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API contract 3.4

Providers

Providers are the seams of the library. Three of them connect it to a backend — authentication, data and schemas — four are registries through which you replace generated UI with your own components, either globally or for a single resource, and one maps the backend's validation rules to the validators that enforce them.

PageWhat it covers
Auth providerLogin, logout, identity, MFA and password flows
Data providerCRUD calls, actions, search and aggregations
Schema providerFetching service, record and aggregate schemas
Field providerReplacing a display component
Input providerReplacing a form input
Button providerReplacing an action button
Box providerReplacing a layout container
Validator providerMapping a schema validation rule to a validator

How an override is resolved​

The four registries all work the same way. Habarico asks, in order:

  1. the resource's provider, passed to SchemaResource,
  2. the admin-wide provider, passed to SchemaAdmin,
  3. the built-in default*Provider.

A provider returns one of three things:

ReturnedMeaning
an elementRender it — the search ends here
undefined“Not mine” — hand the decision to the next step
nullRender nothing — the search ends here too

so an override only has to name the cases it actually cares about.

caution

null is not the same as undefined. Returning null suppresses the field, input, box or button altogether; only undefined falls through to the next provider. An implicit return in a provider yields undefined, which is what you want — an explicit return null hides the element.

tip

Match on the narrowest thing that identifies your case — usually source plus resource, or a format you introduced on the backend. Matching on type alone replaces the component for every field of that type in the whole admin.

One further registry follows the same pattern but lives in habarico-enterprise, with the feature it serves: the widget catalogue behind dashboard widget types.

The validator provider answers the same three ways but resolves in two steps, not three: it has no per-resource variant, so a rule it declines falls straight through to defaultValidatorProvider. It also returns a validator function rather than an element.

See also​