Creating A Custom Injector

Injectors are what make Aida useful. The idea behind injectors is each injector in the pipeline "injects" a function of their own, thus enriching the model that was originally passed.

Rules and Conventions

• Each injector accepts two parameters:
  • models - you can access the models information, as well as injected functionality from previous injectors in the pipeline,
  • options - the various options your injector should take
• Each injector has to be pure (shouldn't modify the passed models or options).
• Each injector should default-export a single function (usually named main)
• The name of the property the injector "injects" into the returning object should match the name of the injector package (after the @aida/injector- part) in camelCase. For example @aida/injector-routes-map becomes routesMap.
• The injected property should have a single function named execute that accepts a single overriddenOptions object that can pass the same options as before in order to override them if desired by dependent injectors. This is why it is recommended that you make sure there are no name collisions between your options and the options accepted by your dependencies. The execute function will return the expected result for that injector.

Example

//This has to be default exported.
export default function main(models, options = {}) {
  return {
    ...models, //All models and everything the previous injectors in the pipeline have injected.
    myInjector: {
      //This property has to be called `execute`.
      execute: (overriddenOptions = {}) => {
        const mergedOptions = deepMerge(overriddenOptions, options) //You should deep merge the options here, using an imaginary function in this case.
        return myInjectorResults(mergedOptions); //This returns something useful for the user.
      },
    },
  };
}

Adding an injector to Aida

Injectors that are generic-enough can be added to the Aida monorepo. Simply create a pull request that adds your injector to the packages, along with unit tests, updated documentation in the website docs (in the reference for existing injectors), and a README.MD that follows some conventions in its formatting (check other injectors for a template).