{"id":129386,"date":"2022-11-01T10:49:11","date_gmt":"2022-11-01T10:49:11","guid":{"rendered":"https:\/\/blog.finxter.com\/?p=852705"},"modified":"2022-11-01T10:49:11","modified_gmt":"2022-11-01T10:49:11","slug":"python-create-json-file","status":"publish","type":"post","link":"https:\/\/sickgaming.net\/blog\/2022\/11\/01\/python-create-json-file\/","title":{"rendered":"Python Create JSON File"},"content":{"rendered":"\n
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5\/5 – (1 vote) <\/div>\n<\/div>\n

Problem Formulation and Solution Overview<\/h2>\n

This article focuses on working with a JSON file. JSON<\/a> is an acronym for JavaScript Object Notation. This is a flat-text file formatted based on JavaScript (JS) Syntax. <\/p>\n

This file is most commonly noted for its ability to transmit data to\/from web applications, such as sending\/receiving data from a Server\/Client to display or retrieve said data.<\/p>\n

The JSON file structure has keys and values similar to a Python Dictionary<\/a>.<\/p>\n

This structure can contain strings, boolean, integers, floats, lists<\/a>, and much more. This file structure can be as simple or complex as needed.<\/p>\n

This article works with Rivers Clothing, a new start-up. They have hired their first three (3) employees. This employee data is displayed as a List of Dictionaries<\/a>.<\/p>\n

