C-View Markup

C-View Markup is a small markup language for describing console screens inside .cvw views: text, boxes, tables, form inputs, choice lists, checkboxes and menus. It compiles to plain C# at build time, so there is no runtime template parsing, and it mixes freely with ordinary C# code.

@model MyApp.Models.DashboardViewModel

<box title="Dashboard" border="double" color="cyan" width="60">
    <text align="centre" bold>Welcome, @Model.UserName!</text>
    <separator />
    @foreach (var notification in Model.Notifications)
    {
        <text>• @notification</text>
    }
</box>

Console.Write("Press Enter to continue...");
Console.ReadLine();
return NavigationResult.ToAction("Index");

Output (colours omitted):

╔═ Dashboard ══════════════════════════════════════════════╗
║                      Welcome, Ada!                       ║
║ ──────────────────────────────────────────────────────── ║
║ • Your report is ready                                   ║
║ • 3 new messages                                         ║
╚══════════════════════════════════════════════════════════╝
Press Enter to continue...

Backwards compatible

Views written in plain C# keep working unchanged. Markup is only recognised where a C# statement could begin, at the start of the body or after ;, {, } or :, when < is directly followed by a known tag name. C# can never start a statement with <, so comparisons and generics such as a < b or List<string> are never mistaken for markup.

How markup and code interact

• Top-level elements are rendered immediately, in source order. A <box> written before Console.ReadLine() appears before the prompt.
• The view still returns a NavigationResult from C# code.
• Inside an element, @ switches to C#:

Syntax	Meaning
@Model.Name, @items[0], @user?.GetName()	Implicit expression
@(a + b)	Explicit expression (use for anything with spaces or operators)
@if (…) { … } else { … }	Conditional content (also @foreach, @for, @while, @switch, @do, @try, @lock)
@{ var total = 0; }	Code block
@@	A literal @
name@example.com	@ after a letter or digit is literal, so e-mail addresses just work
@* comment *@, <!-- comment -->	Comments, removed at compile time
&lt; &gt; &amp; &quot; &apos; &nbsp; &at; &#64;	Character entities

Control flow and code blocks are allowed in containers such as <box> but not inside <text>; use an expression there instead, for example @(Model.IsAdmin ? "admin" : "user").

Preprocessor directives

#region, #if/#else/#endif, #pragma and other directive lines may be used in view code. Markup on the line after a directive is recognised as usual, so #if DEBUG around a <text> element works.

Reserved names

Generated code declares local variables starting with __cvw_; do not use that prefix for your own variables in views.

Whitespace

Text inside <text> follows HTML rules: runs of spaces and new lines collapse into a single space, and whitespace at the start and end is removed. Use <br /> for a line break. Values inserted with @expressions keep their own spaces and line breaks.

Security

Every value inserted into the screen is sanitised. Control characters, ANSI escape sequences and Unicode bidirectional overrides are removed, so model data typed by users cannot clear the screen, recolour the terminal or disguise text.

Elements

<text>

A block of text that wraps to the available width.

Attribute	Values	Default
color / colour	a colour	terminal default
background	a colour	terminal default
align	left, centre (or center), right	left
bold, dim, italic, underline	flag, or true/false	off
wrap	true to word-wrap, false to truncate with …	true
class	theme classes, separated by spaces	none

<text color="yellow" bold>Warning:</text>
<text align="right" dim>Page @Model.Page of @Model.PageCount</text>

<box>

A bordered panel. Its children are stacked vertically; text written directly inside a box becomes a <text> element automatically.

Attribute	Values	Default
title	text, may contain @expressions	none
width	auto, a column count (40), a percentage (50%), or * (all the width)	auto (fit the content)
border	single, double, rounded, heavy, ascii, none	single
padding	columns between border and content (0–20)	1
color / colour	border colour	terminal default
title-color / title-colour	title colour	border colour
min-width / max-width	column counts (0–1000) limiting the width	none
class	theme classes	none

Boxes never grow wider than the terminal; content wraps to fit. min-width widens a small box and max-width stops a width="100%" box growing on a wide terminal; the terminal width always wins.

