Mastering File Handling Part 2: Managing Data Records with Pickle

This is a PyQt5-based application for managing exercise data, such as logging, storing, and viewing exercise details like type, date, distance, duration, and energy burned. Below are the major functionalities and their explanations:

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Major Functions

1. populate_exercise_types()

• Purpose: Initializes and updates the dropdown menus (comboBox1 and comboBox2) with exercise types.
• Working:
  • Ensures a directory and file (typesCourse.txt) exist.
  • If the file doesn't exist, creates it with default exercise types like "Walking," "Cycling," etc.
  • Reads the exercise types from the file and populates the dropdowns for adding and filtering exercises.

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2. add_exercise_entry()

• Purpose: Collects exercise data from the input fields and stores it in a binary file (Exercice.dat).
• Working:
  • Validates user inputs for type, date, distance, and duration.
  • Determines the type of exercise (new or selected).
  • Converts distance and duration into energy burned using a fixed formula.
  • Saves the exercise entry in the binary file:
    • If the file doesn't exist, creates it.
    • If it exists, appends the new data to existing entries.
  • Adds new exercise types to typesCourse.txt if applicable.
  • Refreshes the dropdown menus and clears input fields after successful addition.

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3. clear_input_fields()

• Purpose: Clears all the input fields in the form.
• Working: Resets text fields (newType, date1, distance1, duration1) to empty strings.

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4. display_overview()

• Purpose: Displays a summary of exercise sessions and detailed records filtered by type.
• Working:
  • Reads exercise records from the binary file.
  • Filters records based on the selected type (comboBox2), or displays all if "All" is chosen.
  • Calculates:
    • Total duration (in seconds).
    • Total energy burned.
    • Number of sessions.
  • Updates the overview table with these totals.
  • Populates a detailed table with individual records, showing their type, date, distance, duration, and energy burned.

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5. time_to_seconds(duration)

• Purpose: Converts a time string (formatted as hh:mm:ss) into total seconds.
• Working: Splits the duration string into hours, minutes, and seconds, and computes the total seconds.

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Overall Flow

1. Initialization:

   • The UI is loaded using loadUi().
   • Dropdown menus are populated using populate_exercise_types().

2. Adding an Exercise:

   • Users fill in the exercise type, date, distance, and duration.
   • The app calculates energy burned and saves the data.

3. Viewing Exercise Data:

   • Users can filter by exercise type or view all records.
   • Total sessions, duration, and energy are displayed in summary.

4. Data Handling:

   • The application uses text files (typesCourse.txt) for types and binary files (Exercice.dat) for data storage.
   • Uses the pickle module for efficient serialization and deserialization of exercise data.

This code is designed with error handling for file I/O and input validation to ensure robustness. It also provides user feedback via message boxes for success or error scenarios.

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TV Channel Application

I have used these widgets for the formation of the above GUI:

Label Widgets

• First label is used to display New Channel.
• Then similarly I have used numerous label widgets to display the instruction and hints for the user.

Input Fields

• First input field is to get the name of the channel.
• The next input fields are used to get input from the user for frequency, SR FAC and cryptage.

Button

• I have used three pushButton.
• One button is Add.
• The other button is Cancel.
• The last button is Find.

Table Widget

• I have used a tableWidget to display the data in the form of the rows and column.

ComboBox

• I have used two comboBox to select the category of the channel.

Setting Custom Names

• I have set specific name for each widget used in this user interface to manage the working and functionality in the code.

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I have used CSS to style the background and colour of the labels.

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This is a PyQt5 based application for managing channel information such as frequency, polarization, and category. It uses pickle to handle persistent storage in binary files and categories.txt for predefined categories. Below is the explanation of major functionalities and logic:

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Major Functions

1. filList

• Purpose: Populates the two dropdown menus (comboBox1 and comboBox2) with categories listed in the categories.txt file.
• Logic:
  • Opens categories.txt and reads all lines into a list.
  • Clears existing dropdown options and repopulates them with the categories.
  • Adds a default "Select a category" option at the beginning of both dropdowns.
• Error Handling: Shows an error message if categories.txt is not found or if there is an issue reading the file.

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2. validate_input

• Purpose: Ensures that all form inputs are valid before allowing the user to add a channel.
• Logic:
  • Checks if mandatory fields like channel name, frequency, polarization, SR FAC, and category are properly filled.
  • Ensures frequency is an integer between 10,000 and 20,000 and SR FAC is a 5-digit integer.
  • Validates that a polarization option is selected (either Vertical V or Horizontal H).
• Output: Returns True if all validations pass; otherwise, shows warning messages and returns False.

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3. get_selected_polarization

• Purpose: Determines which polarization (V or H) is selected from the radio buttons.
• Logic:
  • Returns "V" if the corresponding radio button is checked.
  • Returns "H" if the other button is checked.
  • Returns None if neither is selected.

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4. add_channel

• Purpose: Adds a new channel to the listChannels.dat file.
• Logic:
  • Validates form inputs using validate_input.
  • Gathers data from the form fields and creates a dictionary to represent the channel.
  • Writes the channel dictionary to listChannels.dat using pickle. If the file does not exist, it creates a new one.
  • Clears the form fields after successfully adding the channel.
• Error Handling: Displays appropriate messages if there are issues with file operations.

