Add optional validator to jinja2 render function

Author: rileykk

Diff for: requirements.txt

@@ -4,6 +4,7 @@ flake8-import-order
 h5py
 Jinja2==3.1.5
 jsonschema
+lxml
 mgrs
 numpy<2
 pandas

Diff for: src/opera/util/render_jinja2.py

@@ -12,15 +12,20 @@
 """
 
 import json
-import numpy as np
 import os
 import re
+
+from functools import partial
+
 import jinja2
+import yaml
+
+import numpy as np
 
+from lxml import etree
 from opera.util.error_codes import ErrorCode
 from opera.util.logger import PgeLogger
 
-
 XML_TYPES = {
     str: 'string',
     int: 'int',
@@ -87,18 +92,18 @@ def _log_message(undef):
     class LoggingUndefined(jinja2.Undefined):
         """Override the default behavior which can raise an exception"""
 
-        def _fail_with_undefined_error(self, *args, **kwargs):   # pragma no cover
+        def _fail_with_undefined_error(self, *args, **kwargs):  # pragma no cover
             _log_message(self)
 
         def __str__(self):
             _log_message(self)
             return UNDEFINED_ERROR
 
-        def __iter__(self):   # pragma no cover
+        def __iter__(self):  # pragma no cover
             _log_message(self)
             return super().__iter__()
 
-        def __bool__(self):   # pragma no cover
+        def __bool__(self):  # pragma no cover
             _log_message(self)
             return super().__bool__()
 
@@ -109,7 +114,21 @@ def __getattr__(self, name):
     return LoggingUndefined
 
 
-def render_jinja2(template_filename: str, input_data: dict, logger: PgeLogger = None):
+def _try_parse_xml_string(s: str):
+    _ = etree.fromstring(s.encode('utf-8'))
+
+
+JSON_VALIDATOR = json.loads
+YAML_VALIDATOR = partial(yaml.load, Loader=yaml.SafeLoader)
+XML_VALIDATOR = _try_parse_xml_string
+
+
+def render_jinja2(
+        template_filename: str,
+        input_data: dict,
+        logger: PgeLogger = None,
+        validator=None
+):
     """
     Renders from a jinja2 template using the specified input data.
     Writes the rendered output to the specified output file.
@@ -126,6 +145,9 @@ def render_jinja2(template_filename: str, input_data: dict, logger: PgeLogger =
         will not raise exceptions or abort rendering. If not provided,
         the default Jinja2 error handling will apply for such errors,
         possibly including raised exceptions.
+    validator:
+        Callable which, if provided, takes the rendered text as an input and
+        attempts to parse it. Must raise an exception if given invalid input.
 
     Returns
     -------
@@ -155,10 +177,17 @@ def render_jinja2(template_filename: str, input_data: dict, logger: PgeLogger =
 
     rendered_text = template.render(input_data)
 
+    if validator is not None:
+        try:
+            validator(rendered_text)
+        except Exception as err:
+            raise RuntimeError(f"Error rendering Jinja2 template: {err}") from err
+
     return rendered_text
 
 
 def python_type_to_xml_type(obj) -> str:
+    """Returns a guess for the XML type of a Python object."""
     if isinstance(obj, str):
         if obj.lower() in ['true', 'false']:
             obj = obj.lower() == 'true'
@@ -172,6 +201,7 @@ def python_type_to_xml_type(obj) -> str:
 
     return XML_TYPES[obj]
 
+
 class NumpyEncoder(json.JSONEncoder):
     """Class to handle serialization of Numpy types during JSON enconding"""
     def default(self, obj):
@@ -186,5 +216,9 @@ def default(self, obj):
         return super(NumpyEncoder, self).default(obj)
 
 def guess_attribute_display_name(var_name: str) -> str:
+    """
+    Returns an approximation of an Additional Attribute's display name from its attribute name by converting snake_case
+    to PascalCase.
+    Ex. sample_attribute_name -> SampleAttributeName
+    """
     return var_name.title().replace('_', '')
-