<separator />

A horizontal rule that fills its container (or the terminal at top level).

Attribute	Values	Default
style	single, double, heavy, dashed, ascii	single
color / colour	a colour	terminal default
width	auto (fill), a column count, or a percentage	auto
class	theme classes (the text colour is used)	none

<br />

One or more empty lines between blocks, or a line break inside <text>.

Attribute	Values	Default
count	number of line breaks (0–100)	1

<table>, <row> and <cell>

A grid whose columns size themselves to the content. When the table is wider than the terminal, the widest columns shrink and their cells wrap. Rows are usually generated with @foreach.

<table border="rounded">
    <row header>
        <cell>Name</cell>
        <cell align="right">Age</cell>
    </row>
    @foreach (var user in Model.Users)
    {
        <row>
            <cell>@user.Name</cell>
            <cell align="right">@user.Age</cell>
        </row>
    }
</table>

╭───────┬─────╮
│ Name  │ Age │
├───────┼─────┤
│ Ada   │  36 │
│ Linus │  54 │
╰───────┴─────╯

Element	Attribute	Values	Default
<table>	border	single, double, rounded, heavy, ascii, none	single
	padding	blank columns on each side of every cell (0–20)	1
	width	auto, a column count, or a percentage; a larger width widens the last column	auto
	color / colour	grid colour	terminal default
	min-width / max-width	column counts limiting the width	none
	class	theme classes	none
<row>	header	flag: bold cells (unless a cell sets its own decoration) followed by a separator line	off
<cell>	same as <text>	align, color, background, bold, dim, italic, underline, wrap, class

A <table> may only contain <row> elements, and a <row> only <cell> elements; loops and conditions around them are fine. Rows with fewer cells are padded with empty cells.

<columns> and <column>

Places content side by side. Each <column> holds block content, like a box without a border.

<columns gap="2" stack-below="60">
    <column width="30%">
        <box class="panel" title="Menu"><text>[1] Orders</text></box>
    </column>
    <column>
        <text class="title">Orders</text>
        <text>@Model.Summary</text>
    </column>
</columns>

Element	Attribute	Values	Default
<columns>	gap	spaces between columns (0–20)	2
	stack-below	a width in columns: narrower terminals stack the columns vertically	never stack
<column>	width	auto, a column count, a percentage of the width after the gaps, or * for what the other columns leave	auto

• Fixed and percentage columns take their width first; auto columns use their content's natural width when it fits; * (fill) columns share what is left, so <column width="*"> followed by an auto column puts the second one at the right edge. Otherwise narrow columns keep their width and wide ones share the rest equally, wrapping their text.
• Columns can be generated with @foreach, nested in a <box>, and contain any block elements, including other columns.
• <columns> may only contain <column> elements, and <column> only appears inside <columns>.

<input>

Prompts for a value and stores it in the view's Form dictionary under its name. Post the form to a controller action, where it is bound to parameters or a model just like before:

<input name="Name" label="Name: " required />
<input name="Password" label="Password: " masked />
<input name="Colour" label="Favourite colour: " default="blue" />

return NavigationResult.ToAction("Result", Form);

Attribute	Values	Default
name	required: the key in Form (matched case-insensitively when binding)
label	the prompt written before reading	none
default	used when the user enters nothing	empty
required	flag: ask again until a value is entered	off
masked	flag: hide typed characters (shows one * per character); for passwords and other secrets. Backspace works, and Ctrl+D (or Ctrl+Z on Windows) on an empty line ends the input	off
color / colour	label colour	terminal default

Values are trimmed. Form is also available to ordinary C# in the view, for example int.Parse(Form["Age"]).

<select>, <radio> and <choice>

Offer a fixed list of answers. The answer is stored in Form like an <input>, so it posts and binds the same way. <select> lists the choices one under another (and may allow several answers); <radio> shows a short list side by side.

