Source code for pygeoapi.util

# =================================================================
#
# Authors: Tom Kralidis <[email protected]>
#
# Copyright (c) 2020 Tom Kralidis
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"""Generic util functions used in the code"""

from datetime import date, datetime, time
from decimal import Decimal
import json
import logging
import mimetypes
import os
import re
from urllib.parse import urlparse

from jinja2 import Environment, FileSystemLoader
import yaml

from pygeoapi import __version__

LOGGER = logging.getLogger(__name__)

TEMPLATES = '{}{}templates'.format(os.path.dirname(
    os.path.realpath(__file__)), os.sep)

mimetypes.add_type('text/plain', '.yaml')
mimetypes.add_type('text/plain', '.yml')


[docs]def dategetter(date_property, collection): """ Attempts to obtains a date value from a collection. :param date_property: property representing the date :param collection: dictionary to check within :returns: `str` (ISO8601) representing the date. ('..' if null or "now", allowing for an open interval). """ value = collection.get(date_property, None) if value == 'now' or value is None: return '..' return value.isoformat()
[docs]def get_typed_value(value): """ Derive true type from data value :param value: value :returns: value as a native Python data type """ try: if '.' in value: # float? value2 = float(value) elif len(value) > 1 and value.startswith('0'): value2 = value else: # int? value2 = int(value) except ValueError: # string (default)? value2 = value return value2
[docs]def yaml_load(fh): """ serializes a YAML files into a pyyaml object :param fh: file handle :returns: `dict` representation of YAML """ # support environment variables in config # https://stackoverflow.com/a/55301129 path_matcher = re.compile(r'.*\$\{([^}^{]+)\}.*') def path_constructor(loader, node): env_var = path_matcher.match(node.value).group(1) if env_var not in os.environ: raise EnvironmentError('Undefined environment variable in config') return get_typed_value(os.path.expandvars(node.value)) class EnvVarLoader(yaml.SafeLoader): pass EnvVarLoader.add_implicit_resolver('!path', path_matcher, None) EnvVarLoader.add_constructor('!path', path_constructor) return yaml.load(fh, Loader=EnvVarLoader)
[docs]def str2bool(value): """ helper function to return Python boolean type (source: https://stackoverflow.com/a/715468) :param value: value to be evaluated :returns: `bool` of whether the value is boolean-ish """ value2 = False if isinstance(value, bool): value2 = value else: value2 = value.lower() in ('yes', 'true', 't', '1', 'on') return value2
[docs]def to_json(dict_): """ Serialize dict to json :param dict_: `dict` of JSON representation :returns: JSON string representation """ return json.dumps(dict_, default=json_serial)
[docs]def json_serial(obj): """ helper function to convert to JSON non-default types (source: https://stackoverflow.com/a/22238613) :param obj: `object` to be evaluated :returns: JSON non-default type to `str` """ if isinstance(obj, (datetime, date, time)): return obj.isoformat() elif isinstance(obj, Decimal): return float(obj) msg = '{} type {} not serializable'.format(obj, type(obj)) LOGGER.error(msg) raise TypeError(msg)
[docs]def is_url(urlstring): """ Validation function that determines whether a candidate URL should be considered a URI. No remote resource is obtained; this does not check the existence of any remote resource. :param urlstring: `str` to be evaluated as candidate URL. :returns: `bool` of whether the URL looks like a URL. """ try: result = urlparse(urlstring) return bool(result.scheme and result.netloc) except ValueError: return False
[docs]def render_j2_template(config, template, data): """ render Jinja2 template :param config: dict of configuration :param template: template (relative path) :param data: dict of data :returns: string of rendered template """ env = Environment(loader=FileSystemLoader(TEMPLATES)) env.filters['to_json'] = to_json env.globals.update(to_json=to_json) template = env.get_template(template) return template.render(config=config, data=data, version=__version__)
[docs]def get_mimetype(filename): """ helper function to return MIME type of a given file :param filename: filename (with extension) :returns: MIME type of given filename """ return mimetypes.guess_type(filename)[0]