Created
September 9, 2015 22:10
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PyYAML: raise exception on duplicate keys on the same document hierarchy level
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import yaml | |
from yaml.constructor import ConstructorError | |
try: | |
from yaml import CLoader as Loader | |
except ImportError: | |
from yaml import Loader | |
def no_duplicates_constructor(loader, node, deep=False): | |
"""Check for duplicate keys.""" | |
mapping = {} | |
for key_node, value_node in node.value: | |
key = loader.construct_object(key_node, deep=deep) | |
value = loader.construct_object(value_node, deep=deep) | |
if key in mapping: | |
raise ConstructorError("while constructing a mapping", node.start_mark, | |
"found duplicate key (%s)" % key, key_node.start_mark) | |
mapping[key] = value | |
return loader.construct_mapping(node, deep) | |
yaml.add_constructor(yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG, no_duplicates_constructor) | |
# Works fine (no duplicate keys) | |
yaml_data = yaml.load(''' | |
--- | |
foo: bar | |
baz: qux | |
''' | |
) | |
# Works fine (no duplicate keys on the same level) | |
yaml_data = yaml.load(''' | |
--- | |
foo: | |
bar: baz | |
baz: qux | |
bar: | |
bar: baz | |
baz: qux | |
''' | |
) | |
# Raises exception (has duplicate keys) | |
yaml_data = yaml.load(''' | |
--- | |
foo: bar | |
foo: qux | |
''' | |
) |
based on pbsds,we can deal merge keys like this
class UniqueKeyLoader(yaml.SafeLoader):
def construct_mapping(self, node, deep=False):
mapping = set()
for key_node, value_node in node.value:
if ':merge' in key_node.tag:
continue
key = self.construct_object(key_node, deep=deep)
if key in mapping:
raise ValueError(f"Duplicate {key!r} key found in YAML.")
mapping.add(key)
return super().construct_mapping(node, deep)
# other code
yaml_dic=yaml.load(yaml_file,Loader=UniqueKeyLoader)
Nice! Thanks guys!
It does not seem to work when the duplicate key comes from an anchor:
build_template: &BUILD_TEMPLATE
eks_container:
cpu: 4
build_task:
eks_container:
cpu: 10
env:
DEPLOY_PULL_REQUEST: true
BUILD_ARGUMENTS: "-DtrafficInspection=false --parallel --profile -x test -x sonar"
<<: *BUILD_TEMPLATE # Duplicate key eks_container and CPU not detected
Any idea on how to support this case?
Thanks.
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Minor optimization of ^ using sets instead of lists, that throws a
ValueError
instead of anAssertionError
Python 3.6+ only due to f-strings