself. % % This change will provide a handful of performance % improvements: % + Removes having to call temp_id() for every element % + Removes having to call normalize_id() possibly twice % for each element % + Lightens the page size since every element won't have % an unnecessary 'tempABCXYZ' class. % Get the anchor, ID, and Class, or create a new ones if not defined... Anchor = extract_anchor(Base), ID = extract_id(Base, Anchor), Class = extract_class(Base, Anchor, ID), % Update the base element with the new id and class... Base1 = Base#elementbase{id=ID, anchor=Anchor, class=Class}, Element1 = wf_utils:replace_with_base(Base1, Element), % Wire the actions... wf_context:anchor(Anchor), wf:wire(Base1#elementbase.actions), % Render the element... Html = call_element_render(render_element, Module, Element1), % Reset the anchor (likely changed during the inner render)... wf_context:anchor(Anchor), Html. extract_anchor(#elementbase{anchor=undefined}) -> normalize_id(temp_id()); extract_anchor(#elementbase{anchor=Anchor}) -> normalize_id(Anchor). % Get the ID, or use the anchor if it's not defined... extract_id(#elementbase{id=undefined}, Anchor) -> Anchor; extract_id(#elementbase{id=ID}, _Anchor) -> normalize_id(ID). extract_class(#elementbase{class=Class}, ID, Anchor) when ID==Anchor -> [ID, Class]; extract_class(#elementbase{class=Class}, ID, Anchor) -> [ID, Anchor, Class]. % call_element_render(RenderOrTransform, Module, Element) -> {ok, Html}. Calls % the render_element/3 function of an element to turn an element record into % HTML. -spec call_element_render(RenderOrTransform :: render_element | transform_element, Module :: module(), Element :: nitrogen_element() ) -> html(). call_element_render(RenderOrTransform, Module, Element) -> NewElements = Module:RenderOrTransform(Element), inner_render_elements(NewElements). -spec normalize_id(list() | atom() | binary()) -> string(). normalize_id(ID) -> case wf:to_string_list(ID) of [".wfid_" ++ _] = [NormalizedID] -> NormalizedID; ["page"] -> "page"; [NewID] -> ".wfid_" ++ NewID end. -spec temp_id() -> string(). temp_id() -> Num = ?WF_UNIQUE, %% For Erlang 18+, is erlang:unique_integer, %% For Erlang <18, is parts of erlang:now() %% see compat.escript, and include/compat.hrl for the %% definition. "temp" ++ integer_to_list(Num). recurse_body(Fun, List) when is_list(List) -> [recurse_body(Fun, X) || X <- List]; recurse_body(Fun, Rec0) when is_tuple(Rec0), element(2, Rec0)==is_element -> try Rec = Fun(Rec0), Mod = element(3, Rec), Fields = Mod:reflect(), case lists:member(body, Fields) of true -> Idx = wf_utils:indexof(body, Fields), Body = element(Idx, Rec), Body2 = recurse_body(Fun, Body), setelement(Idx, Rec, Body2); false -> Rec end catch E:T:S -> error_logger:warning_msg("Error trying to apply function to an element tuple: ~p~nError: ~p: ~p.~nStacktrace: ~p",[Rec0, E, T, S]), Rec0 end; recurse_body(_Fun, X) -> X.