PostGraphile Apple Example

This is an example of using PostGraphile with data generated from the Wikipedia page on the history of Apple products and very simple row level security policies.

Installing the database

Clone down this repository and change directory into it.

Assuming you have PostgreSQL running locally with "trust" authentication, first create the graphql role using password insecure:

createuser --pwprompt graphql

Next create the postgraphile_apple schema, and populate it with our example_schema.sql file:

createdb postgraphile_apple
psql -X1v ON_ERROR_STOP=1 -f example_schema.sql postgraphile_apple

Running

If you don't already have yarn, install it:

npm install -g yarn

Install the dependencies:

yarn

Then run PostGraphile:

yarn postgraphile

For future runs, only the yarn postgraphile command is necessary (but be sure to run it from inside the project directory, otherwise the configuration will not be pulled in).

Configuration

The configuration is in .postgraphilerc.js; we've pulled in a number of plugins that are particularly useful when building internal tooling for a company. In general we wouldn't necessarily recommend these plugins for production when you are exposing a PostGraphile schema to the internet (in these cases a much more tightly defined schema is recommended).

If you are not using a local database, or your database is not configured for "trust" authentication, or you are not a database superuser, you will need to change the connection and ownerConnection strings to suitable connection strings for you. If unsure, try with the default config, and dig in if there are errors.

Authentication

This is designed as a public API (i.e. anyone can request data from it), but where certain data is protected and requires authentication via JWT. You can go and run queries at http://localhost:5000 without entering any authentication details.

To enter a JWT in GraphiQL, look below the query pane where "Query Variables" and "Request Headers" can be seen. Select "Request Headers" and replace its contents with the following non-admin JWT header configuration:

{
  "Authorization": "Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJhdWQiOiJwb3N0Z3JhcGhpbGUiLCJlbWFpbCI6ImJlbmppZUBncmFwaGlsZS5jb20iLCJpc19hZG1pbiI6ZmFsc2V9.QJTdmPDqD-CMBMI5Nooy01wi_4cQbPjIAVXKinUs3io"
}

You can replace the JWT token with an admin token if you prefer:

{
  "Authorization": "Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJhdWQiOiJwb3N0Z3JhcGhpbGUiLCJlbWFpbCI6ImJlbmppZUBncmFwaGlsZS5jb20iLCJpc19hZG1pbiI6dHJ1ZX0.IQJYLT7AhxiCbLkzJyKj05FL2dCNnqwkK-xHY3bMtD8"
}

You can see the content of these tokens at JWT.io; critically the aud must be postgraphile, and (according to our configuration) the JWT secret is the word secret. These are NOT secure tokens, in a production app be sure to use a cryptographically secure secret!

NOTE: JWT is not required to use PostGraphile but it's very easy to demo. PostGraphile can run as a middleware in many Node.js server frameworks, so any authentication method supported by those frameworks (Express, Koa, Fastify, etc.) should work with PostGraphile.

Example queries

You can paste the following code block into GraphiQL at http://localhost:5000/ and then select the query to run from the "Play button" dropdown, or alternatively click inside the relevant query and perform ⌘↵ (Command-Enter) on your keyboard.

# Paginate through product history
query Products($after: Cursor) {
  products(first: 5, after: $after, orderBy: [RELEASED_ASC]) {
    nodes {
      id
      family
      model
      released
    }
    pageInfo {
      hasNextPage
      endCursor
    }
  }
}

# View the products various emails are permitted to access
# (NOTE: this will change based on your JWT token!)
query AppleExample {
  authorisedEmails {
    nodes {
      email
      product {
        id
        family
        model
        released
      }
    }
  }
}

query Aggregates {
  aggregates: products(filter: { released: { isNull: false } }) {
    # Find the number of products (the count of distinct product ids) released
    # each year.

    productsPerYear: groupedAggregates(groupBy: [RELEASED_TRUNCATED_TO_YEAR]) {
      keys
      distinctCount {
        id
      }
    }

    # Find families with more than 20 products in, and their count of products
    families: groupedAggregates(
      groupBy: [FAMILY]
      having: { distinctCount: { id: { greaterThan: 20 } } }
    ) {
      keys
      distinctCount {
        id
      }
    }
  }
}

The schema

The schema is defined in example_schema.sql and has some documentation inline. The descriptions for some of the functions/tables/fields can be found at the bottom of the file in COMMENT statements. Feel free to edit and re-run the file using the psql command line above and then restart PostGraphile to see the changes. (If watch mode is working, you might not even have to restart!)

How the data was generated

This part is just for interest. Visit the Wikipedia page for the Timeline of Apple Inc. products and then open your browser devtools. Paste in the code from apple_products_from_wikipedia.js and you should find that the SQL values are now in your clipboard. This is liable to break any time Wikipedia changes it's formatting (or any time data is added to that page that does not conform to the assumptions of the script.)

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