Problem Controller

Overview

The problem_controller handles all operations related to problems including CRUD operations, test case management, import/export functionality, and problem metadata editing.

Constructor

public function __construct()

Applies the following middleware:

auth - Requires user authentication
read_only_archive - Makes controller read-only when app is in archived mode
ip_white_listing - IP whitelist validation

CRUD Methods

index()

public function index(Request $request)

Displays a paginated listing of problems with filtering and search capabilities.

string

Search term to filter problems by name

tag_id

array

Array of tag IDs to filter problems

owners

array

Array of usernames to filter by problem owner

Access Control:

Admin: Can view all problems
Others: Can only view problems available to them

Returns: Paginated view with:

Problem list with assignments and languages
Total submissions count per problem
Accepted submissions count per problem
Acceptance ratio
All tags for filtering
All problem owners for filtering

Example from controller:

if (Auth::user()->role->name == "admin") {
    $all_problem = Problem::latest();
} else {
    $all_problem = Problem::available(Auth::user()->id)->latest();
}

// Apply filters
if ($request->get("search") != "") {
    $all_problem->where("name", "like", "%" . trim($request->get("search")) . "%");
}
if ($request->get("tag_id") != null) {
    $all_problem->whereHas("tags", function (Builder $query) use ($request) {
        $query->whereIn("tag_id", $request->get("tag_id"));
    });
}

create()

public function create()

Shows the form for creating a new problem. Access Control:

Admin, head_instructor, and instructor only
Aborts with 404 for other roles

Returns: View with:

All available languages (ordered by sorting)
Maximum file uploads limit
All available tags
Empty problem instance

store()

public function store(Request $request)

Stores a newly created problem in the database.

name

string

required

Problem name (max 255 characters)

admin_note

text

Administrative notes about the problem

allow_practice

boolean

Allow problem to appear in practice mode

sharable

boolean

Allow other instructors to use this problem

allow_input_download

boolean

Allow students to download input test cases

allow_output_download

boolean

Allow students to download output test cases

tag_id

array

Array of tag IDs or new tag names (prefixed with #)

enable

array

required

Array of 1/0 indicating which languages are enabled

language_id

array

required

Array of language IDs corresponding to enable array

time_limit

array

required

Array of time limits (seconds) for each language

memory_limit

array

required

Array of memory limits (KB) for each language

tests_zip

file

ZIP file containing test cases (in/ and out/ folders)

tests_dir

array

Array of individual test files to upload

rename_zip

boolean

Whether to rename test files sequentially when extracting ZIP

Validation Rules:

name: required, max 255 characters

Returns: Redirect to problems index with messages Example from controller:

$langs = [];
foreach ($request->input("enable") as $i => $lang) {
    if ($lang == 1) {
        $langs += [
            $request->input("language_id")[$i] => [
                "time_limit" => $request->input("time_limit")[$i],
                "memory_limit" => $request->input("memory_limit")[$i],
            ],
        ];
    }
}

$problem["user_id"] = Auth::user()->id;
$p = Problem::create($problem);
$p->languages()->sync($langs);

show()

public function show($id)

Attempts to display a problem directly (not through assignment). Note: This method always aborts with 404 because problems can only be viewed through assignments or practice mode.

edit()

public function edit(Problem $problem)

Shows the form for editing an existing problem.

problem

Problem

required

Problem model instance to edit

Access Control:

Calls _can_edit_or_404() to verify permissions

Returns: View with:

Problem data
Problem’s languages with pivot data
Problem’s tags
All available languages and tags
Directory tree dump of test cases

Example from controller:

$lang_of_problems = $problem->languages->keyBy("id");
$tags = $problem->tags->keyBy("id");
return view("problems.create", [
    "problem" => $problem,
    "languages" => $lang_of_problems,
    "tags" => $tags,
    "tree_dump" => shell_exec("tree -h " . $problem->get_directory_path()),
]);

update()

public function update(Request $request, Problem $problem)

Updates the specified problem in storage.

problem

Problem

required

Problem model instance to update

name

string

required

Problem name (max 255 characters)

editorial

url

URL to problem editorial

Validation Rules:

name: required, max 255 characters
editorial: nullable, must be valid URL

Process:

Updates problem metadata
Syncs tags (creates new tags if needed)
Replaces language configurations
Processes test file uploads if provided

Returns: Redirect to problems index with messages

destroy()

public function destroy($id = null)

Removes the specified problem from storage.

integer

required

Problem ID to delete

Access Control:

