Simple GraphQL API with PostgreSQL

This is a simple project for beginners to get their hands dirty and develop a GraphQL API with the help Apollo Server, using the apollo-server-express library. Also, with this project you can explore how to implement a simple connection between a PostgreSQL database and a GraphQL server, with the pg-promise library.

• Node.js
• Express.js
• Apollo server (apollo-server-express)
• PostgreSQL (pg-promise)
• nodemon (v2.0.3)

Note: This project does not use any particular style guides, and you are free to make a pull request and improve the code as you like.

Getting started

Prerequisites

• Node.js (v14.0.0)
• express (v4.17.1)
• PostgreSQL (v12)
• pg-promise (v10.5.2)

You can follow the links of the above list, to see explicit instructions on how to install the correnponding package into your operating system. However, you only need Node.js & PostgreSQL before proceeding.

Installation & Local development

After cloning the GitHub repository to your system, please follow below the instructions:

1. Make sure you cd into the correct folder, where all of the app files are located, before proceeding with the following steps. Also, you will need the latest version of Node.js & PostgreSQL, as noticed above.

2. Install the dependencies:

$  npm install

3. Run the db.psql file, to create the tables, domains and enums in your PostgreSQL server.

$  sudo -u postgres
$  cd ../<back again to code directory>
$  psql -f db.psql

4. (optional): You can also seed the tables with some sample data, using the sample_data.psql file:

$  psql -f sample_data.psql

5. Go ahead and config accordingl the .env, which is going to be responsible for storing valuable and sensitive data for accessing the database. Please complete the file like this:

DB_USERNAME=<your_database_username>
DB_PASSWORD=<your_database_password>
DB_NAME=<your_database_name>
DB_HOST="127.0.0.1" // or "localhost"
DB_PORT=5432

6. Run the GraphQL API server, by one of the following ways:

$  nodemon server.js

or

$  npm start

or

$  npm run start

7. Now you have the API setted up and running.

API Documentation

Getting Started

• Base URL: At present this app can only be run locally and is not hosted as a base URL somewhere live on the web. The GraphQL API is currently hosted at the default port of your computer, http://127.0.0.1:5000/, or http://localhost:5000/, which is set as a proxy in the package.json configuration file.
• Authentication: This version of the application does not require and does not use authentication or API keys, to have access on its data.

Queries

Retrive all available hotels

---

query {
  hotels {
    id
    name
    category
    price
    avg_rating
    updated_at
    timestamp
  }
}

Response:

{
  "data": {
    "hotels": [
      {
        "id": 1,
        "name": "Cassandra Hotel",
        "category": "Hotel",
        "price": 12,
        "avg_rating": 3.2,
        "updated_at": "2020-04-28T10:30:22.267Z",
        "timestamp": "2020-04-28T10:30:17.603Z"
      }
    ]
  }
}

& the owner information

query {
    hotels {
        ...
        owner {
            id
            first_name
            last_name
        }
    }
}

Response:

{
  "data": {
    "hotels": [
      {
        "owner": [
          {
            "id": 1,
            "first_name": "George",
            "last_name": "Krachtopoulos"
          }
        ]
      }
    ]
  }
}

& their location details

query {
    hotels {
        ...
        location {
            id
            address
            city
            area
        }
    }
}

Response:

{
  "data": {
    "hotels": [
      {
        "location": [
          {
            "id": 1,
            "address": "Kryopigi 25",
            "city": "Chalkidiki",
            "area": null
          }
        ]
      }
    ]
  }
}

& all their reviews and ratings

query {
    hotels {
        ...
        reviews {
            id
            rating
            body
        }
    }
}

Response:

{
  "data": {
    "hotels": [
      {
        "reviews": [
          {
            "id": 1,
            "rating": 4,
            "body": null
          },
          {
            "id": 2,
            "rating": 5,
            "body": null
          }
        ]
      }
    ]
  }
}

Retrieve a single hotel

---

Reuqest arguments:

• id: Int!

query {
  hotel(id: 1) {
    id
    name
    category
    price
    avg_rating
    updated_at
    timestamp
  }
}

Response:

{
  "data": {
    "hotel": [
      {
        "id": 1,
        "name": "Cassandra Hotel",
        "category": "Hotel",
        "price": 12,
        "avg_rating": 3.2,
        "updated_at": "2020-04-28T10:30:22.267Z",
        "timestamp": "2020-04-28T10:30:17.603Z"
      }
    ]
  }
}

Retrive all hotel reviews

---

query {
  reviews {
    id
    rating
    body
  }
}

Response:

{
  "data": {
    "reviews": [
      {
        "id": 1,
        "rating": 4,
        "body": null
      },
      {
        "id": 2,
        "rating": 5,
        "body": null
      }
    ]
  }
}

& with the hotel information for a specific review

query {
  reviews {
    id
    rating
    body
    hotel {
      id
      name
      category
      price
      avg_rating
      updated_at
      timestamp
    }
  }
}

Response:

{
  "data": {
    "reviews": [
      {
        "id": 1,
        "rating": 4,
        "body": null,
        "hotel": [
          {
            "id": 1,
            "name": "Cassandra Hotel",
            "category": "Hotel",
            "price": 12,
            "avg_rating": 3.2,
            "updated_at": "2020-04-28T10:30:22.267Z",
            "timestamp": "2020-04-28T10:30:17.603Z"
          }
        ]
      },
      {
        "id": 2,
        "rating": 5,
        "body": null,
        "hotel": [
          {
            "id": 1,
            "name": "Cassandra Hotel",
            "category": "Hotel",
            "price": 12,
            "avg_rating": 3.2,
            "updated_at": "2020-04-28T10:30:22.267Z",
            "timestamp": "2020-04-28T10:30:17.603Z"
          }
        ]
      }
    ]
  }
}

Retrieve all hotel locations

---

query {
  locations {
    id
    address
    city
    area
  }
}

Response:

{
  "data": {
    "locations": [
      {
        "id": 1,
        "address": "Kryopigi 25",
        "city": "Chalkidiki",
        "area": null
      }
    ]
  }
}

Retrieve all hotel owners

---

query {
  owners {
    id
    first_name
    last_name
  }
}

Response:

{
  "data": {
    "owners": [
      {
        "id": 1,
        "first_name": "George",
        "last_name": "Krachtopoulos"
      }
    ]
  }
}

Authors

This project is initally created by me, George Krachtopoulos. Please feel free to contact me if you need any help, and make sure to follow me for more updates.