Closures

Static config is fine until the field needs to know about the record, the user, or the weather on Mars. Orbit evaluates callables at render / validation time via almasix.orbit.support.evaluate.

Deep dive on the helper itself: Support closures.

What can be a callable?

On fields (and most components):

Surface	Example
`.label(...)`	`lambda record=None, **_: record["name"]`
`.helper_text(...)` / `.hint(...)`	Context-aware help
`.placeholder(...)`	Dynamic hint text
`.default(...)`	Prefill from request / tenant
`.options(...)`	Load choices lazily
`.visible(...)` / `.disabled(...)`	Show/hide or lock
`.required(...)`	Conditionally required

from almasix.orbit.forms import Select, TextInput

Select.make("assignee_id")
    .label(lambda **_: "Assignee")
    .options(lambda **ctx: load_assignees(ctx.get("tenant")))
    .visible(lambda record=None, **_: bool(record))
    .disabled(lambda user=None, **_: not getattr(user, "is_manager", False))

TextInput.make("slug")
    .required(lambda data=None, **_: bool((data or {}).get("publish")))
    .helper_text(lambda **_: "Locked after publish")

Passing context

Whatever you pass into field.render(state, **ctx) (or the form’s render) becomes keyword args for the callable:

form.render(form.get_state(), record=post, user=request.user, tenant=tenant)

Match parameter names to what you pass (record=, user=, …). Extra kwargs are fine — evaluate tries a few call shapes.

Options that aren’t static

Select.make("status").options({
    "draft": "Draft",
    "published": "Published",
})

# Same idea, deferred:
Select.make("status").options(lambda **_: fetch_statuses())

get_options(**ctx) always returns a plain dict.

Invisible ≠ deleted

.visible(False) (or a callable that returns false) skips HTML. Dehydration still respects .dehydrated() — hide chrome carefully if the value must round-trip.

Closures

What can be a callable?

Passing context

Options that aren’t static

Invisible ≠ deleted

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