![Low-Level Design: Polling System](https://img.php.cn/upload/article/000/000/000/172501437254013.jpg)
Jadual Kandungan
- Pernyataan Masalah
- Andaian
- Keperluan
- Buat Undian
- Urus Pungutan Suara
- Undi dalam Pungutan Suara
- Lihat Keputusan Pungutan Suara
- Data Undian
- Butiran Pelaksanaan
- Fungsi/Kaedah
- Buat Tinjauan pendapat
- Kemas kini Tinjauan pendapat
- Padamkan Tinjauan pendapat
- Undi Dalam Tinjauan pendapat
- Lihat Keputusan Pungutan Suara
- Model Data
- Butiran Pelaksanaan
- KOD
Pernyataan Masalah
Anda dikehendaki mereka bentuk dan melaksanakan sistem pengundian dalam talian. Sistem harus membenarkan pengguna membuat, mengurus dan mengambil bahagian dalam tinjauan pendapat. Setiap tinjauan pendapat terdiri daripada satu soalan dan berbilang pilihan untuk jawapan. Pengguna boleh mengundi pada tinjauan pendapat dan melihat keputusan.
Andaian:
- Kami menggunakan pelaksanaan berasaskan Kelas
- Kami tidak menggunakan Pangkalan Data tambahan untuk menyimpan maklumat ini
- Memandangkan DB & pelayan tidak terlibat, tiada REST API
- pendekatan Tahap Rendah yang ringkas pada Sistem Pengundian
Keperluan
Cipta Tinjauan:
- Pengguna sepatutnya boleh membuat tinjauan pendapat baharu dengan soalan dan berbilang pilihan jawapan.
- Setiap tinjauan pendapat mesti mempunyai pengecam unik, soalan, senarai pilihan dan cap masa penciptaan.
Urus Tinjauan:
- Pengguna seharusnya boleh mengemas kini soalan atau pilihan tinjauan pendapat sedia ada.
- Pengguna sepatutnya boleh memadamkan tinjauan pendapat.
Undi dalam Undian:
- Pengguna sepatutnya boleh membuang undi untuk salah satu pilihan dalam tinjauan pendapat.
- Setiap pengguna hanya boleh mengundi sekali setiap tinjauan pendapat.
Lihat Keputusan Undian:
- Pengguna seharusnya dapat melihat keputusan semasa tinjauan pendapat, termasuk bilangan undian untuk setiap pilihan.
Data Undian:
- Simpan tinjauan pendapat, pilihan dan undian dengan cara yang membolehkan perolehan semula dan kemas kini yang cekap.
- Pastikan integriti dan konsistensi data, terutamanya apabila berbilang pengguna mengundi secara serentak.
Butiran Pelaksanaan
Fungsi/Kaedah:
Buat Tinjauan Umum
buat Poll:
- Input: soalan (rentetan), pilihan (susun rentetan)
- Output: pollId (rentetan), mesej (rentetan)
- Contoh: createPoll("Apakah warna kegemaran anda?", ["Merah", "Biru", "Hijau", "Kuning"]) mengembalikan {"pollId": "123", "message" : "Tinjauan pendapat berjaya dibuat."}
Kemas kini Tinjauan
kemas kiniPoll:
- Input: pollId (rentetan), soalan (rentetan), pilihan (susun rentetan)
- Output: mesej (rentetan)
- Contoh: updatePoll("123", "Soalan dikemas kini?", ["Option1", "Option2"]) mengembalikan {"message": "Poll updated successfully."}
Padamkan Tinjauan pendapat
deletePoll:
- Input: pollId (rentetan)
- Output: mesej (rentetan)
- Contoh: deletePoll("123") mengembalikan {"message": "Tinjauan telah berjaya dipadamkan."}
Undi Dalam Tinjauan
voteInPoll:
- Input: pollId (rentetan), userId (rentetan), pilihan (rentetan)
- Output: mesej (rentetan)
- Contoh: voteInPoll("123", "user1", "Option1") mengembalikan {"message": "Berjaya mengundi."}
Lihat Keputusan Undian
lihatPollResults:
- Input: pollId (rentetan)
- Output: pollId (rentetan), soalan (rentetan), keputusan (objek dengan kunci pilihan dan nilai kiraan undi)
- Contoh: viewPollResults("123") mengembalikan {"pollId": "123", "question": "Apakah warna kegemaran anda?", "results": {"Red": 10, "Blue ": 5, "Hijau": 3, "Kuning": 2}}
Model Data
{ "pollId": "123", "question": "What is your favorite color?", "options": ["Red", "Blue", "Green", "Yellow"], "createdAt": "2024-07-11T00:00:00Z" }
