Support for including file contents as an array (#154)

docs/template-files.md

@@ -207,6 +207,17 @@ Resources:
       Runtime: "python3.7"
 ```
 
+### code_array
+
+Sometimes you might want to take the contents of a file as input for an array (line-by-line). Combine `code()` with `code_array` to make that happen:
+
+```yaml
+Resources:
+  ...
+  ListOfItems: {{ code('my-list') | code_array }}
+```
+
+
 
 ### file
 

formica/loader.py

@@ -41,6 +41,9 @@
 def code_escape(source):
     return source.replace("\n", "\\n").replace('"', '\\"')
 
+def code_array(source):
+    lines = source.split("\\n")
+    return '[' + ','.join(['"%s"' % line for line in lines]) + ']'
 
 def mandatory(a):
     from jinja2.runtime import Undefined
@@ -69,9 +72,13 @@ def __init__(self, path=".", filename="*", variables=None, main_account_paramete
         self.path = path
         self.filename = filename
         self.env = Environment(loader=FileSystemLoader("./", followlinks=True))
-        self.env.filters.update(
-            {"code_escape": code_escape, "mandatory": mandatory, "resource": resource, "novalue": novalue}
-        )
+        self.env.filters.update({
+            "code_escape": code_escape, 
+            "code_array": code_array, 
+            "mandatory": mandatory, 
+            "resource": resource, 
+            "novalue": novalue,
+        })
         self.variables = variables
         self.main_account_parameter = main_account_parameter
 

tests/unit/test_loader.py

@@ -333,6 +333,19 @@ def test_code_includes_and_escapes_code(load, tmpdir):
     assert actual == {"Description": "test\n\"something\""}
 
 
+def test_code_with_code_array(load, tmpdir):
+    example = '{"Resources": {"Test": {{ code("test.py") | code_array }} }}'
+    pycode = "test\n\"something\"\nanother line"
+    with Path(tmpdir):
+        with open('test.template.json', 'w') as f:
+            f.write(example)
+        with open('test.py', 'w') as f:
+            f.write(pycode)
+        load.load()
+        actual = json.loads(load.template())
+    assert actual == {"Resources": {"Test": ["test", "\"something\"", "another line"]}}
+
+
 def test_code_allows_to_include_files_from_parent(load, tmpdir):
     parent = '{"Resources": {"Test": {"From": "Moduledir"}}}'
     module = '{"Description": "{{ code("../test.txt") }}"}'