What is json loads in python?
JSON is a syntax for storing and exchanging data. Show
JSON is text, written with JavaScript object notation. JSON in PythonPython has a built-in package called ExampleImport the json module: import json Parse JSON - Convert from JSON to PythonIf you have a JSON string, you can parse it by using the ExampleConvert from JSON to Python: import json # some JSON: # parse x: # the result is a Python dictionary: Try it Yourself » Convert from Python to JSONIf you have a Python object, you can convert it into a JSON string by using the ExampleConvert from Python to JSON: import json # a Python object (dict): # convert into JSON: # the result is a JSON string: Try it Yourself » You can convert Python objects of the following types, into JSON strings:
ExampleConvert Python objects into JSON strings, and print the values: import json print(json.dumps({"name": "John", "age": 30})) Try it Yourself » When you convert from Python to JSON, Python objects are converted into the JSON (JavaScript) equivalent:
ExampleConvert a Python object containing all the legal data types: import json x = { print(json.dumps(x)) Try it Yourself » Format the ResultThe example above prints a JSON string, but it is not very easy to read, with no indentations and line breaks. The ExampleUse the json.dumps(x, indent=4) Try it Yourself » You can also define the separators, default value is (", ", ": "), which means using a comma and a space to separate each object, and a colon and a space to separate keys from values: ExampleUse the json.dumps(x, indent=4, separators=(". ", " = ")) Try it Yourself » Order the ResultThe ExampleUse the json.dumps(x, indent=4, sort_keys=True) Try it Yourself » Source code: Lib/json/__init__.py JSON (JavaScript Object Notation), specified by RFC 7159 (which obsoletes RFC 4627) and by ECMA-404, is a lightweight data interchange format inspired by JavaScript object literal syntax (although it is not a strict subset of JavaScript 1 ). Warning Be cautious when parsing JSON data from untrusted sources. A malicious JSON string may cause the decoder to consume considerable CPU and memory resources. Limiting the size of data to be parsed is recommended.
Encoding basic Python object hierarchies: >>> import json >>> json.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}]) '["foo", {"bar": ["baz", null, 1.0, 2]}]' >>> print(json.dumps("\"foo\bar")) "\"foo\bar" >>> print(json.dumps('\u1234')) "\u1234" >>> print(json.dumps('\\')) "\\" >>> print(json.dumps({"c": 0, "b": 0, "a": 0}, sort_keys=True)) {"a": 0, "b": 0, "c": 0} >>> from io import StringIO >>> io = StringIO() >>> json.dump(['streaming API'], io) >>> io.getvalue() '["streaming API"]' Compact encoding: >>> import json >>> json.dumps([1, 2, 3, {'4': 5, '6': 7}], separators=(',', ':')) '[1,2,3,{"4":5,"6":7}]' Pretty printing: >>> import json >>> print(json.dumps({'4': 5, '6': 7}, sort_keys=True, indent=4)) { "4": 5, "6": 7 } Decoding JSON: >>> import json >>> json.loads('["foo", {"bar":["baz", null, 1.0, 2]}]') ['foo', {'bar': ['baz', None, 1.0, 2]}] >>> json.loads('"\\"foo\\bar"') '"foo\x08ar' >>> from io import StringIO >>> io = StringIO('["streaming API"]') >>> json.load(io) ['streaming API'] Specializing JSON object decoding: >>> import json >>> def as_complex(dct): ... if '__complex__' in dct: ... return complex(dct['real'], dct['imag']) ... return dct ... >>> json.loads('{"__complex__": true, "real": 1, "imag": 2}', ... object_hook=as_complex) (1+2j) >>> import decimal >>> json.loads('1.1', parse_float=decimal.Decimal) Decimal('1.1') Extending >>> import json >>> class ComplexEncoder(json.JSONEncoder): ... def default(self, obj): ... if isinstance(obj, complex): ... return [obj.real, obj.imag] ... # Let the base class default method raise the TypeError ... return json.JSONEncoder.default(self, obj) ... >>> json.dumps(2 + 1j, cls=ComplexEncoder) '[2.0, 1.0]' >>> ComplexEncoder().encode(2 + 1j) '[2.0, 1.0]' >>> list(ComplexEncoder().iterencode(2 + 1j)) ['[2.0', ', 1.0', ']'] Using