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{ "pollId": "123", "userId": "user1", "option": "Red", "timestamp": "2024-07-11T01:00:00Z" }
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Butiran Pelaksanaan
Kod ini mentakrifkan sistem pengundian asas menggunakan kelas JavaScript. Ia membenarkan penciptaan, pengurusan dan pengundian dalam tinjauan pendapat. Mari pecahkan setiap bahagian kod:
1.Class Definitions
Poll Class
- Purpose:Represents an individual poll.
- Constructor Parameters:
- id: A unique identifier for the poll.
- question: The question being asked in the poll.
- options: An array of possible options that users can vote on.
- Properties:
- pollId: Stores the unique ID of the poll.
- question: Stores the poll question.
- options: Stores the array of options.
- createdAt: Stores the creation date and time of the poll.
Vote Class
- Purpose:Represents an individual vote cast by a user.
- Constructor Parameters:
- pollId: The ID of the poll the vote is associated with.
- userId: The ID of the user who cast the vote.
- option: The option that the user voted for.
- Properties:
- pollId: Stores the poll ID for which the vote was cast.
- userId: Stores the user ID of the voter.
- option: Stores the option that the user voted for.
- timestamp: Stores the date and time when the vote was cast.
2.PollManager Class
Purpose:Manages the entire polling system, including creating polls, managing votes, and viewing results.
Constructor:
- Properties:
- polls: A Map that stores all polls, where the key is the poll ID and the value is the Poll object.
- pollResults: A Map that stores the results of each poll, where the key is the poll ID and the value is another Map that tracks votes for each option.
- userVotes: A Map that stores the votes by each user, where the key is the poll ID and the value is another Map that tracks whether a user has voted in that poll.
Methods:
createPoll(question, options)
- Generates a new poll with a unique ID.
- Initializes the poll results, setting the vote count for each option to 0.
- Stores the poll and returns the generated poll ID.
updatePoll(pollId, question, options)
- Updates the question and options for an existing poll.
- Resets the poll results to 0 for the updated options.
- Returns a success message if the poll is found, otherwise returns "Poll not found."
deletePoll(pollId)
- Deletes a poll by its ID.
- Also removes associated poll results and user votes.
- Returns a success message if the poll is found, otherwise returns "Poll not found."
voteInPoll(pollId, userId, option)
- Allows a user to cast a vote in a specific poll.
- Ensures a user can only vote once per poll.
- Updates the vote count for the selected option if valid.
- Returns appropriate messages depending on whether the vote was successful, the user had already voted, or the poll or option was invalid.
viewPollResults(pollId)
- Returns the results of a specific poll in an array format, where each entry is a tuple of the option and its vote count.
- Returns "Poll not found" if the poll doesn't exist.
3.Example Usage
- Poll Creation:A poll is created asking, "What is your favorite color?" with options ["Red", "Blue", "Green", "Yellow"]. The poll ID is generated as "1".
- Voting:Multiple users vote in the poll, and the system ensures users can only vote once.
- Viewing Results:The poll results are displayed, showing the vote counts for each option.
- Updating the Poll:The poll's question and options are updated, resetting the results.
- Voting in Updated Poll:A user votes in the updated poll, and the results are displayed.
