Lightweight wrapper for csvlint.rb to provide web API

Gemfile

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+source 'https://rubygems.org'
+
+gem 'sinatra'
+gem 'csvlint'
+gem 'webrick'

Procfile

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+web: ruby csvlint_server.rb -p $PORT

README.md

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+# CSVLint-API
+
+CSVLint is a Ruby-based server for validating CSV files. It checks CSV files against standard structures and schemas, providing detailed feedback on any issues detected.
+
+## Features
+
+- **Structure Validation**: Checks for structural issues, such as inconsistent row lengths, incorrect quoting, and malformed line endings.
+- **Schema Validation**: Validates CSV data against schemas (e.g., JSON-based) to ensure data formats, types, and constraints are met.
+- **Dialect Options**: Flexible options for parsing CSV files, such as delimiters, quoting characters, and line terminators.
+- **Detailed Reporting**: Provides error, warning, and informational feedback on validation results.
+
+## Installation
+
+### Prerequisites
+
+Make sure you have the following installed on your system:
+
+- **Ruby** (version 2.6 or higher)
+- **Bundler** (for managing Ruby dependencies)
+
+### Step 1: Clone the Repository
+
+Clone the repository from GitHub and navigate into the project directory:
+
+```bash
+git clone https://github.com/theodi/csvlint-api.git
+cd csvlint-api
+```
+
+### Step 2: Install Ruby Dependencies
+
+Ensure you have Bundler installed. If not, you can install it with:
+
+```bash
+gem install bundler
+```
+
+Then install all required Ruby gems:
+
+```bash
+bundle install
+```
+
+### Step 3: Set Up Environment Variables
+
+Create an `.env` file in the project root (you can start by copying `.env.example`):
+
+```bash
+cp .env.example .env
+```
+
+Set any necessary environment variables in `.env`. At minimum, you should define:
+
+- `PORT`: The port on which the server will run (default: `4567`).
+
+### Step 4: Run the Server Locally
+
+To start the CSVLint server locally, use:
+
+```bash
+ruby csvlint_server.rb
+```
+
+The server will start on the specified port (default `4567`). You can access it at `http://localhost:4567`.
+
+### Usage
+
+#### Web Interface
+
+To use CSVLint through a web interface, simply open the URL in your browser:
+
+```bash
+http://localhost:4567
+```
+
+#### API Usage
+
+The CSVLint API allows you to programmatically validate CSV files. You can upload a CSV file or provide a URL to a CSV with optional schema and dialect options.
+
+**Example `POST` Request:**
+
+```bash
+curl -X POST http://localhost:4567/validate \
+-F "file=@/path/to/yourfile.csv" \
+-F "schema=@/path/to/yourschema.json" \
+-F "dialect={\"delimiter\":\",\",\"quoteChar\":\"\\\"\"}"
+```
+
+**Response:**
+
+The API responds with JSON validation results. Here’s an example response format:
+
+```json
+{
+  "valid": true,
+  "errors": [],
+  "warnings": [],
+  "info_messages": []
+}
+```
+
+#### Deploying to Render
+
+1. **Log in to Render** and create a new service.
+2. **Link your GitHub repository**.
+3. **Choose the Ruby environment** and specify `Gemfile` for dependencies.
+4. Set environment variables, including `PORT`.
+5. Click **Create Web Service** to deploy.
+
+### License
+
+This project is licensed under the MIT License.

config.ru

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+require './csvlint_server'
+run Sinatra::Application

csvlint_server.rb

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+require 'sinatra'
+require 'csvlint'
+require 'webrick'
+require 'securerandom'
+require 'json'
+
+set :port, ENV['PORT'] || 4567
+set :server, 'webrick'
+
+post '/validate' do
+  content_type :json
+
+  # Retrieve file, schema, and dialect from the request
+  csv_file = params[:file]
+  schema_file = params[:schema]
+  dialect = JSON.parse(params[:dialect] || '{}')  # Parse dialect JSON if provided
+
+  # Generate a unique temporary file name
+  csv_tempfile = "temp_#{SecureRandom.uuid}.csv"
+  schema_tempfile = "temp_schema_#{SecureRandom.uuid}.json" if schema_file
+
+  begin
+    # Save the CSV file temporarily
+    File.open(csv_tempfile, "wb") { |f| f.write(csv_file[:tempfile].read) }
+
+    # Save schema file if provided
+    schema = nil
+    if schema_file
+      File.open(schema_tempfile, "wb") { |f| f.write(schema_file[:tempfile].read) }
+      schema = Csvlint::Schema.load_from_json(File.new(schema_tempfile))
+    end
+
+    # Create the CSV validator with dialect options and schema
+    validator = Csvlint::Validator.new(File.new(csv_tempfile), dialect, schema)
+
+    # Perform validation
+    validator.validate
+
+    # Map errors, warnings, and info messages into hashes
+    errors = validator.errors.map do |error|
+      {
+        category: error.category,
+        type: error.type,
+        row: error.row,
+        column: error.column,
+        content: error.content
+      }
+    end
+
+    warnings = validator.warnings.map do |warning|
+      {
+        category: warning.category,
+        type: warning.type,
+        row: warning.row,
+        column: warning.column,
+        content: warning.content
+      }
+    end
+
+    info_messages = validator.info_messages.map do |info|
+      {
+        category: info.category,
+        type: info.type,
+        row: info.row,
+        column: info.column,
+        content: info.content
+      }
+    end
+
+    # Collect results
+    result = {
+      valid: validator.valid?,
+      errors: errors,
+      warnings: warnings,
+      info_messages: info_messages
+    }
+
+  rescue StandardError => e
+    # Handle errors gracefully and return the error message as JSON
+    result = { error: "Validation failed: #{e.message}" }
+  ensure
+    # Ensure temporary files are deleted
+    File.delete(csv_tempfile) if File.exist?(csv_tempfile)
+    File.delete(schema_tempfile) if schema_file && File.exist?(schema_tempfile)
+  end
+
+  # Return the result as JSON
+  result.to_json
+end