<select name="Colour" label="Favourite colour:" default="green">
    <choice value="red">Red</choice>
    <choice value="green">Green</choice>
    <choice value="blue">Blue</choice>
</select>

<select name="Toppings" label="Toppings:" multiple>
    @foreach (var topping in Model.Toppings)
    {
        <choice value="@topping.Id">@topping.Name</choice>
    }
</select>

<radio name="Size" label="Size:" default="M"><choice>S</choice><choice>M</choice><choice>L</choice></radio>

In a terminal the user answers with the keys; the field is redrawn in place and collapses to its answer:

Favourite colour: (Up/Down, Enter)        Size: ( ) S  (*) M  ( ) L  (Left/Right, Enter)
   Red
 > Green                                  Toppings: (Up/Down, Space, Enter)
   Blue                                    > [x] Cheese
                                             [ ] Ham
after Enter:  Favourite colour: Green

Key	Does
Up/Down (Left/Right, Tab, Home, End)	move the highlight; it wraps around
1 to 9	jump to that choice
Space	tick or untick the highlighted choice (multiple only)
Enter	confirm; a single choice is the highlighted one
Ctrl+D (Ctrl+Z on Windows)	end the input

When input is piped, in tests, or when the console cannot move the cursor, the choices are numbered instead and the user types a number, a value or a label (case-insensitive). Several answers are separated by commas (1,3). An empty answer takes the default:

Favourite colour:
  1) Red
  2) Green
  3) Blue
Choose 1-3 [Green]: _

Element	Attribute	Values	Default
<select>, <radio>	name	required: the key in Form
	label	the text before the choices; leading spaces indent the whole field	none
	default	the value chosen for an empty answer and highlighted first; for multiple, values separated by commas	none
	required	flag: an empty answer (no tick, for multiple) is asked again	off
	color / colour	label colour	terminal default
	highlight-color / highlight-colour	colour of the > marker	cyan
<select>	multiple	flag: several choices may be ticked; the answer is their values separated by commas, in the order of the choices	off
	filter	flag: typing narrows the list in a terminal (Backspace and Esc edit the filter); a typed answer may be part of a name that matches one choice	off
	size	how many choices a terminal shows at once; the list scrolls with the highlight and PageUp/PageDown move a page	all
<choice>	value	what the form receives	the label text
	style attributes	as for <text>

A multiple answer binds to string[], List<int>, IReadOnlyList<MyEnum> and other collections (see Model binding), so its values cannot contain commas. A field without choices (for example built from an empty list) throws an InvalidOperationException when it is shown; two choices with the same value are an ArgumentException.

<number /> and <date />

Ask for a number or a date, checked against a range. The answers are stored in the invariant culture (2.5, 2026-10-27), so they bind to int, decimal, double, DateOnly and DateTime.

<number name="Qty" label="Quantity:" min="1" max="99" decimals="0" default="1" />
<number name="Price" label="Price:" min="0" decimals="2" step="0.5" />
<date name="Due" label="Due:" min="today" max="today+90" default="today+7" />

Terminal:  Quantity: 1  (Up/Down, type a number, Enter)
           Due: 2026-11-03 Tue  (Left/Right, Up/Down, t today, Enter)
Typed:     Quantity: _      (a number with a dot for decimals; Enter a number from 1 to 99. if it is out of range)
           Due: _           (2026-11-03, today, tomorrow, yesterday, +7 or -1)

Element	Attribute	Values	Default
both	name	required: the key in Form
	label	the text before the value (a space is added if it has none)	none
	required	flag: an empty answer is asked again	off
	color / colour, highlight-color / highlight-colour	label colour; colour of the value being edited	terminal default; cyan
<number>	default	the answer to an empty line and the starting value	none
	min, max	the range, e.g. min="0" max="130" or max="@Model.Limit"	none
	step	how much Up/Down change the value (PageUp/PageDown change it by ten steps)	1
	decimals	the most decimal places; 0 for whole numbers	any
<date>	default, min, max	2026-10-27, today, today+N or today-N (checked at build time)	none; the terminal starts today

In a terminal, digits replace the number (the first one replaces the starting value), Backspace edits it and Esc restores the default. A date's Up/Down change the part chosen with Left/Right, and the date never leaves its range. DateElement.Clock decides what today is, so tests can fix it.

