蒸气 Swift 错误 "Reference to member 'sqlite' cannot be resolved without a contextual type"

Question

在全新安装 Vapor（来自 homebrew）时，我调用：

vapor new Bridge -> 成功
vapor xcode -> 成功
y（询问我是否要打开 Xcode 中的项目）-> 打开 Xcode 项目
vapor --version -> 3.1.10
vapor build -> 失败

我得到的错误是：

[1/3] Compiling App configure.swift
/Users/josh/Applications/Xcode/Projects/Bridge/Sources/App/configure.swift:31:49: error: reference to member 'sqlite' cannot be resolved without a contextual type
    migrations.add(model: Todo.self, database: .sqlite)
                                               ~^~~~~~
[2/3] Compiling App app.swift

版本号：

macOS：10.15.3 (19D76)
Xcode: 11.4 (11E146)
蒸气：3.1.10
Swift: 5.2

如果您能提供解决此错误的帮助，我们将不胜感激！如果我可以提供更多信息，请告诉我。谢谢！

Answer 1

是的，Vapor 3 在 Swift 5.2
上遇到编译问题 https://forums.swift.org/t/vapor-3-swift-5-2-regression/34764

migrations.add(model: Todo.self, database: .sqlite)

以上代码在 Swift 5.1 中编译良好，现在将导致以下错误：

Reference to member 'sqlite' cannot be resolved without a contextual type

这可以通过使用显式类型而不是前导点语法来解决：

migrations.add(model: Todo.self, database: DatabaseIdentifier<SQLiteDatabase>.sqlite)

Answer 2

在ToDoclass中添加typelias，当你使用Swift5.2

final class Todo: SQLiteModel {

    typealias Database = SQLiteDatabase

    ....
}

蒸气 Swift 错误 "Reference to member 'sqlite' cannot be resolved without a contextual type"

Vapor Swift Error "Reference to member 'sqlite' cannot be resolved without a contextual type"

swift

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