@tum-mri-aiim/ra-data-fhir

FHIR REST Data Provider For React-Admin

FHIR REST Data Provider for react-admin. React-admin is a frontend framework for building admin applications. This dataProvider enables using a FHIR Rest Server with React-admin. The dataProvider was tested using an LinuxForHealth (formerly IBM FHIR Server).

Installation

npm install --save @tum-mri-aiim/ra-data-fhir

Testing

npm test

Demo

Find a demo application using this data provider and a demo FHIR server setup here.

REST Dialect

Method	API calls
getList	GET {baseURL}/{res}?{param=value}*
	GET {baseURL}/{res}?_summary=count&{param=value}*
getOne	GET {baseURL}/{res}/{id}
getMany	GET {baseURL}/{res}/_id={val1,val2,val3}
getManyReference	GET {baseURL}/{res}?target=value&{param=value}*
create	POST {baseURL}/{res} (id is returned by server in header)
update	PUT {baseURL}/{res}/{id}
updateMany	PUT {baseURL}/{res}/{id} (called multiple times)
delete	DELETE {baseURL}/{res}/{id}
deleteMany	DELETE {baseURL}/{res}/{id} (called multiple times)

Usage

See our example demo application for more information.

import * as React from "react";
import { Admin, Resource, ListGuesser, ShowGuesser } from 'react-admin';
import dataProvider from 'ra-fhir';
import { EMPTY_FHIR_EXTENDER } from 'ra-fhir';
import { fetchUtils } from "react-admin";

const fetchJson = (url, options = {}) => {
    if (!options.headers) {
        options.headers = new Headers({ Accept: 'application/json' });
    }
    return fetchUtils.fetchJson(url, options);
}

const dp = dataProvider('rest', fetchJson, EMPTY_FHIR_EXTENDER);

const App = () => {
    return (
        <Admin  dataProvider={dp}>
              ....
        </Admin>
    )
};

export default App;

Adding Custom Headers

The provider function accepts an HTTP client function as second argument. By default, they use react-admin's fetchUtils.fetchJson() as HTTP client. It's similar to HTML5 fetch(), except it handles JSON decoding and HTTP error codes automatically.

That means that if you need to add custom headers to your requests, you just need to wrap the fetchJson() call inside your own function:

import { fetchUtils, Admin, Resource } from 'react-admin';
import postgrestRestProvider from '@promitheus/ra-data-postgrest';

const httpClient = (url, options = {}) => {
    if (!options.headers) {
        options.headers = new Headers({ Accept: 'application/json' });
    }
    // add your own headers here
    options.headers.set('X-Custom-Header', 'foobar');
    return fetchUtils.fetchJson(url, options);
};
const dataProvider = postgrestRestProvider('http://localhost:3000', httpClient);

render(
    <Admin dataProvider={dataProvider} title="Example Admin">
        ...
    </Admin>,
    document.getElementById('root')
);

Now all the requests to the REST API will contain the X-Custom-Header: foobar header.

Tip: The most common usage of custom headers is for authentication. fetchJson has built-on support for the Authorization token header:

const httpClient = (url, options = {}) => {
    options.user = {
        authenticated: true,
        token: 'SRTRDFVESGNJYTUKTYTHRG',
    };
    return fetchUtils.fetchJson(url, options);
};

Now all the requests to the REST API will contain the Authorization: SRTRDFVESGNJYTUKTYTHRG header.

Filter Operators

As FHIR allows several comparators, e.g. ne, gt, eq... The dataProvider is designed to enable you to specify the filter operator in your react filter component:

<Filter {...props}>
    <TextInput label="Search" source="name_ne" alwaysOn />
    <TextInput label="Search" source="age_gt" alwaysOn />
    // some more filters
</Filter>

One can simply append the comparator with an _ to the source. In this example the field name would be filtered with not equal whereas age would be filtered using greater than. According to the FHIR standard, if no prefix is present, the prefix eq is assumed.

FHIR Extender

The FHIR Extender can extend and minimize FHIR resources by adding or removing certain default attributes and values. In FHIR's resources, there are a lot of optional parameters. Thus, on the react-admin application side, these object attributes could potentially miss which could lead to a list full of non-uniform objects. The FHIR Extender solves this issue by extending the objects with defined key-value pairs.

import { fetchUtils } from "react-admin";
import { EMPTY_FHIR_EXTENDER } from "@tum-mri-aiim/ra-data-fhir";

/**
 * Enable extending
 * The Patient resource is extended if the keys are absent.
 * E.g. if there is no deceasedDateTime the default will always be 01.01.1800
 */
EMPTY_FHIR_EXTENDER.addDefault("Patient", {
    name: [],
    address: [],
    deceasedDateTime: "1800-01-01",
});

const dp = dataProvider("rest", fetchUtils.fetchJson, EMPTY_FHIR_EXTENDER);

In this example, the Patient ressource is configured, to guarantee the fields name, address and deceasedDateTime with default values are present after a request.

Beware that in the other direction (from the app to the server), the data will be minimized, i.e. a Patient which would be inserted with the date 1800-01-01 ends up having no date. Thus, one should wisely select default values.

Limitations

The present data provider is currently limited to run flawlessly in combination with the LinuxForHealth FHIR server (former IBM FRHIR Server). Compatibility with the HAPI FHIR server is only given for read operations. Other FHIR servers, such as Blaze, were not tested yet. Please fell free to contribute concerning this compatibility. In future, we'd love to be the library to be compatible with many FHIR servers.

The current version of FHIR Extender cannot handle nested structures. There, it is currently required to create custom components. We plan to tackle this issue in future.

License

This data provider is licensed under the MIT License.