<checkbox />

Asks a yes/no question. The answer is "true" or "false" and binds to a bool.

<checkbox name="Newsletter" label="Send me the newsletter" />
<checkbox name="Terms" label="I accept the terms" required />

Terminal:   [ ] Send me the newsletter  (Space, Enter)       Space ticks, Enter confirms, y or n answer at once
Typed:      Send me the newsletter? [y/N]: _                 y, yes, true, 1 or n, no, false, 0

Attribute	Values	Default
name	required: the key in Form
label	the text beside the box (a ? is added to the typed question unless it ends in punctuation)	none
checked	flag: ticked at first, and the answer to an empty line	off
required	flag: the box must be ticked to continue (This box must be ticked.)	off
color / colour	label colour	terminal default

<menu> and <option>

Shows keyed choices, reads the user's choice, repeats until it is valid, and navigates. A menu replaces the usual "write the options, Console.ReadLine(), switch" code, so it ends the view: no return is needed.

<menu key-color="cyan">
    <option key="1" nav="Home/About">About</option>
    <option key="2" nav="Search" post>Search with the form above</option>
    <option key="q" quit>Exit</option>
</menu>

[1] About
[2] Search with the form above
[q] Exit
Select an option: _

Element	Attribute	Values	Default
<menu>	prompt	the prompt text	Select an option:
	error	message after an invalid choice	Invalid choice, please try again.
	key-color / key-colour	colour of the [key] labels	terminal default
<option>	key	required: what the user types (case-insensitive)
	nav	Controller/Action, or Action on the current controller, optionally with route values: Orders/Details?id=@order.Id (values from expressions are URL-escaped)
	quit	flag: quit the application
	back	flag: return to the previous screen (on the first screen, it is shown again)
	post	flag: post the view's Form with the navigation	off
	style attributes	as for <text>

Literal nav targets are checked when you build: nav="Orders/Detials" gives warning CVW119 naming the actions Orders has. Targets with an @ expression are only known at run time and are not checked. Make the warning an error with dotnet_diagnostic.CVW119.severity = error in .editorconfig.

Each option needs exactly one of nav, quit or back. Options can be generated in a loop, e.g. <option key="@(i + 1)" nav="Users/Details">@user.Name</option>. If the input ends (for example when piping input to the application), the menu quits instead of waiting forever.

Top level only

<input>, <number>, <date>, <select>, <radio>, <checkbox>, <menu>, <scroll> and <partial> run at the point they appear in the view's code, so they must be written at the top level of the view. They may be inside a C# if or loop there, but not inside a <box> or another element.

<breadcrumbs />

Shows where the user is, from the navigation history: Home › Orders › Details. Each screen is labelled with its controller for an Index action, else its action; the current one is bold. When the trail is too wide the oldest items become …, so the current screen always shows. It renders nothing outside an application (for example in a unit test).

<breadcrumbs class="muted" />
<breadcrumbs separator=" / " color="darkgrey" />

Attribute	Values	Default
separator	text between items	›
color / colour	a colour	terminal default
class	theme classes	none

Views can also read the history in C#: NavigationHistory (the routes, oldest first) and Breadcrumbs (the labels).

<shortcuts />

Lists the application's keyboard shortcuts that have a description, on one line: F1 Help Esc Back Ctrl+X Quit. Shortcuts that do not fit are left out from the end, and nothing is drawn when there are none. A layout is a good place for it. See Keyboard shortcuts.

