c# - 如何让可选的路由参数允许为空？

Question

我试图在我的一个 Controller 方法中允许空值。它看起来像这样:

[Route("items/type/{catalogTypeId}/brand/{catalogBrandId}")]
public async Task<IActionResult> Items(int? catalogTypeId, int? catalogBrandId, [FromQuery] int pageSize = 6, [FromQuery] int pageIndex = 0)

当我尝试邮寄 items/type/1/brand/null?pageSize=6&pageIndex=0 时，它给我一个错误 400

"The value 'null' is not valid".

我将如何允许空值？

Answer 1

使路由模板参数可选 {catalogBrandId?}

[Route("items/type/{catalogTypeId}/brand/{catalogBrandId?}")]
public async Task<IActionResult> Items(int? catalogTypeId, int? catalogBrandId = null, [FromQuery] int pageSize = 6, [FromQuery] int pageIndex = 0)

并将其从 URL 中排除

items/type/1/brand?pageSize=6&pageIndex=0

您实际上应该使用多个路由来获得更清晰的 URL

[Route("items")]
[Route("items/type/{catalogTypeId}")]
[Route("items/type/{catalogTypeId}/brand/{catalogBrandId}")]
public async Task<IActionResult> Items(int? catalogTypeId = null, int? catalogBrandId = null, [FromQuery] int pageSize = 6, [FromQuery] int pageIndex = 0)

请注意，模板不再是可选的，但操作中的参数是可选的。

这将允许

items?pageSize=6&pageIndex=0
items/type/1?pageSize=6&pageIndex=0
items/type/1/brand/2?pageSize=6&pageIndex=0