SimpleDB

SimpleDB is a simple document database written in C++. It stores collections of documents on disk as JSON files and provides basic operations: insert, find, update and remove.

Overview

• Language: C++
• Build system: CMake
• Core classes: Document, Collection, and DocumentDB
• Persistence: each Collection is saved to a JSON file inside a base directory (e.g.: users/)

Features

• Insert documents (string key/value pairs)
• Find by field (e.g., find all documents with city = "Detroit")
• Retrieve all documents from a collection
• Find by ID
• Update document fields
• Remove document by ID
• Simple per-collection JSON persistence

Main code structure

• Document — represents a document (ID + map of string -> string). Provides string and JSON conversion.
• Collection — manages a list of Documents, handles reading/writing to disk (<basePath><collectionName>.json), tracks nextId and implements CRUD operations.
• DocumentDB — manages multiple collections and creates the base directory where collection files are stored.

Requirements

• C++ compiler(e.g., g++ >= 10, recent clang++)
• CMake >= 3.10 (the CMakeLists specifies 3.31.6, so using CMake >= 3.31 is recommended)

How to build

From the project root (command line):

mkdir -p build && cd build
cmake ..
cmake --build .

This will create the SimpleDB executable inside the build directory (or according to your CMake configuration).

How to run

From the build directory where the executable was generated:

Linux/Mac:

./SimpleDB

Windows:

SimpleDB.exe

The example main.cpp creates a DocumentDB with base path users/, gets the users collection, inserts some documents, lists all documents and performs a field search. Running will also create/update the file users/users.json with persisted data.

Example approximate output:

=== Data base in disc ===

=== Insert documents ===
Inserted documents with IDs: 1, 2, 3

=== All documents ===
{ _id: 1, name: "Kobra1", age: "30", city: "Detroit" }
{ _id: 2, name: "Kobra2", age: "25", city: "Santiago" }
{ _id: 3, name: "Kobra3", age: "40", city: "São Paulo" }

=== Search by city ===
{ _id: 1, name: "Kobra1", age: "30", city: "Detroit" }

=== Update document ID 1 ===
{ _id: 1, name: "Kobra1", age: "40", city: "Detroit" }

Quick usage API (example)

#include "DocumentDB.h"

int main() {
    DocumentDB db("users/");
    auto coll = db.getCollection("users");

    // Insert
    int id = coll->insert({{"name","Alice"}, {"city","Lisbon"}});

    // Find all
    auto all = coll->findAll();

    // Find by field
    auto res = coll->find("city", "Lisbon");

    // Update
    coll->update(id, "name", "Alice Silva");

    // Remove
    coll->remove(id);

    return 0;
}

Data location

By default DocumentDB creates the base directory passed to the constructor (e.g.: users/). Each collection is stored in <basePath><collectionName>.json (for example users/users.json).

License

Source files include headers indicating GPL (see source files). If desired, add a LICENSE file with the full text of the appropriate GPL license.

Contact

Credits: M3t4l

Contributions and issues are welcome.