Admin, head_instructor, and instructor only
Calls _can_edit_or_404() to verify ownership

Deletion Rules:

Cannot delete if problem appears in assignments
Cannot delete if problem has submissions

Returns: JSON response:

{
  "done": 1,
  "message": "Optional error message"
}

Test Case Methods

downloadtestsdesc()

public function downloadtestsdesc($id)

Downloads the problem description file (desc.html).

integer

required

Problem ID

Note: Route is defined but implementation not shown in provided code. Route: /problems/downloadtestsdesc/{id}

download_testcases()

public function download_testcases(Problem $problem, Assignment $assignment, $type = null)

Downloads input or output test cases for a problem.

problem

Problem

required

Problem model instance

assignment

Assignment

required

Assignment model instance (for permission check)

type

string

required

Type of files to download: “in” or “out”

Access Control:

User must be able to submit to the assignment
Input download requires allow_input_download flag
Output download requires allow_output_download flag

Returns: ZIP file download with automatic deletion Route: /problems/downloadtestcases/{problem}/{assignment}/{type} Example from controller:

$check = $assignment->can_submit(Auth::user(), $problem);
if (!$check->can_submit) {
    abort(403, $check->error_message);
}

if ($type == "in" && $problem->allow_input_download == false) {
    abort(403, "This problem does not allow input download");
}

$pathdir = $assignments_root . "/problems/" . $problem->id . "/" . $type . "/";
shell_exec("cd $pathdir && zip -r $zipFile *");
return response()->download($zipFile)->deleteFileAfterSend();

Import/Export Methods

export()

public function export(Request $request)

Exports one or more problems as a ZIP file with metadata.

ids

string

required

Comma-separated list of problem IDs to export

Access Control:

Admin: Can export any problem
Others: Can only export sharable problems or their own problems

Export Includes:

Test cases (in/ and out/ folders)
Problem description (desc.html)
Metadata JSON file (problem.wecode.metadata.json)
PDF files if present
Templates if present

Returns: ZIP file download with automatic deletion Route: /problems/export (GET) Example from controller:

$ids = explode(",", $request->input("ids"));
$probs = Problem::whereIn("id", $ids)->get()->load("user");

if (!in_array(Auth::user()->role->name, ["admin"])) {
    $probs = $probs->reject(fn(Problem $prob, int $key)
        => !($prob->sharable && Auth::user()->role->name != "student") 
           && $prob->user->id != Auth::user()->id
    );
}
$probs->load("languages")->load("tags");

foreach ($probs as $prob) {
    $pathdir = $prob->get_directory_path();
    $metadata_file = $pathdir . "/problem.wecode.metadata.json";
    file_put_contents($metadata_file, $prob->toJSON(JSON_PRETTY_PRINT));
    shell_exec("cd $pathdir/.. && zip -r $zipFile " . $prob->id . "/*");
    unlink($metadata_file);
}

import()

public function import(Request $request)

Imports problems from a ZIP file exported by the export function.

zip_upload

file

required

ZIP file containing exported problems

Access Control:

Admin and head_instructor only

Validation Rules:

zip_upload: required

Import Process:

Extracts ZIP to temporary directory
Reads metadata JSON from each problem folder
Creates new problem with metadata
Maps language names to IDs
Creates new tags if they don’t exist
Copies test case files to problem directory
Updates admin_note with import information

Returns: Redirect to problems index with error messages if any Route: /problems/import (POST) Example from controller:

$lang_to_id = Language::all()->pluck("id", "name");
$tag_to_id = Tag::all()->pluck('id', 'text');

foreach ($storage->directories($tmp_dir) as $prob_folder) {
    $metadata = json_decode(
        $storage->get("$prob_folder/problem.wecode.metadata.json")
    );
    
    $problem = new Problem((array) $metadata);
    $problem->id = null;
    $problem->user_id = Auth::user()->id;
    $problem->admin_note .= sprintf(
        "\nIMPORTED: original user %s(%s), updated %s",
        $metadata->user->username,
        $metadata->user->email,
        new Carbon\Carbon($metadata->updated_at)
    );
    $problem->save();
    
    // Map languages and sync
    $langs = [];
    foreach ($metadata->languages as $lang) {
        if (!isset($lang_to_id[$lang->name])) continue;
        $langs[$lang_to_id[$lang->name]] = [
            "time_limit" => $lang->pivot->time_limit,
            "memory_limit" => $lang->pivot->memory_limit,
        ];
    }
    $problem->languages()->sync($langs);
}

Description Methods

edit_description()

public function edit_description(Request $request, Problem $problem)