Attribute	Values	Default
separator	text between shortcuts	two spaces
color / colour	description colour	terminal default
key-color / key-colour	key colour (keys are bold)	terminal default
class	theme style	none

<progress />

A progress bar on one line: Import ████████░░░░░░░░ 50%. Draw it in a view to show how far something has got, or keep it up to date while an action works with a live region.

<progress label="Disk " value="@Model.Used" max="@Model.Size" bar-width="30" class="success" />

Attribute	Values	Default
value	how much is done, a number or an expression; clamped to 0 to max	0
max	the value at which the bar is full	100
label	text before the bar; shortened first when the line is narrow	none
bar-width	width of the bar in columns	fills the line
percent	false hides the percentage	shown
style	block (██░░), line (━━──), ascii (##--)	block
color / colour	colour of the done part	terminal default
empty-color / empty-colour	colour of the part still to do	terminal default
label-color / label-colour	colour of the label and the percentage	terminal default
class	theme style (its colour colours the bar)	none

A max of 0 or less, or a value that is not a number, draws an empty bar.

<spinner />

A spinner and its label: ⠋ Connecting. It turns while it is in a live region; drawn in a view, it shows the frame you give it.

<spinner label="Waiting for the printer" />
<spinner label="Printed" done />                         ✓ Printed

Attribute	Values	Default
label	text after the spinner	none
style	dots (⠋⠙⠹…), line (a turning line in plain ASCII), circle (◐◓◑◒)	dots
frame	the frame to show, any whole number (it wraps), e.g. @DateTime.Now.Second	0
done	show the done symbol instead of a frame	off
done-symbol	what done shows	✓
color / colour	spinner colour	terminal default
label-color / label-colour	label colour	terminal default
class	theme style	none

<bar-chart> and <bar />

A horizontal bar chart: one bar per line, with its label and value. Bars are scaled to max (or the largest value) and fill the width; with the block style, a bar ends in eighths of a cell, so small differences still show.

<bar-chart format="N0" color="cyan">
    @foreach (var day in Model.Days)
    {
        <bar label="@day.Name" value="@day.Sales" />
    }
</bar-chart>

Mon ██████████████████████████████████▌            1,240
Tue ████████████████████▊                            750
Wed ██████████████████████████████████████████████ 1,810

<bar-chart> attribute	Values	Default
max	the value of a full bar	the largest value
values	false hides the values after the bars	shown
format	a .NET number format such as N0 or 0.0	0.##
style	block (with eighths), shade (▓▓▓), ascii (###)	block
color / colour	bar colour	terminal default
label-color / label-colour	label and value colour	terminal default
class	theme style (its colour colours the bars)	none

<bar /> attribute	Values	Default
value	required: a number or an expression; below 0 draws an empty bar
label	text before the bar; labels take at most a third of the width	none
color / colour	this bar's colour	the chart's

<bar> only goes inside <bar-chart>, and a chart holds only bars (and C# such as @foreach around them).

<sparkline />

A series of values on one line, one cell each: ▁▂▄▆█▆▄▂. When there are more values than fit, the most recent ones are shown.

<sparkline label="Queue " values="@Model.QueueHistory" show-last />     Queue ▁▂▂▃▅▇█▆▄▃▂▁ 3
<sparkline values="3, 5, 2, 8" />                                       ▃▄▁█

Attribute	Values	Default
values	required: numbers separated by commas or spaces, or an expression for a sequence of int, long, float, double or decimal
min / max	the values of the lowest and highest level	the smallest and largest value shown
label	text before the chart	none
show-last	show the latest value after the chart	off
format	a .NET number format for the latest value	0.##
color / colour	chart colour	terminal default
label-color / label-colour	label and value colour	terminal default
class	theme style	none

Values that are not finite numbers (double.NaN) leave a gap.

<markdown />

Draws Markdown for the terminal: help pages, release notes, descriptions from a database.

