def auto_converter(tt):
'''Auto convert attempt a number of ways of finding appropriate converters
to a unhandled type.
The first strategy is to check if the type is supported in the
mod:`pyson.jsonfy_extras` module.
If that is not the case, it searches for converters for the superclasses
of `tt`.
Finally, if that fails an error is raised.
'''
# Tries to import a converter from jsonfy_ext.* modules
name = type2name(tt)
try:
load_modules('pyson.jsonfy_extras.ext_' + name)
except AttributeError:
pass
try:
return CONVERTERS[tt]
except KeyError:
pass
# Tries to use a converter for a base class (hint: this often fails!)
for base_t in tt.mro()[:-1]:
try:
return CONVERTERS[base_t]
except KeyError:
pass
else:
raise TypeError('object of type %s is not supported' % tt)
def not_supported(obj):
raise TypeError('object of type %s is not supported' % tt)
return not_supported
def jsonfy(obj, json_level=None, print_type=True, invertible=False, recursive=True):
'''Return a JSON representation of object.
Parameters
----------
obj : anything
Object to be converted to JSON
json_level : int
Maximum JSON level allowed for the given type.
print_type : bool
Set to False to prevent adding the ('@type': value) pair to the
resulting object. This key is used to convert the JSON object to
the appropriate Python type.
invertible : bool
If True, the output can be converted back to an identical Python object.
The default behavior is to allow approximate types, e.g., ``str``
can be converted to ``unicode``, ``tuple`` to ``list`` and so on.
recursive : bool
If False and json_level is respected or not set, it prevents recursive
application of func:`jsonfy` to child nodes of the JSON result.
'''
tt = type(obj)
if json_level is not None or invertible:
raise NotImplementedError
# Compute the result from the converter function
try:
function = CONVERTERS[tt]
except KeyError:
function = auto_converter(tt)
try:
result = function(obj)
except Exception as ex:
msg = 'unhandled exception raised when jsonfy-ing %s object\n %s: %s'
msg = msg % (type(obj), type(ex).__name__, ex)
raise RuntimeError(msg)
# Print type
if print_type and not is_object_t(tt):
try:
result[u'@type'] = type2name(tt)
except:
pass
#TODO: move recursive to converter function
if recursive:
if isinstance(result, dict):
for k, v in result.items():
result[k] = jsonfy(v, json_level=json_level, print_type=print_type,
invertible=invertible, recursive=recursive)
elif isinstance(result, list):
for idx, v in enumerate(result):
result[idx] = jsonfy(v, json_level=json_level, print_type=print_type,
invertible=invertible, recursive=recursive)
return result
def unjsonfy(json, tt=None, recursive=True, inplace=False, lazy=True):
"""Create object from its JSON representation
Parameters
----------
json : JSON-like
JSON-like structure to be converted to a Python object.
tt (optional): type
Type of the output object (can be inferred from the '@type' key, if
``json`` has it.
recursive : bool
If False, prevents recursive application of func:`jsonfy` to child nodes
of the JSON input.
"""
if tt is None:
try:
tt = json[u"@type"]
except:
if not lazy:
raise ValueError("'tt' must be set explicity if 'json' does not have a '@type' key")
else:
tt = None
else:
tt = name2type(tt)
# TODO: move 'inplace' and 'recursive' to the converter function
if not inplace:
json = deepcopy(json)
if recursive:
if isinstance(json, dict):
for k, v in json.items():
json[k] = unjsonfy(v, recursive=True, inplace=True)
elif isinstance(json, list):
for idx, v in enumerate(json):
json[idx] = unjsonfy(v, recursive=True, inplace=True)
# Compute the result from the converter function
try:
converter = CONVERTERS[tt]
except KeyError:
# Tries to load converters from unjsonfy_extras
try:
load_modules("pyson.unjsonfy_extras.ext_" + type2name(tt))
except AttributeError:
pass
try:
converter = CONVERTERS[tt]
except KeyError:
if tt is None:
return json
raise ValueError("there is no known converter to type %s" % tt)
return converter(json)
def unjsonfy(json, tt=None, recursive=True, inplace=False, lazy=True):
'''Create object from its JSON representation
Parameters
----------
json : JSON-like
JSON-like structure to be converted to a Python object.
tt (optional): type
Type of the output object (can be inferred from the '@type' key, if
``json`` has it.
recursive : bool
If False, prevents recursive application of func:`jsonfy` to child nodes
of the JSON input.
