openmrs-esm-module-config

What is this?

This is the configuration library for OpenMRS Microfrontends. It makes configurability easier for developers and configuring easier for implementers.

What does an OpenMRS frontend configuration file look like?
How do I configure my OpenMRS implementation?
I'm developing an ESM module. How do I make it configurable?
API
Contributing & Development

What does an OpenMRS frontend configuration file look like?

OpenMRS frontend configuration files are JSON files containing module names as top-level elements. All configuration elements are optional. The available configuration elements for each module should be documented in the module's wiki page.

Here's an example!

{
  "@openmrs/esm-login-app": {
    "logo": {
      "src": "https://pbs.twimg.com/media/C1w_czvWgAAWONL.jpg"
    }
  },
  "@openmrs/esm-home-app": {
    "buttons": {
      "enabled": false
    }
  }
}

Alternatively you can provide your config file as a Javascript file. It will look just about the same, but with some magic words at the beginning:

exports = {};
exports.default = {
  "@openmrs/esm-login-app": {
    logo: {
      src: "https://pbs.twimg.com/media/C1w_czvWgAAWONL.jpg"
    }
  },
  "@openmrs/esm-home-app": {
    buttons: {
      enabled: false
    }
  }
}

How do I configure my OpenMRS implementation?

There are two methods for doing so.

The Simple Way

Upload your configuration file and add its URL to your import map as a module named config-file. If you are serving your microfrontends from your OpenMRS server, you can simply add your config file to your server's frontend/ directory. Your import map will then look like

{
  "imports": {
    "config-file": "/openmrs/frontend/config.js[on]"
  }
}

The Flexible Way (under construction)

Due to RFC-26 this method will not work as described with openmrs-module-spa after 1.0.6. Please hang tight while we work out how to support hierarchal config files in the new architecture.

This method requires you have an esm-root-config override. This allows you to have multiple configuration files, which will be merged together in an order that you specify. You add your configuration files to your root override module, import them, and provide them to esm-module-config. All this must happen before you register your applications.

Example code:

import { provide } from "@openmrs/esm-module-config";

import pihConfig from "./pih-config.json";
import pihMexicoConfig from "./pih-mexico-config.json";

provide(pihConfig);
provide(pihMexicoConfig);

All provided configs will be merged, with elements provided by later calls to provide taking priority. The import map config file, config-file, will also be merged, and will take the lowest priority. In the above example, configuration elements in pih-mexico-config.json will take priority over those in pih-config.json.

You can break up your configuration files into hierarchies, or per module, or per groups of modules.

I'm developing an ESM module. How do I make it configurable?

You should use this module, esm-module-config, to make your modules configurable.

Start by npm install --save @openmrs/esm-module-config. This is a runtime dependency, so it should be included in your webpack externals.

The main task is to create a config schema for your module. The config schema is what tells esm-module-config what configuration files should look like, including defaults and validations.

Designing a schema

You'll probably start with some idea of what you want configs for your module to look like. Try and put yourself in the implementer's shoes an imagine what features they will expect to be configurable, and what they might expect the configuration property to be called. Assume they don't know anything about the internal workings of your module.

By way of example, let's say we're building a module for a virtual provider functionality at a very futuristic hospital. Maybe we want an implementer to be able to write the following in their config file:

"@openmrs/esm-hologram-doctor": {
  "hologram": {
    "color": true
  },
  "virtualProvider": {
    "name": {
      "given": ["Qui", "Gon"]
    }
  },
  "robots": [
    { "name": "R2-D2", "homeworld": "Naboo" },
    { "name": "BB-8", "homeworld": "Hosnian Prime" }
  ]
}

In the following section, we'll see how to write a config schema that supports these config elements.