$ echo '{"json":"obj"}' | python -m json.tool { "json": "obj" } $ echo '{1.2:3.4}' | python -m json.tool Expecting property name enclosed in double quotes: line 1 column 2 (char 1) See Command Line Interface for detailed documentation. Note JSON is a subset of YAML 1.2. The JSON produced by this module’s default settings (in particular, the default separators value) is also a subset of YAML 1.0 and 1.1. This module can thus also be used as a YAML serializer. Note This module’s encoders and decoders preserve input and output order by default. Order is only lost if the underlying containers are unordered. Basic Usage¶json. dump (obj, fp, *, skipkeys=False, ensure_ascii=True, check_circular=True,
allow_nan=True, cls=None, indent=None, separators=None, default=None, sort_keys=False,
**kw)¶Serialize obj as a JSON formatted stream to fp (a If skipkeys is true (default: The
If ensure_ascii is true (the default), the output is guaranteed to have all incoming non-ASCII characters escaped. If ensure_ascii is false, these characters will be output as-is. If check_circular is false (default: If allow_nan is false (default: If indent is a non-negative integer or string, then JSON array elements and object members will be pretty-printed with that indent level. An indent level of 0, negative, or Changed in version 3.2: Allow strings for indent in addition to integers. If specified, separators should be an Changed
in version 3.4: Use If specified, default should be a function that gets called for objects that can’t otherwise be serialized. It should return a JSON encodable version of the object or raise a If sort_keys is true (default: To use a custom Changed in version 3.6: All optional parameters are now keyword-only. Note Unlike
json. dumps (obj, *, skipkeys=False, ensure_ascii=True, check_circular=True,
allow_nan=True, cls=None, indent=None, separators=None, default=None, sort_keys=False,
**kw)¶Serialize obj to a JSON formatted Note Keys in key/value pairs of JSON are always of the type json. load (fp, *, cls=None, object_hook=None, parse_float=None, parse_int=None,
parse_constant=None, object_pairs_hook=None, **kw)¶Deserialize fp (a object_hook is an optional function that will be called with the result of any object literal decoded (a
object_pairs_hook is an optional function that will be called
with the result of any object literal decoded with an ordered list of pairs. The return value of object_pairs_hook will be used instead of the Changed in version 3.1: Added support for object_pairs_hook. parse_float,
if specified, will be called with the string of every JSON float to be decoded. By default, this is equivalent to parse_int, if specified, will be called with the string of every JSON int to be decoded. By default, this is equivalent to Changed in version 3.10.7: The default parse_int of parse_constant, if specified, will be called with one of the following strings: Changed in version 3.1: parse_constant doesn’t get called on ‘null’, ‘true’, ‘false’ anymore. To use a custom If the data being deserialized is not a valid JSON
document, a Changed in version 3.6: All optional parameters are now keyword-only. Changed in version 3.6: fp can now be a binary file. The input encoding should be UTF-8, UTF-16 or UTF-32. json. loads (s, *, cls=None, object_hook=None, parse_float=None,
parse_int=None, parse_constant=None, object_pairs_hook=None, **kw)¶Deserialize s (a
The other arguments have the same meaning as in If the data being deserialized is not a valid JSON document, a Changed in version 3.6: s can now be of type
Changed in version 3.9: The keyword argument encoding has been removed. Encoders and Decoders¶classjson. JSONDecoder (*, object_hook=None, parse_float=None, parse_int=None,
parse_constant=None, strict=True, object_pairs_hook=None)¶Simple JSON decoder. Performs the following translations in decoding by default:
It also understands object_hook, if specified, will be called with the result of every JSON object decoded and its return value will be used in place of the given object_pairs_hook, if specified will be called with the result of every JSON object decoded with an ordered list of pairs. The return value of object_pairs_hook will be used instead of the Changed in version 3.1: Added support for object_pairs_hook. parse_float, if specified, will be called with the string of every JSON float to be decoded. By default, this is equivalent to parse_int,
if specified, will be called with the string of every JSON int to be decoded. By default, this is equivalent to parse_constant, if specified, will be called with one of the following strings: If strict is false ( If the data being deserialized is not a valid JSON document, a Changed in version 3.6: All parameters are now keyword-only. decode (s)¶Return the Python representation of s (a