- Poll Deletion:The poll is deleted, and an attempt to view the results afterward confirms the poll no longer exists.
This implementation provides a basic but functional polling system, handling common scenarios such as poll creation, updating, voting, and deletion.
CODE
class Poll { constructor(id, question, options) { this.pollId = id; this.question = question; this.options = options; this.createdAt = new Date(); } } class Vote { constructor(pollId, userId, option) { this.pollId = pollId; this.userId = userId; this.option = option; this.timestamp = new Date(); } } class PollManager { constructor() { this.polls = new Map(); this.pollResults = new Map(); this.userVotes = new Map(); } createPoll(question, options) { const pollId = (this.polls.size + 1).toString(); const poll = new Poll(pollId, question, options); this.polls.set(pollId, poll); const result = new Map(); options.forEach(option => result.set(option, 0)); this.pollResults.set(pollId, result); return pollId; } updatePoll(pollId, question, options) { const poll = this.polls.get(pollId); if (poll) { poll.question = question; poll.options = options; // Update results for the new options const result = new Map(); options.forEach(option => result.set(option, 0)); this.pollResults.set(pollId, result); return "Poll updated successfully."; } return "Poll not found."; } deletePoll(pollId) { if (this.polls.delete(pollId)) { this.pollResults.delete(pollId); this.userVotes.delete(pollId); return "Poll deleted successfully."; } return "Poll not found."; } voteInPoll(pollId, userId, option) { const poll = this.polls.get(pollId); if (poll) { if (!this.userVotes.has(pollId)) { this.userVotes.set(pollId, new Map()); } const userVote = this.userVotes.get(pollId); if (userVote.get(userId)) { return "User has already voted."; } const result = this.pollResults.get(pollId); if (result.has(option)) { result.set(option, result.get(option) + 1); userVote.set(userId, true); return "Vote cast successfully."; } else { return "Invalid option."; } } return "Poll not found."; } viewPollResults(pollId) { const results = this.pollResults.get(pollId); if (results) { return Array.from(results.entries()); } return "Poll not found."; } } // Example usage const pollManager = new PollManager(); // Creating a poll const pollId = pollManager.createPoll("What is your favorite color?", ["Red", "Blue", "Green", "Yellow"]); console.log("Poll created with ID:", pollId); // Voting in the poll let voteMessage = pollManager.voteInPoll(pollId, "user1", "Red"); console.log(voteMessage); voteMessage = pollManager.voteInPoll(pollId, "user2", "Blue"); console.log(voteMessage); voteMessage = pollManager.voteInPoll(pollId, "user1", "Green"); console.log(voteMessage); // Should inform the user has already voted // Viewing poll results let results = pollManager.viewPollResults(pollId); console.log("Poll results for poll ID", pollId, ":", results); // Updating the poll let updateMessage = pollManager.updatePoll(pollId, "What is your favorite primary color?", ["Red", "Blue", "Yellow"]); console.log(updateMessage); // Voting in the updated poll voteMessage = pollManager.voteInPoll(pollId, "user3", "Yellow"); console.log(voteMessage); // Viewing updated poll results results = pollManager.viewPollResults(pollId); console.log("Updated poll results for poll ID", pollId, ":", results); // Deleting the poll let deleteMessage = pollManager.deletePoll(pollId); console.log(deleteMessage); // Attempting to view results of a deleted poll results = pollManager.viewPollResults(pollId); if (typeof results === "string") { console.log(results); } // Response // Poll created with ID: 1 // Vote cast successfully. // Vote cast successfully. // User has already voted. // Poll results for poll ID 1 : [['Red', 1], ['Blue', 1], ['Green', 0], ['Yellow', 0]] // Poll updated successfully. // Vote cast successfully. // Updated poll results for poll ID 1 : [['Red', 0], ['Blue', 0], ['Yellow', 1]] // Poll deleted successfully. // Poll not found.
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