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This article mainly explains "A brief introduction to json in python". The content of the explanation in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "A brief introduction to json in python".

A preface

Recently, we have been doing development related work-Django-based web platform, in which we need to transfer data from the model layer to the view layer for data presentation or business logic processing. We adopt the general Json format-Json (JavaScript Object Notation) is a lightweight data exchange format that is easy to read and program parse.

Second, know Json.

2.1 Json structure

A common Json format is a collection of name / value pairs, where values can be objects, lists, dictionaries, strings, and so on. such as

Backup_data = {"back_to_host": "dbbk0"

"ip_address": "10.10.20.3"

"host_name": "rac4"

"port": 3306}

2.2 using Json

The serialization and deserialization of the Json module of Python are encoded and decoded, respectively. These two processes involve two different sets of functions.

Encoding converts an Python object encoding to a Json string, json.dumps (data) / json.dump (data,file_handler)

Decoding converts a Json format string into a Python object, json.loads (data) / json.load (file_handler)

To use the Json module to do relevant operations in python, you must first import:

Import Json

2.3 main function

The main coding functions are json.dumps (data) / json.dump (data,file_handler).

The argument to json.dumps () is to convert the python object to a string, such as an object serialized with json.dumps, json_dumps=json.dumps ({'a 'json_dumps=': 1}), json_dumps=' {"b": 2, "a": 1}

Json.dump is written to a file after serializing the built-in type into a json object.

The decoding function is mainly composed of json.loads (data) / json.load (file_handler)

The parameter of json.loads is the memory object, which decodes the Json format string into a Python object, json_loads=json.loads (d_json) # {b ": 2," a ": 1}, and deserializes it to dict using load.

The parameters of json.load () are for file handles, for example, there is a local file / tmp/test.json json_load=json.load (open ('/ tmp/test.json'))

The specific cases are as follows:

In [3]: data= {"back_to_host": "rac1"

...: "ip_address": "10.215.20.3"

: "host_name": "rac3"

...: "port": 3306}

In [7]: json_str=json.dumps (data)

In [8]: print json_str

{"ip_address": "10.215.20.3", "back_to_host": "rac1", "host_name": "rac3", "port": 3306}

In [9]: json_loads=json.load (json_str)

AttributeError Traceback (most recent call last)

In ()

-> 1 json_loads=json.load (json_str)

/ System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.pyc in load (fp, encoding, cls, object_hook, parse_float, parse_int, parse_constant, object_pairs_hook, * * kw)

two hundred and eighty four

285 ""

Note that from the error message above, the json.loads parameter is a string type, not a file handle, and there is no read () attribute.

In [10]: json_loads=json.loads (json_str)

In [11]: print json_loads

{upright backtracking hostboxes: upright rac1 boxes, upright ipipads addressable: upright 10.215.20.3 boxes, upright hostworthy names: upright rac3 cycles, upright portals: 3306}

In [12]: type (json_loads)

Out [12]: dict

In [13]: type (json_str)

Out [13]: str

Using dump to write data to dump.json

In [17]: with open ('/ tmp/dump.json','w') as f:

...: json.dump (json_str,f)

...:

YangyiDBA:~ yangyi$ cat / tmp/dump.json

"{\" ip_address\ ":\" 10.10.20.3\ ",\" back_to_host\ ":\" rac1\ ",\" host_name\ ":\" rac3\ ",\" port\ ": 3306}"

YangyiDBA:~ yangyi$

Use json.load to read out dump.sjon data and assign values to data

In [18]: with open ('/ tmp/dump.json','r') as f:

...: data=json.load (f)

...:

In [19]: print data

{"ip_address": "10.10.20.3", "back_to_host": "rac1", "host_name": "rac3", "port": 3306}

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