'''
if tt is None:
try:
tt = json[u'@type']
except:
if not lazy:
raise ValueError("'tt' must be set explicity if 'json' does not have a '@type' key")
else:
tt = None
else:
tt = name2type(tt)
#TODO: move 'inplace' and 'recursive' to the converter function
if not inplace:
json = deepcopy(json)
if recursive:
if isinstance(json, dict):
for k, v in json.items():
json[k] = unjsonfy(v, recursive=True, inplace=True)
elif isinstance(json, list):
for idx, v in enumerate(json):
json[idx] = unjsonfy(v, recursive=True, inplace=True)
# Compute the result from the converter function
try:
converter = CONVERTERS[tt]
except KeyError:
# Tries to load converters from unjsonfy_extras
try: load_modules('pyson.unjsonfy_extras.ext_' + type2name(tt))
except AttributeError: pass
try:
converter = CONVERTERS[tt]
except KeyError:
if tt is None:
return json
raise ValueError('there is no known converter to type %s' % tt)
return converter(json)
def auto_converter(tt):
'''Auto convert attempt a number of ways of finding appropriate converters
to a unhandled type.
The first strategy is to check if the type is supported in the
mod:`pyson.jsonfy_extras` module.
If that is not the case, it searches for converters for the superclasses
of `tt`.
Finally, if that fails an error is raised.
'''
# Tries to import a converter from jsonfy_ext.* modules
name = type2name(tt)
try:
load_modules('pyson.jsonfy_extras.ext_' + name)
except AttributeError:
pass
try:
return CONVERTERS[tt]
except KeyError:
pass
# Tries to use a converter for a base class (hint: this often fails!)
for base_t in tt.mro()[:-1]:
try:
return CONVERTERS[base_t]
except KeyError:
pass
else:
raise TypeError('object of type %s is not supported' % tt)
def not_supported(obj):
raise TypeError('object of type %s is not supported' % tt)
return not_supported
def jsonfy(obj,
json_level=None,
print_type=True,
invertible=False,
recursive=True):
'''Return a JSON representation of object.
Parameters
----------
obj : anything
Object to be converted to JSON
json_level : int
Maximum JSON level allowed for the given type.
print_type : bool
Set to False to prevent adding the ('@type': value) pair to the
resulting object. This key is used to convert the JSON object to
the appropriate Python type.
invertible : bool
If True, the output can be converted back to an identical Python object.
The default behavior is to allow approximate types, e.g., ``str``
can be converted to ``unicode``, ``tuple`` to ``list`` and so on.
recursive : bool
If False and json_level is respected or not set, it prevents recursive
application of func:`jsonfy` to child nodes of the JSON result.
'''
tt = type(obj)
if json_level is not None or invertible:
raise NotImplementedError
# Compute the result from the converter function
try:
function = CONVERTERS[tt]
except KeyError:
function = auto_converter(tt)
try:
result = function(obj)
except Exception as ex:
msg = 'unhandled exception raised when jsonfy-ing %s object\n %s: %s'
msg = msg % (type(obj), type(ex).__name__, ex)
raise RuntimeError(msg)
# Print type
if print_type and not is_object_t(tt):
try:
result[u'@type'] = type2name(tt)
except:
pass
#TODO: move recursive to converter function
if recursive:
if isinstance(result, dict):
for k, v in result.items():
result[k] = jsonfy(v,
json_level=json_level,
print_type=print_type,
invertible=invertible,
recursive=recursive)
elif isinstance(result, list):
for idx, v in enumerate(result):
result[idx] = jsonfy(v,
json_level=json_level,
print_type=print_type,
invertible=invertible,
recursive=recursive)
return result
