如何将Azure Function路由的最后两个参数设置为可选？

要将moneyCurrency和moneyAmount设为可选参数，需遵循Azure Function的路由规则，同时配合参数默认值或可空类型实现，具体步骤如下：

正确实现方案 #

1. 调整路由模板 #

将最后两个参数标记为可选，注意可选参数必须放在路由的最末尾，修改后的路由格式如下：

Route = "createmoney/printdate/{printDate}/moneycurrency/{moneyCurrency?}/moneyamount/{moneyAmount?}"

2. 配置方法参数 #

根据需求选择以下两种方式之一：

• 设置默认值：当请求未传入参数时，使用预设的默认值

  [FunctionName("MakeMeRich")]
  public async Task<IActionResult> MakeMeRich(
      [HttpTrigger(AuthorizationLevel.Function, "get", Route = "createmoney/printdate/{printDate}/moneycurrency/{moneyCurrency?}/moneyamount/{moneyAmount?}")] HttpRequest req,
      ILogger log, 
      string printDate, 
      string moneyCurrency = "USD",  // 默认货币为USD
      decimal moneyAmount = 0)       // 默认金额为0
  {
      // 函数业务逻辑
      return new OkObjectResult($"打印日期: {printDate}, 货币: {moneyCurrency}, 金额: {moneyAmount}");
  }
  

• 使用可空类型：允许参数为null，需自行处理空值场景

  [FunctionName("MakeMeRich")]
  public async Task<IActionResult> MakeMeRich(
      [HttpTrigger(AuthorizationLevel.Function, "get", Route = "createmoney/printdate/{printDate}/moneycurrency/{moneyCurrency?}/moneyamount/{moneyAmount?}")] HttpRequest req,
      ILogger log, 
      string printDate, 
      string? moneyCurrency,  // 可空字符串
      decimal? moneyAmount)   // 可空decimal
  {
      // 处理null值逻辑，比如赋默认值
      var currency = moneyCurrency ?? "CNY";
      var amount = moneyAmount ?? 100;
      return new OkObjectResult($"打印日期: {printDate}, 货币: {currency}, 金额: {amount}");
  }
  

关键注意事项 #

• 可选参数必须位于路由的最后段，不能在中间插入可选参数，否则路由匹配会失败
• 路由中的{参数名?}标记和方法参数的默认值/可空类型必须配套使用，缺一不可

合法请求示例 #

• 传入所有参数：GET /api/createmoney/printdate/2024-05-20/moneycurrency/EUR/moneyamount/1000
• 仅传打印日期和货币：GET /api/createmoney/printdate/2024-05-20/moneycurrency/GBP
• 仅传打印日期：GET /api/createmoney/printdate/2024-05-20

内容的提问来源于stack exchange，提问作者MidTown