emps = {\"hires\": [{\"ID\": 324, \"name\": \"Alex Smith\", \"title\": \"Manager\"}, {\"ID\": 325, \"name\": \"Micah Jones\", \"title\": \"Designer\"}, {\"ID\": 326, \"name\": \"Sam Quinn\", \"title\": \"Coder\"}]}<\/pre>\n
\n
\"\ud83d\udcac\" Question<\/strong>: How would we write code to create and work with a JSON File<\/em>?<\/em><\/p>\n
    \n
  1. Python Create JSON File if Not Exists<\/li>\n
  2. Python Create JSON String from List of Dictionaries<\/a><\/li>\n
  3. Python Create JSON File and Write Data<\/li>\n
  4. Python Read JSON File<\/li>\n
  5. Python Access JSON Elements<\/li>\n
  6. Python Delete JSON Elements<\/li>\n<\/ol>\n
    \n
    Python Create JSON File if Not Exists<\/h2>\n
    This example creates an empty JSON file if one does not exist in the current working directory.<\/p>\n
    import os filename = 'employees.json'\nisFile = os.path.isfile(filename) if (not isFile): with open(filename, 'w') as fp: pass\nelse: print(f'The {filename} file exists.')<\/pre>\n
    The first line in the above code snippet imports Python’s built-in os<\/code><\/a> library. This allows access to and manipulation of files and folders. <\/p>\n
    The following line declares the JSON file name, employees.json<\/code> and saves it to the variable filename<\/code>.<\/p>\n
    The next line calls the os.path.isfile()<\/code><\/a> function and passes it one (1) argument, filename<\/code>. This function checks the current directory for the existence of the employees.json<\/code> file<\/p>\n
    The first time this code runs, and this file is not <\/strong>found (isFile <\/code>is False), an empty file is created and placed into the current working directory. <\/p>\n
    \"\ud83d\udca1\"Note<\/strong>: The pass<\/a><\/code> statement is a placeholder code and does nothing when executed. This is used here so a file is created, and nothing else occurs.<\/p>\n
    If this code is rerun or the file exists, the following message is output to the terminal.<\/p>\n
    \n\n\n\n
    The employees.json<\/code> file exists.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n
    To create this file in a sub-folder, you would modify the code as follows:<\/p>\n
    import os filename = 'files\\\\employees.json'\nisFile = os.path.isfile(filename) if (not isFile): with open(filename, 'w') as fp: pass\nelse: print(f'The {filename} file exists.')<\/pre>\n
    When this code runs, the files folder is checked for the existence of the employees<\/code>.json<\/code> file.<\/p>\n
    \"YouTube<\/a>
    <\/figcaption><\/figure>\n
    \n
    Python Create JSON String from List of Dictionaries<\/h2>\n
    This example creates a JSON string from a List of Dictionaries<\/a>.<\/p>\n
    import json emps = {\"hires\" :[{\"empID\": \"RC-3243\", \"name\": \"Alexa Smith\", \"title\": \"Manager\"}, {\"empID\": \"RC-3244\", \"name\": \"Micah Jones\", \"title\": \"Designer\"}, {\"empID\": \"RC-3245\", \"name\": \"Sam Quinn\", \"title\": \"Coder\"}]} json_str = json.dumps(emps, indent=4)\nprint(json_str)<\/pre>\n
    The above code snippet imports the json<\/code><\/a> library. This library allows access to JSON functions. <\/p>\n
    The following three (3) lines construct a List of Dictionaries<\/a> containing data for the new hires. The results save to emps<\/code>.<\/p>\n
    Next, json.dumps()<\/a> <\/code>is called and passed two (2) arguments: a List of Dictionaries<\/a>, emps<\/code>, and for formatting, spaces to indent. The results save to json_str<\/code> and output to the terminal.<\/p>\n
    \n\n\n\n
    {
    \"hires\": [
     {
     \"ID\": 3243,
     \"name\": \"Alexa Smith\",
     \"title\": \"Manager\"
     },
     {
     \"ID\": 3244,
     \"name\": \"Micah Jones\",
     \"title\": \"Designer\"
     },
     {
     \"ID\": 3245,
     \"name\": \"Sam Quinn\",
     \"title\": \"Coder\"
     } 
     ]
    }<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n
    \"\ud83d\udca1\"Note<\/strong>: The json.dumps()<\/a> <\/code>function formats the JSON string. To write this to a file, json.dump()<\/a><\/code> is used.<\/p>\n
    \n
    Python Create JSON File and Write Data<\/h2>\n
    This example writes a List of Dictionaries<\/a> to a JSON file.<\/p>\n
    import os\nimport json filename = 'employees.json'\nisFile = os.path.isfile(filename) emps = {\"hires\" :[{\"ID\": 3243, \"name\": \"Alexa Smith\", \"title\": \"Manager\"}, {\"ID\": 3244, \"name\": \"Micah Jones\", \"title\": \"Designer\"}, {\"ID\": 3245, \"name\": \"Sam Quinn\", \"title\": \"Coder\"}]} if (not isFile): with open(filename, 'w') as fp: json.dump(emps, fp, indent=4)\nelse: print(f'An error occurred writing to {filename}.') <\/pre>\n
    The above code snippet adds the two (2) highlighted lines to write the formatted JSON string to the employees.json<\/code> file. <\/p>\n
    The contents of this file is as follows:<\/p>\n
    \n\n\n\n
    {
    \"hires\": [
     {
     \"ID\": 3243,
     \"name\": \"Alexa Smith\",
     \"title\": \"Manager\"
     },
     {
     \"ID\": 3244,
     \"name\": \"Micah Jones\",
     \"title\": \"Designer\"
     },
     {
     \"ID\": 3245,
     \"name\": \"Sam Quinn\",
     \"title\": \"Coder\"
     } 
     ]
    }<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n
    \n
     Python Read JSON File<\/h2>\n
    In this example, the JSON file saved earlier is read back in.<\/p>\n
    import os\nimport json filename = 'employees.json'\njson_str = '' with open(filename , 'r') as fp: for l in fp: l.replace('\\n', '') json_str += l print(json_str)<\/pre>\n
    This code snippet opens, reads the employees.json<\/code> file and saves it to json_str<\/code>. Upon each iteration, any additional newline (\\n<\/code>) characters are removed using the replace()<\/a> <\/code>function. <\/p>\n
    Once all lines have been read, the contents of json_str<\/code> is output to the terminal and is the same as indicated above.<\/p>\n
    \"YouTube<\/a>
    <\/figcaption><\/figure>\n
    \n
    Python Access JSON Elements<\/h2>\n
    This example reads in the previously saved JSON file and accesses the ID element from each hire.<\/p>\n
    import os\nimport json filename = 'employees.json'\njson_str = '' with open(filename , 'r') as fp: for l in fp: l.replace('\\n', '') json_str += l all_emps = json.loads(json_str)\nalexa_id = all_emps['hires'][0]['ID']\nsam_id = all_emps['hires'][2]['ID']\nprint(alexa_id, sam_id)<\/pre>\n
    As outlined earlier in this article, the employees.json<\/code> file is read in, parsed and saved to json_str<\/code>.<\/p>\n
    Then, json_str <\/code>is loaded using json_loads()<\/code><\/a> and passed one (1) argument, the json_str<\/code> created above. This gives us access to the elements.<\/p>\n
    The following lines access the Employee IDs for Alexa and Micah and outputs same to the terminal.<\/p>\n
    \n\n\n\n
     3243 3245<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n
    To iterate and display the ID<\/code> and name<\/code> for each new hire<\/code>, run the following code:<\/p>\n
    import os\nimport json filename = 'employees.json'\njson_str = '' with open(filename , 'r') as fp: for l in fp: l.replace('\\n', '') json_str += l all_emps = json.loads(json_str) for item in all_emps['hires']: print(item['ID'], item['name'])<\/pre>\n
    Another option is to use List Comprehension<\/a> to retrieve the data:<\/p>\n
    results = [item['ID'] for item in all_emps['hires']]\nprint(results)<\/pre>\n
    \"YouTube<\/a>
    <\/figcaption><\/figure>\n
    \n
    Python Delete Elements<\/h2>\n
    This example reads in the previously saved JSON file and deletes the new hire, Micah Jones.<\/p>\n
    import os\nimport json filename = 'employees.json'\njson_str = '' with open(filename , 'r') as fp: for l in fp: l.replace('\\n', '') json_str += l all_emps = json.loads(json_str)\nidx = 0 for item in all_emps['hires']: if idx == 1: del all_emps['hires'][idx] idx += 1\nprint(all_emps)<\/pre>\n
    \n
    Summary<\/h2>\n
    We hope you enjoyed this article about converting a List of Dictionaries<\/a> to JSON and everything in between!<\/p>\n
    Good Luck & Happy Coding!<\/p>\n
    \n
    Programmer Humor – Blockchain<\/h2>\n
    \n
    \"\"
    “Blockchains are like grappling hooks, in that it’s extremely cool when you encounter a problem for which they’re the right solution, but it happens way too rarely in real life.”<\/em> source <\/strong> – xkcd<\/a><\/figcaption><\/figure>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
    5\/5 – (1 vote) Problem Formulation and Solution Overview This article focuses on working with a JSON file. JSON is an acronym for JavaScript Object Notation. This is a flat-text file formatted based on JavaScript (JS) Syntax. This file is most commonly noted for its ability to transmit data to\/from web applications, such as sending\/receiving […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[857],"tags":[73,468,528],"class_list":["post-129386","post","type-post","status-publish","format-standard","hentry","category-python-tut","tag-programming","tag-python","tag-tutorial"],"_links":{"self":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/posts\/129386","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/comments?post=129386"}],"version-history":[{"count":0,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/posts\/129386\/revisions"}],"wp:attachment":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/media?parent=129386"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/categories?post=129386"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/tags?post=129386"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}