general.json

{
  "category_name": "General",
  "todos": [
    {
      "task": "My TODO Task",
      "due_on": null,
      "status": "pending",
      "description": null
    },
    {
      "task": "My TODO Task",
      "due_on": "2018-03-05",
      "status": "pending",
      "description": "Much description, wow"
    }
  ]
}

pathlib_testing.py

"""

    def __init__(self, base_todos_path, create_dir=True):
        self.base_todos_path = base_todos_path
        self.path = Path(self.base_todos_path)
        # continue here
        if not self.path.exists():
            # create the directory
            self.path.mkdir()

    def list(self, status=STATUS_ALL, category=CATEGORY_GENERAL):
        json_files = self.path.glob('*')

"""

import json
from pathlib import Path

{
    'Programming': [{
        'task': 'Practice Pathlib',
        'description': 'Investigate Pathlib and file creation',
        'due_on': '2018-03-25',
        'status': 'pending'
    }, {
        'task': 'Finish rmotrgram',
        'description': 'Finish before class to start reviewing',
        'due_on': '2018-03-21',
        'status': 'done'
    }],
    'Reviews': [{
        'task': 'Review rmotrgram',
        'description': 'Finish review before weekend',
        'due_on': '2018-03-28',
        'status': 'pending'
    }]
}

p = Path('todos')
json_files = p.glob('*.json')
result = {}

for json_file in json_files:
    with json_file.open() as fp:
        todo = json.loads(fp.read())
        print(todo['category_name'])

reviews.json

{
  "category_name": "Reviews",
  "todos": [
    {
      "task": "First review todo",
      "due_on": null,
      "status": "pending",
      "description": null
    }
  ]
}

todos.py

import json
from pathlib import Path
from datetime import date


class TodoManager(object):
    STATUS_ALL = 'all'
    STATUS_DONE = 'done'
    STATUS_PENDING = 'pending'
    CATEGORY_GENERAL = 'general'

    def __init__(self, base_todos_path, create_dir=True):
        self.base_todos_path = base_todos_path
        self.path = Path(self.base_todos_path)
        # continue here
        if self.path.exists() and self.path.is_file():
            raise ValueError("There's a file with that name")

        if not self.path.exists():
            # create the directory
            self.path.mkdir()

    def list(self, status=STATUS_ALL, category=CATEGORY_GENERAL):
        json_files = self.path.glob('*.json')
        result = {}
        
        for json_file in json_files:
            with json_file.open() as fp:
                
                todo_file_doc = json.loads(fp.read())
                cat_name = todo_file_doc['category_name']
                todos = todo_file_doc['todos']
                result[cat_name] = []
                
                for todo in todos:
                    if todo['status'] == status:
                        result[cat_name].append(todo)
                    
        return result

    def new(self, task, category=CATEGORY_GENERAL, description=None,
            due_on=None):

        if due_on:
            if type(due_on) == date:
                due_on = due_on.isoformat()
            elif type(due_on) == str:
                # all good
                pass
            else:
                raise ValueError('Invalid due_on type. Must be date or str')

        # continue here
        # if file doesn't exist:
        # create file with category name
        
        # add the todo
        todo_path = self.path / (category + '.json')
        
        if not todo_path.exists():
            # create it...
            empty_document = {
                'category_name': category.title(),
                'todos': []
            }
            with todo_path.open('w') as fp:
                json_document = json.dumps(empty_document)
                fp.write(json_document)

        # S2
        with todo_path.open() as fp:
            todos_doc = json.loads(fp.read())

        todos_doc['todos'].append({
          "task": task,
          "due_on": due_on,
          "status": "pending",
          "description": description
        })

        with todo_path.open('w') as fp:
            json_document = json.dumps(todos_doc)
            fp.write(json_document)