PromptPlus

# PromptPlus ## **Select<T> — Operations** [![NuGet](https://img.shields.io/badge/NuGet-PromptPlus-blue)](https://www.nuget.org/packages/PromptPlus) [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT) [![.NET](https://img.shields.io/badge/.NET-8%20%7C%209%20%7C%2010-512BD4)](https://dotnet.microsoft.com/)

← Back to Home • Next: Select — Styles →

How the Select<T> control behaves while it is running: keyboard, filtering, grouping, paging, validation, history, and view-only mode.

Anatomy of the control

Which city? Seattle (Length: 7)          ← prompt + live answer (follows the cursor) + ExtraInfo
Type to filter                           ← description (optional / dynamic)
North America                            ← group header (grouped lists)
› Seattle            (Length: 7)         ← focused item + ExtraInfo
  New York           (Length: 8)
Asia
  Tokyo              (Length: 5)
Filter: to_                              ← live filter text (when filtering)
Page 1/2                                 ← pagination
Enter: confirm  Esc: cancel              ← tooltip

The answer line updates as you navigate and includes ExtraInfo/ExtraInfoAsync when set — useful when a row’s own text is too wide for the console and would otherwise be cut off, since this line scrolls horizontally (Home/End/←/→). Once confirmed (Enter), the final answer shown is the plain item text — no ExtraInfo.

Every region can be recolored — see Styles.

Keyboard

Key	Action
`↑` / `↓`	Move focus up / down
`Page Up` / `Page Down`	Jump one page
`Ctrl+Home` / `Ctrl+End`	First / last item
`Enter`	Confirm the focused item (runs validation)
`Esc`	Abort → `IsAborted == true`
Any printable character	Type to filter (when `Filter` is not `Disabled`)
`Backspace`	Edit the filter text
`Home` / `End` / `←` / `→`	Scroll the answer line horizontally (when it overflows the width)
`F1`	Cycle tooltip content
`Ctrl+F1`	Show / hide the tooltip

Disabled items and separators are skipped automatically as you move.

Filtering

When Filter is Contains or StartsWith, typing narrows the visible list in real time:

The match is case-insensitive.
Matching resets paging to the first page of results.
With AutoSelect, narrowing to a single selectable item confirms it immediately — no Enter required.
Clearing the filter (Backspace) restores the full list.

Disabled (the default) turns typing off entirely — arrow keys only.

Grouping & separators

AddGroupedItem / AddGroupedItems render a header above their items; the header repeats appropriately as the list scrolls.
A hint shows the group of the focused item — hide it with HideTipGroup.
AddSeparator draws a divider line (single, double, or a custom char). Separators are purely visual and are skipped during navigation.

Grouped and ungrouped items can be mixed in one list.

Item text & extra info

TextSelector decides the label; without it, ToString() is used and enum members honor their [Display(Name = ...)] attribute.
Enum ordering follows [Display(Order = ...)] when present.
ExtraInfo adds a secondary label per row, wrapped by the extra-info prefix/suffix (default ( ), configurable).

Confirmation & validation flow

Pressing Enter on the focused item:

Validation runs — PredicateSelected / PredicateSelectedAsync, if configured.
Valid → the control closes and returns the item. Invalid → the list stays open and shows the error line.

Disabled items cannot be focused for confirmation, so validation typically guards business rules (e.g., “this option is not available for your plan”) rather than availability.

Initial selection & history

Default(value) pre-highlights an item; provide DefaultMatchBy for records/classes so the right row is located.
With EnableHistory, confirmed selections are stored on disk; UseDefaultHistory (or Default(..., useDefaultHistory: true)) restores the last one on the next run.
History options (MinPrefixLength, MaxItems, ExpirationTime, FilterType, PageSize) match the Input history options.

View-only mode

ViewOnly() renders the list for display only:

Arrow keys still scroll, but items cannot be selected.
Combine with Default to highlight one entry.
Useful for showing a read-only snapshot inline with other prompts.
ViewOnly(true) silently disables AutoSelect and any configured history — even if you called EnableHistory/AutoSelect earlier in the chain, turning on ViewOnly overrides both. There’s no warning; if the list looks like it stopped auto-loading history, this is why.

Options that change behavior

Set per instance via Options(...), or globally on PromptPlus.Config:

Option	Effect on `Select<T>`
`EnabledAbortKey(false)`	Removes Esc — the user must choose
`HideAfterFinish(true)`	Erases the list after confirm — the whole control is erased, not just the interactive part
`ShowTooltip(false)`	Hides the keyboard hint line
`Prompt(...)` / `Description(...)`	Overrides the prompt / description text

PageSize can be set per control (PageSize) or globally (PromptPlus.Config.PageSize).

Edge cases & gotchas

Aborted results carry .Content == default(T) (e.g., null for reference types). Always branch on IsAborted.
Custom types need equality. Without DefaultMatchBy, Default on a record/class may not match the intended row.
Async callbacks block the UI thread — keep validators, selectors, and description callbacks fast.
Long labels are truncated to a single line with …; the full item is still returned in .Content.