raw_decode (s)¶Decode a JSON document from s (a This can be used to decode a JSON document from a string that may have extraneous data at the end. classjson. JSONEncoder (*, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True,
sort_keys=False, indent=None, separators=None, default=None)¶Extensible JSON encoder for Python data structures. Supports the following objects and types by default:
Changed in version 3.4: Added support for int- and float-derived Enum classes. To extend this to recognize other objects, subclass and implement a If skipkeys is false (the default), a If ensure_ascii is true (the default), the output is guaranteed to have all incoming non-ASCII characters escaped. If ensure_ascii is false, these characters will be output as-is. If
check_circular is true (the default), then lists, dicts, and custom encoded objects will be checked for circular references during encoding to prevent an infinite recursion (which would cause an If allow_nan is true (the default), then If sort_keys is true (default: If
indent is a non-negative integer or string, then JSON array elements and object members will be pretty-printed with that indent level. An indent level of 0, negative, or Changed in version 3.2: Allow strings for indent in addition to integers. If specified, separators should be an Changed in version 3.4: Use If specified, default should be a function that gets called for objects that can’t otherwise be
serialized. It should return a JSON encodable version of the object or raise a Changed in version 3.6: All parameters are now keyword-only. default (o)¶Implement this method in a subclass such that it returns a serializable object for o, or calls the base implementation
(to raise a For example, to support arbitrary iterators, you could implement def default(self, o): try: iterable = iter(o) except TypeError: pass else: return list(iterable) # Let the base class default method raise the TypeError return json.JSONEncoder.default(self, o) encode (o)¶Return a JSON string representation of a Python data structure, o. For example: >>> json.JSONEncoder().encode({"foo": ["bar", "baz"]}) '{"foo": ["bar", "baz"]}' iterencode (o)¶Encode the given object, o, and yield each string representation as available. For example: for chunk in json.JSONEncoder().iterencode(bigobject): mysocket.write(chunk) Exceptions¶exceptionjson. JSONDecodeError (msg, doc, pos)¶Subclass of
msg ¶The unformatted error message. doc ¶The JSON document being parsed. pos ¶The start index of doc where parsing failed. lineno ¶The line corresponding to pos. colno ¶The column corresponding to pos. New in version 3.5. Standard Compliance and Interoperability¶The JSON format is specified by RFC 7159 and by
ECMA-404. This section details this module’s level of compliance with the RFC. For simplicity, This module does not comply with the RFC in a strict fashion, implementing some extensions that are valid JavaScript but not valid JSON. In particular:
Since the RFC permits RFC-compliant parsers to accept input texts that are not RFC-compliant, this module’s deserializer is technically RFC-compliant under default settings. Character Encodings¶The RFC requires that JSON be represented using either UTF-8, UTF-16, or UTF-32, with UTF-8 being the recommended default for maximum interoperability. As permitted, though not required, by the RFC, this module’s serializer sets ensure_ascii=True by default, thus escaping the output so that the resulting strings only contain ASCII characters. Other than the ensure_ascii parameter, this module is defined strictly in terms of conversion between Python objects and The RFC prohibits
adding a byte order mark (BOM) to the start of a JSON text, and this module’s serializer does not add a BOM to its output. The RFC permits, but does not require, JSON deserializers to ignore an initial BOM in their input. This module’s deserializer raises a The RFC does not explicitly forbid JSON strings which contain byte sequences that
