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模型上的验证辅助工具

直接在共享代码中添加可复用的验证逻辑

模型上的验证辅助工具 是 CoddyKit 上的免费 Kotlin Multiplatform Academy 课时。这是第 4 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Kotlin Multiplatform Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Kotlin Multiplatform Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Models Can Check Themselves

A model should know what valid looks like. Adding validation to shared code means both apps enforce the same rules.

A Computed Property

A computed property derives a value from the model's fields. It runs whenever you read it, with no stored state.

data class User(val name: String) {
  val isNamed: Boolean get() = name.isNotBlank()
}

Expose an isValid Flag

Give the model an isValid property that bundles all its rules into one boolean both apps can trust.

val isValid: Boolean
  get() = name.length in 2..30

Add a Validation Method

A function on the model can run a check and return a result, keeping the logic right next to the data.

fun hasValidEmail(): Boolean =
  email.contains("@")

Return Specific Errors

Instead of a plain boolean, return a list of messages so the UI can tell the user exactly what to fix.

fun errors(): List<String> =
  if (name.isBlank()) listOf("Name required") else emptyList()

Reuse Across Fields

Extract a small helper so several models can share the same rule, like a reusable email or length check.

fun String.isEmail(): Boolean = contains("@") && contains(".")

Validate in commonMain

Keep every rule in commonMain so Android and iOS validate identically and your forms never disagree.

Guard at Creation with init

An init block with require can reject bad data the moment a model is built, stopping invalid objects early.

init { require(name.isNotBlank()) { "Name required" } }

Keep Validation Pure

Validation should only read fields and return results, never touch UI or network. Pure rules stay portable and testable.

Easy to Unit Test

Because the logic is plain Kotlin, you can test it once in commonTest and trust it on every platform.

Why This Matters

Shared validation means a rule changes in exactly one place and instantly applies to both apps. 🙂

Quick Check

Where should reusable model validation live?

Recap

Add validation as computed properties, methods or init checks in commonMain, keep it pure, and both apps enforce identical rules.

常见问题解答

「模型上的验证辅助工具」课时是免费的吗？

是的 — 「模型上的验证辅助工具」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Kotlin Multiplatform Academy 课程的其余内容，请升级到 CoddyKit PRO。 Kotlin Multiplatform Academy 课程共包含 4 节课。

「模型上的验证辅助工具」这节课中我会学到什么？

直接在共享代码中添加可复用的验证逻辑你通过在浏览器中直接运行的动手代码来练习 Kotlin Multiplatform Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Kotlin Multiplatform Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Kotlin Multiplatform Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 4 节课，共 4 节。

「模型上的验证辅助工具」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Kotlin Multiplatform Academy 课中编写并运行代码吗？

能。每节 Kotlin Multiplatform Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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