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5. clear_form

• Purpose: Resets all input fields to their default state.
• Logic:
  • Clears text inputs, resets radio buttons, and sets dropdowns to the default "Select a category" option.

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6. find_channels

• Purpose: Filters and displays channels based on search criteria (name or category).
• Logic:
  • Reads all channel records from listChannels.dat using pickle.
  • Filters the records:
    • Matches channel names containing the search term (case-insensitive) if provided.
    • Matches the selected category if it’s not "Select a category."
  • Updates the table widget (overalltable) to display the filtered results.
• Error Handling: Displays messages if no channels are found or if file operations fail.

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File Handling

1. categories.txt:

   • Stores predefined channel categories.
   • Populated into the dropdown menus for selection.

2. listChannels.dat:

   • A binary file storing the list of channels as serialized dictionaries using pickle.

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Flow of the Application

1. The GUI is loaded from the channel.ui file, and dropdowns are populated using filList.
2. Users can:
   • Add new channels via add_channel:
     • Fill in details (name, frequency, polarization, etc.).
     • Validate inputs and save the channel to the file.
   • Search for channels via find_channels:
     • Provide a partial name or select a category to filter records.
     • View results in a table.
   • Reset the form via clear_form.

This design makes the application intuitive for managing channel data with effective validation and file handling.

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Developer Sheets Application

I have used these widgets for the formation of the above GUI:

Label Widgets

• First label is used to display Developer Sheets.
• Then similarly I have used numerous label widgets to display the instruction and hints for the user.

Input Fields

• I have used 2 input fields.
• First input field is to get the name and surname of the user.
• The next input field is to get the email address.

Button

• I have used three pushButton.
• One button is Save.
• The other button is Delete.
• The last button is Close.

Table Widget

• I have used a tableWidget to display the data in the form of the rows and column.

ComboBox

• I have used a comboBox to select the first language.

Setting Custom Names

• I have set specific name for each widget used in this user interface to manage the working and functionality in the code.

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I have used CSS to style the background and colour of the labels.

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The app manages records of developers, including their personal details, programming preferences, and languages known. Here's a detailed explanation:

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Purpose

• Manage Developer Records: Allows users to input and save developers' details, display existing records, and reset forms.
• Persist Data: Stores the data in a binary file (sheet.dat) using the pickle module.
• Interactive GUI: Features user-friendly interfaces for adding and viewing records.

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Major Functions

Initialization and Setup (__init__)

• UI Loading:
  • The sheet.ui file defines the graphical user interface. It's loaded using loadUi.
• Button Connections:
  • save_button: Triggers the save_record function.
  • clear_button: Resets the form via clear_form.
  • close_button: Closes the application via close_application.
• Default Image: Loads an image (side_image.png) into the image_label widget, scaled to fit the label size.
• Load Records on Start: Reads previously saved records from sheet.dat and displays them in a table widget.

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Image Handling

• load_default_image: Displays a default image (side_image.png) in the GUI.
  • Uses QPixmap to load the image.
  • Ensures the image fits the image_label widget precisely using scaled.

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Input Validation

• validate_input: Ensures all required fields are correctly filled:
  • Name: Must not be empty.
  • Email: Must contain an @ symbol.
  • Civility: A radio button (e.g., "Sr.", "Miss.", "Madam") must be selected.
  • First Language: A dropdown menu must have a valid selection.
• Radio Button Selection (get_selected_civility): Checks which civility is selected.
• Programming Language Selection (get_selected_languages): Retrieves all programming languages marked via checkboxes.

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Saving Records

• save_record:
  • Data Collection: Gathers inputs from form fields.
  • Validation: Ensures inputs are valid using validate_input.
  • Record Creation: Constructs a dictionary for the developer record.
  • File Handling:
    • If the file (sheet.dat) exists, it appends the new record to the existing list.
    • If the file doesn't exist, it creates a new file and saves the record.
  • UI Feedback: Updates the action_label and displays a success message.
  • Error Handling: Catches and reports errors using a QMessageBox.

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Clearing the Form

• clear_form: Resets all form fields to default values:
  • Text fields (name_field, mail_field) are cleared.
  • Civility (radioSr) is reset to "Sr.".
  • Checkboxes are unchecked.
  • Action label (action_label) is cleared.

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Loading Records

• load_records:
  • Reads records from sheet.dat using pickle.
  • Populates the tableWidgetA with the data:
    • Civility, Name, Email, First Language, and Programming Languages are displayed.
  • If the file is not found, the table is shown as empty.

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How the Application Works

1. Start Up:

   • The UI is loaded.
   • Existing records are displayed in the table widget.
   • A default image is loaded into the image label.

2. Adding a Record:

   • Fill in the form with details like name, email, civility, first language, and programming languages.
   • Click "Save" to validate inputs and save the record to sheet.dat.

3. Viewing Records:

   • Saved records are displayed in the table widget.

4. Clearing the Form:

   • Click "Clear" to reset all fields to default.

5. Closing the App:

   • Click "Close" to exit.

This app combines input validation, file handling, and GUI features to create an efficient record management system for developers.

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I would like to invite @heriadi, @chant and @jospeha to join this contest.

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