How do I write JSON data to a file

Question

I have JSON data stored in the variable data   I want to write this to a text file for testing so I don t have to grab the data from the server each time   Currently  I am trying this   obj   open  data txt    wb   obj write data  obj close   And I am receiving this error       TypeError  must be string or buffer  not dict   How to fix this

User · Answer

I don t have enough reputation to add in comments  so I just write some of my findings of this annoying TypeError here   Basically  I think it s a bug in the json dump   function in Python 2 only - It can t dump a Python  dictionary   list  data containing non-ASCII characters  even you open the file with the encoding    utf-8  parameter   i e  No matter what you do   But  json dumps   works on both Python 2 and 3   To illustrate this  following up phihag s answer  the code in his answer breaks in Python 2 with exception TypeError  must be unicode  not str  if data contains non-ASCII characters   Python 2 7 6  Debian    import json data    u  u0430 u0431 u0432 u0433 u0434   1    u         1  with open  data txt    w   as outfile      json dump data  outfile    It however works fine in Python 3

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Read and write JSON files with Python 2 3  works with unicode    - - coding  utf-8 - - import json    Make it work for Python 2 3 and with Unicode import io try      to unicode   unicode except NameError      to unicode   str    Define data data     a list    1  42  3 141  1337   help   u                 a string    bla            another dict     foo    bar                             key    value                             the answer   42      Write JSON file with io open  data json    w   encoding  utf8   as outfile      str    json dumps data                        indent 4  sort keys True                        separators              ensure ascii False      outfile write to unicode str       Read JSON file with open  data json   as data file      data loaded   json load data file   print data    data loaded    Explanation of the parameters of json dump    indent  Use 4 spaces to indent each entry  e g  when a new dict is started  otherwise all will be in one line   sort keys  sort the keys of dictionaries  This is useful if you want to compare json files with a diff tool   put them under version control  separators  To prevent Python from adding trailing whitespaces   With a package  Have a look at my utility package mpu for a super simple and easy to remember one   import mpu io data   mpu io read  example json   mpu io write  example json   data    Created JSON file         a list            1          42          3 141          1337           help                             a string   bla        another dict             foo   bar            key   value            the answer  42           Common file endings   json  Alternatives   CSV  Super simple format  read  amp  write  JSON  Nice for writing human-readable data  VERY commonly used  read  amp  write  YAML  YAML is a superset of JSON  but easier to read  read  amp  write  comparison of JSON and YAML  pickle  A Python serialization format  read  amp  write  MessagePack  Python package   More compact representation  read  amp  write  HDF5  Python package   Nice for matrices  read  amp  write  XML  exists too  sigh   read  amp  write    For your application  the following might be important    Support by other programming languages Reading   writing performance Compactness  file size    See also  Comparison of data serialization formats  In case you are rather looking for a way to make configuration files  you might want to read my short article Configuration files in Python

User · Answer

You forgot the actual JSON part - data is a dictionary and not yet JSON-encoded  Write it like this for maximum compatibility  Python 2 and 3    import json with open  data json    w   as f      json dump data  f    On a modern system  i e  Python 3 and UTF-8 support   you can write a nicer file with  import json with open  data json    w   encoding  utf-8   as f      json dump data  f  ensure ascii False  indent 4

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I would answer with slight modification with aforementioned answers and that is to write a prettified JSON file which human eyes can read better  For this  pass sort keys as True and indent with 4 space characters and you are good to go  Also take care of ensuring that the ascii codes will not be written in your JSON file   with open  data txt    w   as outfile       json dump jsonData  outfile  sort keys   True  indent   4                 ensure ascii   False

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if you are trying to write a pandas dataframe into a file using a json format i d recommend this  destination  filepath  saveFile   open destination   w   saveFile write df to json    saveFile close

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Write a data in file using JSON use json dump   or json dumps   used  write like this to store data in file   import json data    1 2 3 4 5  with open  no txt    w   as txtfile      json dump data  txtfile    this example in list is store to a file

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The accepted answer is fine  However  I ran into  is not json serializable  error using that   Here s how I fixed it with open  file-name json    w   as output   output write str response    Although it is not a good fix as the json file it creates will not have double quotes  however it is great if you are looking for quick and dirty

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To get utf8-encoded file as opposed to ascii-encoded in the accepted answer for Python 2 use   import io  json with io open  data txt    w   encoding  utf-8   as f    f write json dumps data  ensure ascii False     The code is simpler in Python 3   import json with open  data txt    w   as f    json dump data  f  ensure ascii False    On Windows  the encoding  utf-8  argument to open is still necessary   To avoid storing an encoded copy of the data in memory  result of dumps  and to output utf8-encoded bytestrings in both Python 2 and 3  use   import json  codecs with open  data txt    wb   as f      json dump data  codecs getwriter  utf-8   f   ensure ascii False    The codecs getwriter call is redundant in Python 3 but required for Python 2    Readability and size   The use of ensure ascii False gives better readability and smaller size    gt  gt  gt  json dumps   price       10       price      u20ac10     gt  gt  gt  json dumps   price       10    ensure ascii False     price       10      gt  gt  gt  len json dumps           1    37  gt  gt  gt  len json dumps           1   ensure ascii False  encode  utf8    17   Further improve readability by adding flags indent 4  sort keys True  as suggested by dinos66  to arguments of dump or dumps  This way you ll get a nicely indented sorted structure in the json file at the cost of a slightly larger file size

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Writing JSON to a File  import json  data      data  people        data  people   append        name    Scott        website    stackabuse com        from    Nebraska     data  people   append        name    Larry        website    google com        from    Michigan     data  people   append        name    Tim        website    apple com        from    Alabama      with open  data txt    w   as outfile      json dump data  outfile    Reading JSON from a File  import json  with open  data txt   as json file      data   json load json file      for p in data  people            print  Name      p  name            print  Website      p  website            print  From      p  from            print

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To write the JSON with indentation   pretty print    import json  outfile   open  data json   json dump data  outfile  indent 4    Also  if you need to debug improperly formatted JSON  and want a helpful error message  use import simplejson library  instead of import json  functions should be the same

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All previous answers are correct here is a very simple example       usr bin env python import json  def write json          create a dictionary       student data     students           create a list     data holder   student data  students         just a counter     counter   0      loop through if you have multiple items                while counter  lt  3          data holder append   id  counter           data holder append   room  counter           counter    1          write the file             file path   tmp student data json      with open file path   w   as outfile          print  writing file to    file path            HERE IS WHERE THE MAGIC HAPPENS          json dump student data  outfile      outfile close            print  done    write json

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json dump data  open  data txt    wb

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For those of you who are trying to dump greek or other  exotic  languages such as me but are also having problems  unicode errors  with weird characters such as the peace symbol   u262E  or others which are often contained in json formated data such as Twitter s  the solution could be as follows  sort keys is obviously optional    import codecs  json with codecs open  data json    w    utf8   as f       f write json dumps data  sort keys   True  ensure ascii False

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The JSON data can be written to a file as follows   hist1      val loss    0 5139984398465246    val acc    0 8002029867684085    loss    0 593220705309384    acc    0 7687131817929321      val loss    0 46456472964199463    val acc    0 8173602046780344    loss    0 4932038113037539    acc    0 8063946213802453      Write to a file   with open  text1 json    w   as f       json dump hist1  f

[python] How do I write JSON data to a file?

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