From 235ccf23b16f1879e6b4b9947f4e9d2ab4d1d11e Mon Sep 17 00:00:00 2001
From: Marc Worrell <marc@worrell.nl>
Date: Tue, 26 Nov 2024 11:19:17 +0100
Subject: [PATCH] Allow 'undefined' for include templates

---
 src/template_compiler_runtime_internal.erl | 38 ++++++++++++++++++++--
 test/template_compiler_include_SUITE.erl   |  6 ++++
 test/test-data/include_undefined.tpl       |  1 +
 3 files changed, 42 insertions(+), 3 deletions(-)
 create mode 100644 test/test-data/include_undefined.tpl

diff --git a/src/template_compiler_runtime_internal.erl b/src/template_compiler_runtime_internal.erl
index d767e2a..b9d17c1 100644
--- a/src/template_compiler_runtime_internal.erl
+++ b/src/template_compiler_runtime_internal.erl
@@ -201,9 +201,41 @@ block_inherit(SrcPos, Module, Block, Vars, BlockMap, Runtime, Context) ->
 
 
 %% @doc Include a template.
--spec include({File::binary(), Line::integer(), Col::integer()}, normal|optional|all,
-        template_compiler:template(), list({atom(),term()}), atom(), list(binary()), boolean(), map(), term()) ->
-        template_compiler:render_result().
+-spec include(SrcPos, Method, Template, Args, Runtime, ContextVars, IsContextVars, Vars, Context) -> Output when
+    SrcPos :: {File::binary(), Line::integer(), Col::integer()},
+    Method :: normal | optional | all,
+    Template :: template_compiler:template() | undefined,
+    Args :: list({atom(),term()}),
+    Runtime :: atom(),
+    ContextVars :: list(binary()),
+    IsContextVars :: boolean(),
+    Vars :: map(),
+    Context :: term(),
+    Output :: template_compiler:render_result().
+include(SrcPos, normal, undefined, _Args, _Runtime, _ContextVars, _IsContextVars, _Vars, _Context) ->
+    {SrcFile, SrcLine, _SrcCol} = SrcPos,
+    ?LOG_ERROR(#{
+        text => <<"Included template not found">>,
+        template => undefined,
+        srcpos => SrcPos,
+        result => error,
+        reason => enoent,
+        at => SrcFile,
+        line => SrcLine
+    }),
+    <<>>;
+include(SrcPos, _Method, undefined, _Args, _Runtime, _ContextVars, _IsContextVars, _Vars, _Context) ->
+    {SrcFile, SrcLine, _SrcCol} = SrcPos,
+    ?LOG_DEBUG(#{
+        text => <<"Included template not found">>,
+        template => undefined,
+        srcpos => SrcPos,
+        result => error,
+        reason => enoent,
+        at => SrcFile,
+        line => SrcLine
+    }),
+    <<>>;
 include(SrcPos, Method, Template, Args, Runtime, ContextVars, IsContextVars, Vars, Context) ->
     Vars1 = lists:foldl(
                 fun
diff --git a/test/template_compiler_include_SUITE.erl b/test/template_compiler_include_SUITE.erl
index bbadeeb..3bb9bc7 100644
--- a/test/template_compiler_include_SUITE.erl
+++ b/test/template_compiler_include_SUITE.erl
@@ -22,6 +22,7 @@ groups() ->
         [include_test
         ,include_dynamic_test
         ,include_args_test
+        ,include_undefined_test
         ,compose_test
         ,compose_inherit_test
         ]}].
@@ -74,6 +75,11 @@ include_args_test(_Config) ->
     <<"a3:2:truec">> = iolist_to_binary(Bin1),
     ok.
 
+include_undefined_test(_Config) ->
+    {ok, Bin1} = template_compiler:render("include_undefined.tpl", #{ template => undefined }, [], undefined),
+    <<"ac">> = iolist_to_binary(Bin1),
+    ok.
+
 compose_test(_Config) ->
     {ok, Bin1} = template_compiler:render("compose.tpl", #{}, [], undefined),
     <<"AxB1yC">> = iolist_to_binary(Bin1),
diff --git a/test/test-data/include_undefined.tpl b/test/test-data/include_undefined.tpl
new file mode 100644
index 0000000..73e7833
--- /dev/null
+++ b/test/test-data/include_undefined.tpl
@@ -0,0 +1 @@
+a{% include template %}c
\ No newline at end of file