<markdown text="@Model.ReleaseNotes" />
<markdown text="@File.ReadAllText(Path.Combine(AppContext.BaseDirectory, "help.md"))" />

Markdown	Drawn as
# Heading to ###### Heading	bold (the first level also underlined)
paragraphs	wrapped to the width; two trailing spaces or \ at the end of a line break it
- item, * item, 1. item	• or the number with a hanging indent; indent by two spaces to nest
> quote	│ before each line
fenced code (```)	the lines as written, indented, clipped rather than wrapped
---	a rule across the width
**bold**, *italic*, `code`	styled, without the markers; \* is a literal star
[text](https://…), <https://…>	the text, underlined, followed by the address

Attribute	Values	Default
text	required: the Markdown, usually an expression
links	false hides link addresses	shown
heading-color / heading-colour	heading colour	terminal default
code-color / code-colour	code colour	yellow
link-color / link-colour	link colour	terminal default
quote-color / quote-colour	quote and rule colour	dark grey
class	theme style (its colour colours the headings)	none

Everything is sanitised, so Markdown from users cannot send terminal escape sequences, and unusual input cannot slow the screen down. HTML, tables and images are shown as text.

<scroll>

Shows long content a page at a time. In a terminal the user scrolls with the arrow keys (or J and K), Page Up and Page Down (or B and Space), Home and End, and continues with Enter, Esc or Q; the page they end on stays on the screen and the view goes on below it. When the content fits, or input or output is piped, everything is drawn at once.

<scroll height="15">
    @foreach (var entry in Model.Log)
    {
        <text>@entry</text>
    }
</scroll>

12:00:01 Started
12:00:04 Connected to the database
…
Lines 1-15 of 240  ↑↓ PgUp PgDn Home End  Enter continues

Attribute	Values	Default
height	lines per page, 1 to 1000	the window height less 3 rows
color / colour	colour of the status line	dark grey
class	theme style (its colour colours the status line)	none

Like a field, <scroll> waits for the user, so it goes at the top level of a view or partial, not inside <box> or <columns>. Any elements can go inside it.

<errors />

Shows validation messages from the view's ModelState (see Validation): every error, or only one field's errors with for. Renders nothing when there are no errors.

<errors />
<errors for="Email" color="yellow" />

• The Name field is required.
• The value 'twelve' is not valid for Age.

Attribute	Values	Default
for	a field name (case-insensitive)	all fields
class	theme class names, separated by spaces	none
color / colour	a colour	red

<partial />

Renders a partial view: a reusable piece of markup in Views/Shared/{Name}.cvw. Partials are compiled like views but cannot navigate, so they contain no <menu> and need no return.

@* Views/Shared/Header.cvw *@
@model string
<box border="double"><text align="centre">@Model</text></box>
<br />

@* Views/Home/IndexView.cvw *@
<partial name="Header" model="@Model.Title" />
<partial name="Footer" />

Attribute	Values	Default
name	the partial's file name, written literally (required)
model	an expression (@Model.User) or literal text (passed as a string)	none

• A file in Views/Shared that contains <body /> is a layout, not a partial.
• The partial is checked when you build: an unknown name (CVW114) lists the available partials, a partial with @model needs a model attribute (CVW115), and a model of the wrong type is a compiler error in the view that passes it.
• A partial shares the view's Form, ModelState, ViewData, renderer and input: an <input> in a partial fills the view's form, and <errors /> shows the view's errors.
• Partials may use @inject, C# code and other partials (a partial cannot render itself: CVW116).
• Like <input>, <partial> is written at the top level of the view (it may be inside a C# if or loop), not inside another element.

Refreshing with @refresh

@refresh 5s at the top of a view draws it again every 5 seconds (the action runs again for fresh data) until the user starts typing. The interval takes ms, s or m, from 100ms to 24 hours. See Live Screens.

