String Analysis API

A RESTful API built with Express.js to create, analyze, filter, retrieve, and delete strings. This API provides detailed properties for strings, including length, palindrome status, unique characters, word count, and SHA-256 hash. It also supports filtering strings using query parameters or natural language queries.

Table of Contents

• Installation
• Usage
• Endpoints
• Examples
• Data Structure
• Setup Example with cURL

Installation

1. Clone the repository:

git clone <repository_url>
cd <repository_folder>

2. Install dependencies:

npm install

3. Start the server:

npm start

By default, the server runs on http://localhost:3000.

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Usage

Send HTTP requests to the API using tools like Postman, cURL, or any HTTP client. The API supports JSON payloads for creating strings and query parameters for filtering.

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Endpoints

1. Create and Analyze String

POST /strings

Request Body:

{
	"value": "string to analyze"
}

Responses:

• 201 Created – Returns the created string with analysis properties.
• 400 Bad Request – Missing or invalid value.
• 409 Conflict – String already exists.
• 422 Unprocessable Entity – value is not a string.

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2. Get All Strings with Filtering

GET /strings

Query Parameters (optional):

• is_palindrome (true/false)
• min_length (number)
• max_length (number)
• word_count (number)
• contains_character (string)

Response:

• 200 OK – Returns an array of strings matching filters.
• 400 Bad Request – Invalid query parameter values.

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3. Natural Language Filtering

GET /strings/filter-by-natural-language?query=<query_string>

Response:

• 200 OK – Returns filtered strings based on natural language query.
• 400 Bad Request – Unable to parse query.
• 422 Unprocessable Entity – Conflicting filters in query.

Example Queries:

• "palindromic string longer than 5 words"
• "string containing the first vowel shorter than 10 characters"

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4. Get Specific String

GET /strings/:value

Response:

• 200 OK – Returns the string object.
• 404 Not Found – String does not exist.

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5. Delete String

DELETE /strings/:string_value

Response:

• 204 No Content – Successfully deleted.
• 404 Not Found – String does not exist.

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Data Structure

Each string object has the following structure:

{
	"id": "sha256_hash",
	"value": "string value",
	"properties": {
		"length": 17,
		"is_palindrome": false,
		"unique_characters": 12,
		"word_count": 3,
		"sha256_hash": "sha256_hash",
		"character_frequency_map": {
			"s": 1,
			"t": 2
		}
	},
	"created_at": "ISO8601 timestamp"
}

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Setup Example with cURL

Create a string

curl -X POST http://localhost:3000/strings \
-H "Content-Type: application/json" \
-d '{"value":"never odd or even"}'

Get all strings

curl http://localhost:3000/strings

Filter strings by query parameters

curl "http://localhost:3000/strings?is_palindrome=true&min_length=5"

Filter strings using natural language query

curl "http://localhost:3000/strings/filter-by-natural-language?query=palindromic string longer than 5 characters"

Get a specific string

curl http://localhost:3000/strings/never%20odd%20or%20even

Delete a string

curl -X DELETE http://localhost:3000/strings/never%20odd%20or%20even