Tiny contact book

[wak3upalex]

Tiny contact book

Summary / User Story

As a command-line learner practicing Chapter 8 (Lists & Dictionaries), I want a tiny contact book where I can add, search, update, and export contacts so I can master idiomatic list/dict operations and stable iteration patterns.

What to do?

Build a console application that stores contacts as a list of dictionaries and supports add/search/update operations plus export to a plain-text file in a deterministic order.

Step-by-step (high level):

1. Choose list[dict] as the single source of truth; fix a canonical field order.
2. Build a menu loop for add/search/update/export with input validation.
3. Use idiomatic dict ops: .get, .update, unpacking, next(..., None).
4. Ensure stable iteration: never mutate while iterating; sort consistently before showing/exporting.
5. Handle I/O errors gracefully; provide clear re-prompts.

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Requirements

• Data model

  • Keep all contacts in memory as contacts: list[dict].
  • Each contact dict uses a fixed key set and order: name (required), phone (optional), email (optional), notes (optional).
  • Normalize inputs: trim whitespace; store name in original case but use .casefold() for comparisons.

• Add

  • Prompt for fields; reject empty name.
  • Warn on potential duplicates (same normalized name + same phone or email); allow continue or cancel.
  • Append a copy of the new dict to contacts.

• Search

  • Prompt for a free-text query.
  • Case-insensitive substring match on name.
  • If query looks like digits, also match by phone; if it contains @, also match by email.
  • Display results with stable indices via enumerate(sorted_contacts).

• Update

  • Let the user select a contact by shown index from search results.
  • For each field, show current value; empty input keeps the old value.
  • Update via idiomatic patterns: contact.update({...}) or {**contact, **changes}.
  • Do not mutate the list while iterating it. If needed, iterate over a shallow copy or update by index.

• Export

  • Export to a text file (default contacts.txt).
  • Use a deterministic, stable order: sorted(contacts, key=lambda c: c["name"].casefold()).
  • Each line follows fixed field order: Name | Phone | Email | Notes (missing fields shown as -).
  • Handle I/O errors with a friendly message (e.g., permission denied, invalid path) and return to the menu.

• List (optional but recommended)

  • List all contacts using the same deterministic sort and rendering as export.

• UX

  • Main loop menu: [A]dd, [S]earch, [U]pdate, [E]xport, [Q]uit.
  • Validate menu choices; re-prompt on invalid inputs.
  • Keep prompts short; echo what changed after updates.

• Tech constraints

  • Single file main.py, no external dependencies.
  • Python 3.10+ (pattern matching optional, not required).

Acceptance Criteria

• Data structure is a list of dicts; exports use the fixed field order and are sorted case-insensitively by name.
• Add: Given a valid new contact, it appears in memory and in the next export.
• Search: Query "ann" returns "Ann" and "Joanne"; digit-only queries match phone; queries containing @ match email.
• Update: Selecting a contact by shown index and entering a new phone updates only phone; pressing Enter for email leaves it unchanged.
• Export: Produces contacts.txt with deterministic lines; attempting to export to a read-only location prints a clear error and the app continues running.
• Input validation: Empty name is rejected with a friendly message; invalid menu choice or index re-prompts without crashing.
• Iteration safety: No crashes from modifying the list while iterating (covered by tests and manual checks).

(based on materials of Learning Python by Mark Lutz — Chapter 8, Lists & Dictionaries)

Example of action

$ python3 main.py
[Tiny Contact Book]
A) Add  S) Search  U) Update  E) Export  Q) Quit
Choose: A
Name: Ann Li
Phone (optional): 555-1234
Email (optional): ann@example.com
Notes (optional): teammate
Added: Ann Li

A) Add  S) Search  U) Update  E) Export  Q) Quit
Choose: S
Query: ann
[0] Ann Li | 555-1234 | ann@example.com | teammate
1 result(s)

A) Add  S) Search  U) Update  E) Export  Q) Quit
Choose: U
Search first. Query: ann
[0] Ann Li | 555-1234 | ann@example.com | teammate
Select index: 0
Phone [555-1234]: 555-5678
Email [ann@example.com]:
Notes [teammate]: design lead
Updated: Ann Li

A) Add  S) Search  U) Update  E) Export  Q) Quit
Choose: E
File path [contacts.txt]:
Exported 1 contact(s) to contacts.txt

Example contacts.txt:

Ann Li | 555-5678 | ann@example.com | design lead

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What to do in future?

• Persistence: load/save JSON or CSV; import from .csv.

• Unique IDs: add id per contact to disambiguate identical names.

• Delete & Undo: safe deletion and simple undo of last change.

• Sorting & View: allow sort by name/email; pretty table view.

• Search++: AND/OR filters, tag support via tags: list[str].

• Tests (pytest):

  • Add contact and assert presence in memory.
  • Search "ann" matches expected names; digit query matches phone.
  • Update keeps fields on empty input and changes targeted field.
  • Export yields deterministic lines given a known dataset.
  • Export error path (mock failure or invalid path) handled gracefully.