Adding Custom App Modifications

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From time to time, it may be useful for you (the developer) to add custom functionality to Flitter during initialization. This may be custom Express add-ons, tweaking settings of the underlying Express app, or any number of other things. As such, Flitter comes with a MiscUnit for these customizations. This unit in the file app/MiscUnit.js and follows the exact same structure as every other unit. It is loaded after the core Flitter units, but before any secondary or custom units. See libflitter/Unit for more information on how to add functionality to the unit.

Example: Adding the express-graphql Middleware

As an example, we'll configure the underlying Express app to use the express-graphql package on the route /graphql. To do this, modify the app/MiscUnit.js file:

const Unit = require('libflitter/Unit')

class MiscUnit extends Unit {
    go(app, next){
      	// Get the GraphQL package
        const graphqlHTTP = require('express-graphql')
        // Tell the underlying express middleware to use it
        app.use('/graphql', graphqlHTTP({
            schema: MyGraphQLSchema,
            graphiql: true
    provides() {
        return {
            name: "misc"


module.exports = exports = MiscUnit

Here, we modify the go() method. This method is passed an instance of the underlying Express application (instance of express), which we can then use it as always.

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