Updates the problem description (desc.html file).

problem

Problem

required

Problem model instance

content

text

required

HTML content for problem description

Access Control:

Admin, head_instructor, and instructor only

Returns: Plain text response:

"success" - Description saved successfully
"error" - Failed to save description

Route: /problems/edit_description/{problem} (POST) Example from controller:

private function save_problem_description(Problem $problem, $text, $type = "html") {
    $problem_dir = $problem->get_directory_path();
    if (file_put_contents("$problem_dir/desc.html", $text)) {
        return true;
    } else {
        return false;
    }
}

Toggle Methods

toggle_practice()

public function toggle_practice(Request $request, string $query)

Toggles the practice mode or sharable status of a problem.

query

string

required

Format: “practice.” or “sharable.”

Access Control:

Calls _can_edit_or_404() to verify permissions

Returns: Boolean value (true/false) of new state Route: /problems/toggle_practice/{query?} (POST) Example from controller:

$a = explode(".", $query);
$task = $a[0];
$id = $a[1];

$problem = Problem::find($id);
if ($task == "practice") {
    $problem->allow_practice = !$problem->allow_practice;
    $problem->save();
    return $problem->allow_practice;
} else {
    $problem->sharable = !$problem->sharable;
    $problem->save();
    return $problem->sharable;
}

edit_tags()

public function edit_tags(Request $request, Problem $problem)

Updates the tags associated with a problem.

problem

Problem

required

Problem model instance

tag_id

array

required

Array of tag IDs or new tag names (prefixed with #)

Access Control:

Calls _can_edit_or_404() to verify permissions

Process:

Creates new tags if they don’t exist (tags prefixed with #)
Syncs problem’s tags with provided list

Returns: JSON response:

{
  "all_tags": [...],
  "new_tags": [...]
}

Route: /problems/edit_tags/{problem?} (POST) Example from controller:

private function _add_missing_tags($tags) {
    foreach ($tags as $i => $tag) {
        if (Tag::find($tag) == null) {
            $tag = substr($tag, 1); // Remove '#' from new tag
            if (Tag::where("text", $tag)->first() == []) {
                $new_tag = new Tag();
                $new_tag->text = $tag;
                $new_tag->save();
                $tags[$i] = (string) $new_tag->id;
            }
        }
    }
    return $tags;
}

Test File Upload

Test cases can be uploaded in two formats:

ZIP File Format

Structure:

problem.zip
├── desc.html (optional)
├── desc.pdf (optional)
├── in/
│   ├── input1.txt
│   ├── input2.txt
│   └── ...
└── out/
    ├── output1.txt
    ├── output2.txt
    └── ...

Notes:

Input files must be named input{N}.txt where N starts from 1
Output files must be named output{N}.txt matching input numbers
Can enable rename_zip to automatically rename files sequentially

Directory Upload Format

Upload individual files:

desc.html - Problem description (required)
input1.txt, input2.txt, … - Input test cases
output1.txt, output2.txt, … - Output test cases

Problem: Main model for problems
Language: Programming languages supported
Tag: Tags for categorizing problems
Assignment: Assignments that include problems
Submission: Student submissions for problems
User: Problem creator/owner

Models

Controllers

Routes

Problem Controller

Overview

Constructor

CRUD Methods

index()

create()

store()

show()

edit()

update()

destroy()

Test Case Methods

downloadtestsdesc()

download_testcases()

Import/Export Methods

export()

import()

Description Methods

edit_description()

Toggle Methods

toggle_practice()

edit_tags()

Test File Upload

ZIP File Format

Directory Upload Format

Build docs developers (and LLMs) love

Models

Controllers

Routes

​Overview

​Constructor

​CRUD Methods

​index()

​create()

​store()

​show()

​edit()

​update()

​destroy()

​Test Case Methods

​downloadtestsdesc()

​download_testcases()

​Import/Export Methods

​export()

​import()

​Description Methods

​edit_description()

​Toggle Methods

​toggle_practice()

​edit_tags()

​Test File Upload

​ZIP File Format

​Directory Upload Format

​Related Models

Build docs developers (and LLMs) love

Overview

Constructor

CRUD Methods

index()

create()

store()

show()

edit()

update()

destroy()

Test Case Methods

downloadtestsdesc()

download_testcases()

Import/Export Methods

export()

import()

Description Methods

edit_description()

Toggle Methods

toggle_practice()

edit_tags()

Test File Upload

ZIP File Format

Directory Upload Format

Related Models