How to validate structure (or schema) of dictionary in Python?

You may use schema (PyPi Link)

schema is a library for validating Python data structures, such as those obtained from config-files, forms, external services or command-line parsing, converted from JSON/YAML (or something else) to Python data-types.

from schema import Schema, And, Use, Optional, SchemaErrordef check(conf_schema, conf):    try:        conf_schema.validate(conf)        return True    except SchemaError:        return Falseconf_schema = Schema({    'version': And(Use(int)),    'info': {        'conf_one': And(Use(float)),        'conf_two': And(Use(str)),        'conf_three': And(Use(bool)),        Optional('optional_conf'): And(Use(str))    }})conf = {    'version': 1,    'info': {        'conf_one': 2.5,        'conf_two': 'foo',        'conf_three': False,        'optional_conf': 'bar'    }}print(check(conf_schema, conf))

Without using libraries, you could also define a simple recursive function like this:

def check_structure(struct, conf):    if isinstance(struct, dict) and isinstance(conf, dict):        # struct is a dict of types or other dicts        return all(k in conf and check_structure(struct[k], conf[k]) for k in struct)    if isinstance(struct, list) and isinstance(conf, list):        # struct is list in the form [type or dict]        return all(check_structure(struct[0], c) for c in conf)    elif isinstance(struct, type):        # struct is the type of conf        return isinstance(conf, struct)    else:        # struct is neither a dict, nor list, not type        return False

This assumes that the config can have keys that are not in your structure, as in your example.

Update: New version also supports lists, e.g. like 'foo': [{'bar': int}]

You can build structure using recursion:

def get_type(value):    if isinstance(value, dict):        return {key: get_type(value[key]) for key in value}    else:        return str(type(value))

And then compare required structure with your dictionary:

get_type(current_conf) == get_type(required_conf)

Example:

required_conf = {    'version': 1,    'info': {        'conf_one': 2.5,        'conf_two': 'foo',        'conf_three': False,        'optional_conf': 'bar'    }}get_type(required_conf){'info': {'conf_two': "<type 'str'>", 'conf_one': "<type 'float'>", 'optional_conf': "<type 'str'>", 'conf_three': "<type 'bool'>"}, 'version': "<type 'int'>"}