Layouts and <body />

A layout frames every screen. It is a .cvw file in Views/Shared with a <body /> placeholder where the view goes:

@* Views/Shared/_Layout.cvw *@
<text class="muted" align="right">My App</text>
<body />
<separator class="muted" />

• Views/Shared/_Layout.cvw is used by every view. A view picks another with @layout Plain, or none with @layout none.
• The part before <body /> is drawn before the view. The part after it is drawn just before the view first waits for the user (its first <input>, <select>, <radio>, <checkbox> or <menu>), or when the view returns if it never waits. A console screen ends where it waits, so this is where a footer is seen: between the content and the menu.
• A layout shares the view's ViewData, ModelState, Form, theme and services, and may use C# and @inject. It runs before the view's own code, so it sees ViewData set by the controller. It has no @model.
• <body /> appears once, at the top level of the layout, not inside an element or a C# block. Partials have no layout, and layouts cannot nest.

Themes and class

A theme defines named styles once for the whole application; elements use them with class, like CSS classes:

<text class="title">Orders</text>
<box class="panel" title="Summary">…</box>
<text class="muted danger">Payment overdue</text>

Built-in class	Style
title	bold cyan text
muted	dim text
success / warning / info	green / yellow / blue text
danger	bold red text
panel	rounded cyan border, padding 2

Classes are applied in order, then the element's own attributes, so <box class="panel" padding="0"> keeps the panel's border with no padding. Unknown class names are ignored. Text properties apply to <text>, <cell>, <option> and <choice>; the text colour also colours <separator> and <errors>; border, padding and width properties apply to <box> and <table>.

Define your own classes, or replace the built-in ones, in Program.cs:

builder.Theme
    .Set("brand", new ThemeStyle { Foreground = Colour.Magenta, Bold = true })
    .Set("panel", new ThemeStyle { Border = BorderStyle.Double, BorderColour = Colour.Magenta, Padding = 1 });

builder.Theme = Theme.Empty; // or start with no classes at all

class accepts expressions: <text class="@(order.Late ? "danger" : "success")">. Partials use the same theme as the view that renders them.

Attribute values

• Literal values (width="40", border="double") are validated when you build. A typo such as colour="purpel" is a compile error pointing at the attribute.
• Expressions (width=@Model.Width, title="@Model.Name's account") are type-checked by the C# compiler. Expressions can be mixed with text only in text attributes such as title.

Colours

The 16 console colours by name: black, darkblue, darkgreen, darkcyan, darkred, darkmagenta, darkyellow, grey, darkgrey, blue, green, cyan, red, magenta, yellow, white. Both grey and gray are accepted, and dashes are ignored (dark-grey). Hex values such as #f80 and #ff8800 use 24-bit colour where the terminal supports it and the nearest console colour otherwise.

Colour output is automatically disabled when output is redirected, when the NO_COLOR environment variable is set, or when TERM=dumb.

Compile-time diagnostics

Mistakes in markup are reported as build errors located in the .cvw file. C# errors inside views are also mapped back to the right .cvw line and column.