Defining a schema

We'll start with just that first nested config element from above, hologram.color. We must provide defaults for all of the values—in OpenMRS Microfrontends, all configuration is optional.

import { defineConfigSchema, validators, validator } from "@openmrs/esm-module-config"

defineConfigSchema("@openmrs/esm-hologram-doctor", {
  hologram: {
    color: {
      default: false,
      validators: [validators.isBoolean],
      description: "Whether the cologram supports color display."
    }
  }
}

Note that each configuration element should have an object for a value, and that this object must define the default for that element. Do not do this:

❌ // This is wrong!
❌ defineConfigSchema("@openmrs/esm-hologram-doctor",
❌  hologram: {
❌   salutation: "Some friendly default salutation! ? this is wrong!"
❌ })

The following names are reserved and cannot be used as config keys: default, validators, description, and arrayElements. Doing so will result in undefined behavior. Do not do this:

❌ // Don't do this!
❌ defineConfigSchema("@openmrs/esm-hologram-doctor",
❌  hologram: {
❌    salutation: {
❌      default: {
❌        default: "Greetings ? this is bad don't do it"
❌ }}})

Validators

You should provide validators for your configuration elements wherever possible. This reduces the probability that implementers using your module will have hard-to-debug runtime errors. It gives you, the module developer, the opportunity to provide implementers with very helpful explanations about why their configuration on't work.

robot: {
  name: {
    default: "R2D2",
    validators: [
      validators.isString,
      validator(n => /\d/.test(n), "Robots must have numbers in their names")
    ]
  }
}

(Note that this piece of schema is not part of our above example. It only supports a single robot, whereas we need to allow the implementer to provide an array of robots).

A validator can be created using the validator function, as above.

The first argument is a function that takes the config value as its only argument. If the function returns something truthy, validation passes. If the function returns something falsy, an error is thrown with the second argument as an explanation.

You can even validate nested objects:

colorPicker: {
  options: { default: ["black", "red"] }
  initial: { default: "black" },
  validators: [
    validator(o => o.options.includes(o.initial),
      "initial must be one of the options")
  ]
}

For convenience, some common validators are provided out of the box. See the API / validators.

Arrays

You can accept and validate arrays, and arrays containing objects, in your configuration schema. This is configured with the arrayElements parameter. For example, a schema which would accept an array of strings:

virtualProvider: {
  name: {
    given: {
      default: ["Obi", "Wan"]
      arrayElements: {
        validators: [validators.isString]
      }
    }
  }
}

Here is an example of a schema that expects an array of objects structured in a particular way.

robots: {
  default: [
    { name: "R2-D2", homeworld: "Naboo" },
    { name: "C-3PO", homeworld: "Tatooine" }
  ],
  arrayElements: {
    name: { validators: [robotNameValidator] },
    homeworld: {
      default: null  // not required
      validators: [validators.isString]
    }
  }
}

This schema will require that any objects in the robots array must only have the keys name and homeworld.

Freeform objects

In unusual scenarios you might want to accept an object without validating its keys. To do this, you can specify the config element like a normal non-object element.

beepsPerRobot: {
  default: {
    "R2-D2": 4,
    "C-3P0": 0
  },
  validators: [  // you can (and should) still run validators
    validators.isObject,
    validator(o => Object.values(o).every(Number.isInteger),
      "robot beeps must be integers")
  ]
}

Using config values

The generic way

The config is fetched asynchronously using getConfig(moduleName). Continuing the above example, we would have something like

import { getConfig } from "@openmrs/esm-module-config"

async function doctorGreeting() {
  const config = await getConfig("@openmrs/esm-hologram-doctor")
  return "Hello, my name is Dr. " + config.virtualProvider.name.family
}

The content of config will be pulled from the config files, falling back to the defaults for configuration elements for which no values have been provided.

React support

A React Hook is provided to hide the asynchronicity of config loading. The moduleNameprovided to the openmrs react root decorator is used to look up the configuration elsewhere in the application.

export default openmrsRootDecorator({
  featureName: "hologram doctor",
  moduleName: "@openmrs/esm-hologram-doctor"
})(Root)

You can then get the config tree as an object using the useConfig React hook.

import { useConfig } from "@openmrs/esm-module-config"

export default function DoctorGreeting() {
  const config = useConfig()
  const greeting = "Hello, my name is Dr. " + config.virtualProvider.name.family
  return <div>{greeting}</div>
}

The content of config will be pulled from the config files, falling back to the defaults for configuration elements for which no values have been provided.

