This project provides a C++ web service that interacts with a PostgreSQL database. The service allows users to create tables, insert data, update records, read all records, and delete records through HTTP requests using the Crow web framework.

Before running the project, ensure you have the following dependencies installed:

• C++ Compiler: Install a C++ compiler like g++ or clang++. For example, on Ubuntu, you can install g++ using:

  sudo apt-get update
  sudo apt-get install g++

• PostgreSQL and libpqxx: Install PostgreSQL and the libpqxx library for C++ to interact with PostgreSQL. On Ubuntu, you can use:

sudo apt-get update
sudo apt-get install postgresql libpqxx-dev libasio-dev
sudo apt-get inatsll libxlsxwriter-dev
sudo apt-get install libhpdf-dev

• Crow Web Framework: header is provided in the repo
• Install OpenSSL:

  sudo apt-get install libssl-dev

• Install nlohmann-json: This JSON library is a dependency for jwt-cpp.

sudo apt-get install nlohmann-json3-dev

• Clone the jwt-cpp repository:

git clone https://github.com/Thalhammer/jwt-cpp.git

• Navigate to the jwt-cpp directory:

cd jwt-cpp

• Build the project using CMake or copy the headers directly to your project.
• Update the linker cache:

sudo ldconfig

To create a user and a database in PostgreSQL, follow these steps:

1. Access the PostgreSQL command line as the postgres user:

   sudo su - postgres
   psql
   

2. Create a new user:

   CREATE USER username WITH PASSWORD 'password';
   

   Replace username with the desired username and 'password' with the desired password.

3. Create a new database:

   CREATE DATABASE database_name OWNER username;
   

   Replace database_name with the desired database name and username with the username of the user who will own the database.

4. Exit from the postgres user shell:

   \q
   exit
   

• split(const std::string& s, char delimiter): Splits a string by a specified delimiter and returns a vector of tokens.

• extract_number(const std::string& column_name): Extracts and returns the number found in a column name.

• get_id_from_columns(const std::string& json_data): Extracts the ID from the column names in a JSON string.

• parseTableSchema(const std::string& schema, std::string& tableName, std::vector<std::string>& columns): Parses the table schema from a JSON-like string to extract the table name and columns.

• join(const std::vector<std::string>& elements, const std::string& delimiter): Joins a vector of strings into a single string with a specified delimiter.

• create_table(pqxx::work& work, const std::string& table_name, Columns&&... columns): Creates a table in the database with specified columns.

• parse_column_value(const std::string& column_value): Parses a "column value" string into a tuple containing the column and value.

• insert(pqxx::work& W, const std::string& table, Args... args): Inserts values into a specified table.

• update(pqxx::work& W, const std::string& table, std::string id, T&&... ts): Updates a record in a specified table based on its ID.

• delete_record(pqxx::work& W, const std::string& table, std::string id): Deletes a record from a specified table based on its ID.

• read_all_rows(pqxx::work& W, const std::string& table): Reads and prints all rows from a specified table.

Creates a new table with the specified schema.

Request Body Format:

{
  "table_name": "string",
  "columns": ["column_name DATA_TYPE", ...]
}

Example:

{
  "table_name": "users",
  "columns": ["name TEXT", "email TEXT", "age INTEGER"]
}

Inserts a new record into the specified table.

Request Body Format:

{
  "table_name": "string",
  "columns": {
    "column_name": "value",
    ...
  }
}

Example:

{
  "table_name": "users",
  "columns": {
    "name": "John Doe",
    "email": "[email protected]",
    "age": "30"
  }
}

Reads all rows from the specified table.

Query Parameter:

• table: The name of the table to read from.

Example:

GET /read_all?table=students

Updates a record in the specified table. The record is identified by the id column.

Request Body Format:

{
  "table_name": "string",
  "columns": {
    "id": "string",
    "column_name": "new_value",
    ...
  }
}

Example:

{
  "table_name": "users",
  "columns": {
    "id": "1",
    "name": "Jane Doe",
    "email": "[email protected]",
    "age": "31"
  }
}

Deletes a record from the specified table.

Request Body Format:

{
  "table_name": "users",
  "id": "1"
}

1. Compile the C++ code with g++:

 g++ main.cpp -o output -lpqxx -lpq -lssl -lcrypto

You may need to specify the path to headers

g++ main.cpp -o output -I/path/to/headers -lpqxx -lpq -lssl -lcrypto

2. Run the compiled executable:

  ./output

curl -X POST http://localhost:18080/ -H "Content-Type: application/json" -d '{"username": "test","password": "testpass" }'

curl -X GET "http://localhost:18080/read_all?table=test" -H "Authorization: Bearer -token generated-"