This module contains a React version of the DataHub UI, which is currently under incubation. Notice that this is a completely separate frontend experience from Ember and will remain so as it evolves.

Feel free to take a look around, deploy, and make contributions.

For details about the motivation please see this RFC.

Functional Goals

The initial milestone for the app is to achieve functional parity with the existing Ember app. This means supporting

Dataset Profiles, Search, Browse Experience
User Profiles, Search
LDAP Authentication Flow

Design Goals

In building out a new client experience, we intend to build on learnings from the Ember app and incorporate feedback gathered from organizations operating DataHub. Two themes have emerged to serve as guideposts:

Configurability: The client experience should be configurable, such that deploying organizations can tailor certain aspects to their needs. This includes theme / styling configurability, showing and hiding specific functionality, customizing copy & logos, etc.
Extensibility: Extending the functionality of DataHub should be as simple as possible. Making changes like extending an existing entity & adding a new entity should require minimal effort and should be well covered in detailed documentation.

Starting the Application

Quick Start

Navigate to the docker directory and run the following to spin up the react app:

./quickstart-react.sh

at http://localhost:9002.

If you want to make changes to the UI see them live without having to rebuild the datahub-frontend-react docker image, you can run the following in this directory:

yarn install && yarn run start

which will start a forwarding server at localhost:3000. Note that to fetch real data, datahub-frontend server will also need to be deployed, still at http://localhost:9002, to service GraphQL API requests.

Design Details

Package Organization

The organization is yet subject to change as the app incubates. As of today (2/11/2021), the src dir of the app is broken down into the following modules

conf - Stores global configuration flags that can be referenced across the app. For example, the number of search results shown per page, or the placeholder text in the search bar box. It serves as a location where levels for functional configurability should reside.

components - Contains all important components of the app. It has a few sub-modules:

auth: Components used to render the user authentication experience.
browse: Shared components used to render the 'browse-by-path' experience. The experience is akin to navigating a filesystem hierarchy.
preview: Shared components used to render Entity 'preview' views. These can appear in search results, browse results, and within entity profile pages.
search: Shared components used to render the full-text search experience.
shared: Misc. shared components
entity: Contains Entity definitions, where entity-specific functionality resides. Configuration is provided by implementing the 'Entity' interface. (See DatasetEntity.tsx for example) There are 2 visual components each entity should supply:
- profiles: display relevant details about an individual entity. This serves as the entity's 'profile'.
- previews: provide a 'preview', or a smaller details card, containing the most important information about an entity instance.
  
  When rendering a preview, the entity's data and the type of preview (SEARCH, BROWSE, PREVIEW) are provided. This allows you to optionally customize the way an entities preview is rendered in different views.
- entity registry: There's another very important piece of code living within this module: the EntityRegistry. This is a layer of abstraction over the intimate details of rendering a particular entity. It is used to render a view associated with a particular entity type (user, dataset, etc.).

graphql - The React App talks to the dathub-frontend server using GraphQL. This module is where the queries issued against the server are defined. Once defined, running yarn run generate will code-gen TypeScript objects to make invoking these queries extremely easy. An example can be found at the top of SearchPage.tsx.

images - Images to be displayed within the app. This is where one would place a custom logo image.

Adding an Entity

The following outlines a series of steps required to introduce a new entity into the React app:

Declare the GraphQL Queries required to display the new entity
- If search functionality should be supported, extend the "search" query within search.graphql to fetch the new entity data.
- If browse functionality should be supported, extend the "browse" query within browse.graphql to fetch the new entity data.
- If display a 'profile' should be supported (most often), introduce a new <entity-name>.graphql file that contains a get query to fetch the entity by primary key (urn).
Note that your new entity must implement the Entity GraphQL type interface, and thus must have a corresponding EntityType.
Implement the Entity interface
- Create a new folder under src/components/entity corresponding to your entity
- Create a class that implements the Entity interface (example: DatasetEntity.tsx)
- Provide an implementation each method defined on the interface.
  - This class specifies whether your new entity should be searchable & browsable, defines the names used to identify your entity when instances are rendered in collection / when entity appears in the URL path, and provides the ability to render your entity given data returned by the GQL API.
Register the new entity in the EntityRegistry
- Update App.tsx to register an instance of your new entity. Now your entity will be accessible via the registry and appear in the UI. To manually retrieve the info about your entity or others, simply use an instance of the EntityRegistry, which is provided via ReactContext to all components in the hierarchy. For example
```
entityRegistry.getCollectionName(EntityType.YOUR_NEW_ENTITY)
```

That's it! For any questions, do not hesitate to reach out on the DataHub Slack community in #datahub-react.