Support in other frameworks (Angular, Vue, Svelte, etc.)

This hasn't been implemented yet, but we would like to implement it! See "Contributing"

API

Variables

ModuleNameContext

Navigation Functions

Other Functions

Object literals

validators

Variables

`Const` ModuleNameContext

• ModuleNameContext: Context‹null | string› = React.createContext<string | null>(null)

Defined in react-hook/react-hook.tsx:4

Navigation Functions

ConfigurableLink

▸ ConfigurableLink(__namedParameters: object): Element‹›

Defined in navigation/react-configurable-link.tsx:13

A React link component which calls navigate when clicked

Parameters:

▪ __namedParameters: object

Name	Type	Description
`children`	any	Inline elements within the link
`otherProps`	otherProps	Any other valid props for an tag except `href` and `onClick`
`to`	string	The target path or URL. Supports interpolation. See navigate

Returns: Element‹›

interpolateString

▸ interpolateString(template: string, params: object): string

Defined in navigation/interpolate-string.ts:38

Interpolates values of params into the template string.

Useful for additional template parameters in URLs.

Example usage:

navigate({
 to: interpolateString(
   config.links.patientChart,
   { patientUuid: patient.uuid }
 )
});

Parameters:

Name	Type	Description
`template`	string	With optional params wrapped in `${ }`
`params`	object	Values to interpolate into the string template

Returns: string

navigate

▸ navigate(__namedParameters: object): void

Defined in navigation/navigate.ts:24

Calls location.assign for non-SPA paths and navigateToUrl for SPA paths

Example usage:

const config = getConfig();
const submitHandler = () => {
  navigate({ to: config.links.submitSuccess });
};

Parameters:

▪ __namedParameters: object

Name	Type	Description
`to`	string	The target path or URL. Supports templating with 'openmrsBase' and 'openmrsSpaBase'. For example, `${openmrsSpaBase}/home` will resolve to `/openmrs/spa/home` for implementations using the standard OpenMRS and SPA base paths.

Returns: void

Other Functions

defineConfigSchema

▸ defineConfigSchema(moduleName: string, schema: ConfigSchema): void

Defined in module-config/module-config.ts:20

Parameters:

Name	Type
`moduleName`	string
`schema`	ConfigSchema

Returns: void

getConfig

▸ getConfig(moduleName: string): Promise‹ConfigObject›

Defined in module-config/module-config.ts:29

Parameters:

Name	Type
`moduleName`	string

Returns: Promise‹ConfigObject›

processConfig

▸ processConfig(schema: ConfigSchema, providedConfig: ConfigObject, keyPathContext: string): Config

Defined in module-config/module-config.ts:42

Validate and interpolate defaults for providedConfig according to schema

Parameters:

Name	Type	Description
`schema`	ConfigSchema	a configuration schema
`providedConfig`	ConfigObject	an object of config values (without the top-level module name)
`keyPathContext`	string	a dot-deparated string which helps the user figure out where the provided config came from

Returns: Config

provide

▸ provide(config: Config, sourceName: string): void

Defined in module-config/module-config.ts:25

Parameters:

Name	Type	Default
`config`	Config	-
`sourceName`	string	"provided"

Returns: void

useConfig

▸ useConfig(): any

Defined in react-hook/react-hook.tsx:8

Returns: any

validator

▸ validator(validationFunction: ValidatorFunction, message: string): Validator

Defined in validators/validator.ts:1

Parameters:

Name	Type
`validationFunction`	ValidatorFunction
`message`	string

Returns: Validator

Object literals

`Const` validators

▪ validators: object

Type declaration:

▸ (value: any): void | string

Parameters:

Name	Type
`value`	any

Contributing & Development

PRs welcome! See OpenMRS Microfrontends RFC-20 for guidelines about contributing.

Setup local development environment for OpenMRS SPA.

Maintainer: Brandon Istenes (bistenes@pih.org)