Id	Meaning
CVW001	The .cvw file is not at Views/{Controller}/{Action}View.cvw (warning; the file is skipped)
CVW002	A folder or file name is not a valid C# identifier
CVW003	The file name does not end with View, so the router cannot find it (warning)
CVW004	Two views generate the same class (for example Views/Home and Views/home, or an Areas/X/Views/Home copy); the later file is skipped
CVW005	The project's RootNamespace is not a valid C# namespace (set <RootNamespace> in the project file)
CVW006	@model is declared more than once; the last one is used (warning)
CVW007	@inject without a type and a property name, or an invalid or reserved name (see Dependency Injection)
CVW008	Two @inject directives declare the same property name
CVW009	A partial view file is named Render, the name of its own method
CVW010	@refresh with an interval that is not a number with ms, s or m from 100 ms to 24 hours, used twice, or used in a partial view or a layout
CVW100	Unknown attribute
CVW101	Invalid attribute value
CVW102	Missing or mismatched closing tag
CVW103	Element not allowed here (e.g. <box> inside <text>, <row> outside <table>, <choice> outside <select> or <radio>, <menu> inside <box> or in a partial view)
CVW104	Unterminated expression, string, comment or block
CVW105	Unknown element (write &lt; for a literal <)
CVW106	Control flow or a code block inside <text>
CVW107	Attribute specified twice
CVW108	Malformed tag
CVW109	Element rule broken (an <option> needs exactly one of nav, quit or back)
CVW110	Text or an expression directly inside <table>, <row> or <menu>
CVW111	Required attribute missing (<option key>, name on <input>, <select>, <radio>, <checkbox>, <number>, <date> and <partial>, <bar value>, <sparkline values>, <markdown text>)
CVW112	@() contains no expression
CVW113	Markup nested more than 100 levels deep
CVW114	<partial> names no partial view in Views/Shared, or its name is not written literally
CVW115	A partial that declares @model is used without a model attribute
CVW116	A partial view renders itself
CVW117	<body /> outside a layout in Views/Shared, used twice or inside a C# block; or a layout with @model or @layout
CVW118	@layout names no layout (lists the available ones), or a partial uses @layout
CVW119	Warning: a literal nav target names a controller or action that does not exist (lists the ones that do)
CVW120	Warning: RedirectToAction, NavigationResult.To or NavigationResult.ToAction in C# names a controller or action that does not exist
CVW121	Warning: View("Name"), or View() in an action, has no view; the IDE offers Create view Views/{Controller}/{Name}View.cvw

Resizing the terminal

Elements are laid out to the terminal's width when they are drawn. When the window is resized, the framework clears the screen and lays the current screen out again at the new width, so a table re-wraps inside its borders instead of breaking onto new lines, and a wider window gives boxes and columns more room. Prompts and the answers already typed are shown again, and the cursor returns to the prompt that is waiting.

• This works on macOS, Linux and Windows terminals, a moment after the window stops changing size.
• A screen that also writes with Console.WriteLine is not redrawn, because that output cannot be laid out again; it stays as the terminal shows it.
• Characters typed at a prompt but not yet confirmed with Enter are kept, but appear again only after Enter.
• A <select>, <radio> or <checkbox> being answered with the arrow keys is redrawn with its current highlight and ticks.
• To turn it off: builder.Renderer = MarkupRenderer.CreateForConsole(redrawOnResize: false);

Rendering outside views

The elements are ordinary classes in the ConsoleMVC.Rendering namespace, which has no dependency on the MVC framework. You can use them directly:

using ConsoleMVC.Rendering;

var box = new BoxElement { Title = "Status", Border = BorderStyle.Rounded };
var text = new TextElement { Foreground = Colour.Green };
text.AppendText("All systems operational");
box.Add(text);

MarkupRenderer.CreateForConsole().Render(box);

To change how an application renders (for example to write plain text at a fixed width in tests) set MvcApplicationBuilder.Renderer. To drive it with scripted input, set MvcApplicationBuilder.Input to your own ITextInput:

builder.Renderer = new MarkupRenderer(new PlainTextRenderTarget(writer), () => 60);
builder.Input = new ScriptedInput("1", "Ada", "q"); // your ITextInput implementation

Interactive elements work outside views too:

var name = new InputElement { Name = "Name", Label = "Name: ", Required = true };
string? value = name.Read(renderer, ConsoleTextInput.Instance);

var size = new RadioElement { Name = "Size", Label = "Size:" };
foreach (var label in new[] { "S", "M", "L" })
{
    var choice = new ChoiceElement();
    choice.AppendText(label);
    size.Add(choice);
}
string? chosen = size.Read(renderer, ConsoleTextInput.Instance);

Arrow keys are used when ITextInput.CanReadKeys and IMarkupRenderer.CanRewrite are both true; a scripted ITextInput can return keys from ReadKey to test that mode, and IRenderTarget.TryEraseLines lets your own render target support it.