maui-data-binding

A guide to connecting .NET MAUI app screens to data and settings in C# code. It covers XAML, the markup used to describe MAUI screens, and the related C# patterns.

In plain words
What is it for?
Use it to connect controls to ViewModel properties, report property changes, convert values, choose one-way or two-way updates, and configure binding contexts.
Why use it?
It helps prevent screens from showing stale or incorrectly formatted data and catches many binding mistakes while building.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/managedcode/dotnet-skills/maui-data-binding
Any agent
npx skills add managedcode/dotnet-skills --skill maui-data-binding
Clone the repo
git clone --depth 1 https://github.com/managedcode/dotnet-skills

Made for: Claude Code, Codex.

Per session 180 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,556 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00180 $0.03556
Opus 5 $0.00090 $0.01778
Sonnet 5 $0.00036 $0.00711
Haiku 4.5 $0.00018 $0.00356

Measured yesterday against content hash 7fd85f91cf1e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

maui-data-binding scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

100% identical to maui-data-binding — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

catalog/Frameworks/Official-DotNet-MAUI/skills/maui-data-binding/SKILL.md · 422 lines

How it starts

The opening of the file, as written. The whole thing — 422 lines — stays where its author put it; the contents beside it link to each section on GitHub.

.NET MAUI Data Binding

Wire UI controls to ViewModel properties with compile-time safety, correct change notification, and minimal overhead. Prefer compiled bindings everywhere and treat binding warnings as build errors.

When to Use

  • Adding x:DataType compiled bindings to a new or existing page
  • Implementing INotifyPropertyChanged or CommunityToolkit ObservableObject
  • Creating or consuming IValueConverter / IMultiValueConverter
  • Choosing the correct BindingMode for a control property
  • Setting BindingContext in XAML or code-behind
  • Using relative bindings (Self, AncestorType, TemplatedParent)
  • Applying StringFormat, FallbackValue, or TargetNullValue
  • Writing AOT-safe code bindings with SetBinding and lambdas (.NET 9+)

When Not to Use

  • CollectionView layouts / templates — use the maui-collectionview skill
  • Shell navigation parameters — use the maui-shell-navigation skill
  • Service registration / DI — use the maui-dependency-injection skill
  • Property-change-triggered animations — use built-in .NET MAUI animation APIs

Inputs

  • A .NET MAUI project targeting .NET 8 or later
  • XAML pages or C# code-behind where bindings are declared
  • A ViewModel class (or plan to create one)

Rules That Change the Answer

Apply these to every binding answer — they are the differences between "it compiles" and "it actually updates the UI".

Situation Do this Not this
Deciding where x:DataType goes Put it wherever a binding scope starts — the page/view root, and each DataTemplate Scattering it on arbitrary children that share the parent's BindingContext
A binding falls back to reflection (XC0022 / XC0023) Add the right x:DataType for that binding scope; for XC0023 remove the explicit x:DataType="{x:Null}" x:DataType="x:Object" to silence it — this disables compile-time checking
A DataTemplate inherits x:DataType from an outer scope (XC0024) Give the DataTemplate its own x:DataType Leaving it to resolve against the wrong type
ViewModel change notification ObservableObject + [ObservableProperty], or implement INotifyPropertyChanged A plain POCO base class — bindings will never update
Bindings show blank Check BindingContext is actually set Assuming the binding path is wrong
Enforcing compiled bindings Set MauiEnableXamlCBindingWithSourceCompilation to true, then <WarningsAsErrors>XC0022;XC0025</WarningsAsErrors> Promoting XC0025 without the switch if the project uses Source= / RelativeSource bindings

Read the full file on GitHub · 422 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 422 lines · 180 tokens per session scan A 7fd85f91cf1e

Subscribe to this mod's changes

maui-data-binding is a skill published in the GitHub repository managedcode/dotnet-skills (477 stars, last pushed 2d ago), licensed MIT. It adds 180 tokens to every session and 3,556 once invoked, about $0.0009 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to maui-data-binding, differing in 0 lines, and is treated as a copy.

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