PostGraphile DB Session Init

This plugin enables you to run arbitrary SQL prior to each PostGraphile query execution.

The SQL that you provide will run after pgSettings. Hence, any session variables that you establish in pgSettings will be accessible in your SQL.

Installation

npm install postgraphile-db-session-init

Usage

The plugin requires a single argument: an object containing the following properties.

const { default: DbSessionInitPlugin } = require("postgraphile-db-session-init")

const dbSessionInitPlugin = DbSessionInitPlugin({
  sql: "INSERT INTO my_table (my_col) VALUES ('test')",
})

const pluginHook = makePluginHook([dbSessionInitPlugin, /* other plugins */])

const app = express()

app.use(
  postgraphile(db, schemas, {
    // ... other settings
    pluginHook,
  })
)

In this example, the DbSessionInitPlugin is used to create an instance of the plugin, initialized with a simple SQL command. The resulting instance is then included within the pluginHook which is passed into the postgraphile middleware during its initialization in the Express application.

Precondition

Defining a precondition function allows you to control when the provided SQL should be executed based on specific conditions.

The precondition function should return a boolean value. If the function returns true (or is undefined), the SQL command will be executed. On the other hand, if the function is returns false, the SQL command will not be executed.

const dbSessionInitPlugin = DbSessionInitPlugin({
  sql: 'INSERT INTO my_audit_log (user_id, action) VALUES ($1, $2)',
  precondition: (options) =>
    options.pgSettings &&
    'role' in options.pgSettings &&
    options.pgSettings.role === 'authenticated_user',
});

In this example, the SQL command will only be executed if the precondition conditions are met, specifically if the role in pgSettings is set to 'authenticated_user'.