don’t correspond to valid Unicode characters (e.g. unpaired UTF-16 surrogates), but it does note that they may cause interoperability problems. By default, this module accepts and outputs (when present in the original Infinite and NaN Number Values¶The RFC does not permit the representation of infinite or NaN number values. Despite that, by default, this module accepts and outputs >>> # Neither of these calls raises an exception, but the results are not valid JSON >>> json.dumps(float('-inf')) '-Infinity' >>> json.dumps(float('nan')) 'NaN' >>> # Same when deserializing >>> json.loads('-Infinity') -inf >>> json.loads('NaN') nan In the serializer, the allow_nan parameter can be used to alter this behavior. In the deserializer, the parse_constant parameter can be used to alter this behavior. Repeated Names Within an Object¶The RFC specifies that the names within a JSON object should be unique, but does not mandate how repeated names in JSON objects should be handled. By default, this module does not raise an exception; instead, it ignores all but the last name-value pair for a given name: >>> weird_json = '{"x": 1, "x": 2, "x": 3}' >>> json.loads(weird_json) {'x': 3} The object_pairs_hook parameter can be used to alter this behavior. Top-level Non-Object, Non-Array Values¶The old version of JSON
specified by the obsolete RFC 4627 required that the top-level value of a JSON text must be either a JSON object or array (Python Regardless, for maximum interoperability, you may wish to voluntarily adhere to the restriction yourself. Implementation Limitations¶Some JSON deserializer implementations may set limits on:
This module does not impose any such limits beyond those of the relevant Python datatypes themselves or the Python interpreter itself. When serializing to JSON, beware any such limitations in applications that may consume your JSON. In particular, it is common for JSON numbers to be deserialized into IEEE 754 double precision numbers and thus subject to that representation’s range and precision limitations. This is especially relevant when serializing Python
Command Line Interface¶Source code: Lib/json/tool.py The If the optional $ echo '{"json": "obj"}' | python -m json.tool { "json": "obj" } $ echo '{1.2:3.4}' | python -m json.tool Expecting property name enclosed in double quotes: line 1 column 2 (char 1) Changed in version 3.5: The output is now in the same order as the input. Use
the Command line options¶infile ¶The JSON file to be validated or pretty-printed: $ python -m json.tool mp_films.json [ { "title": "And Now for Something Completely Different", "year": 1971 }, { "title": "Monty Python and the Holy Grail", "year": 1975 } ] If infile is not specified, read from outfile ¶Write the output of the infile to the given outfile. Otherwise, write it to --sort-keys ¶Sort the output of dictionaries alphabetically by key. New in version 3.5. --no-ensure-ascii ¶Disable escaping of non-ascii characters, see New in version 3.9. --json-lines ¶Parse every input line as separate JSON object. New in version 3.8. --indent
, --tab
, --no-indent
, --compact ¶Mutually exclusive options for whitespace control. New in version 3.9. -h
, --help ¶
Show the help message. Footnotes 1As noted in the errata for RFC 7159, JSON permits literal U+2028 (LINE SEPARATOR) and U+2029 (PARAGRAPH SEPARATOR) characters in strings, whereas JavaScript (as of ECMAScript Edition 5.1) does not. What is JSON load and loads?load() and json. loads() methods to read JSON data from file and String. Using the json. load() and json. loads() method, you can turn JSON encoded/formatted data into Python Types this process is known as JSON decoding.
What is JSON dumps and JSON loads?json loads -> returns an object from a string representing a json object. json dumps -> returns a string representing a json object from an object. load and dump -> read/write from/to file instead of string.
What is JSON in Python used for?JavaScript Object Notation (JSON) is a standardized format commonly used to transfer data as text that can be sent over a network. It's used by lots of APIs and Databases, and it's easy for both humans and machines to read. JSON represents objects as name/value pairs, just like a Python dictionary.
What is JSON dumps in Python?The json. dumps() method allows us to convert a python object into an equivalent JSON object. Or in other words to send the data from python to json. The json. dump() method allows us to convert a python object into an equivalent JSON object and store the result into a JSON file at the working directory.
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