vb.net 中的 web 方法：可选参数 - 太多重载
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web method in vb.net: optional parameters - too many for overloading
提问by user2366211
Old subject but with a twist - I searched and couldn't find answer to that.
旧主题但有一个转折 - 我搜索并找不到答案。
I know I can't use optional parameters with default values with web method so I have to use function overloading but...I saw examples of one optional parameter and I have around 10!
我知道我不能在 web 方法中使用带有默认值的可选参数，所以我必须使用函数重载但是......我看到了一个可选参数的示例，我有大约 10 个！
If I understand well for 3 optional parameters I will need 7 overloaded functions (3 for 1 parameter, 3 for 2 and 1 for the whole 3) so for how many I need for 10? a lot! there must be a better way, no? and please don't tell me to use WCF - I can't switch to that now and I have to use WSDL
如果我对 3 个可选参数理解得很好，我将需要 7 个重载函数（1 个参数为 3 个，2 个为 3 个，整个 3 个为 1 个），那么 10 个需要多少个？很多！一定有更好的方法，不是吗？请不要告诉我使用 WCF - 我现在无法切换到，我必须使用 WSDL
thanks a lot for helping
非常感谢您的帮助
回答by Matt Wilko
Instead of using many optional parameters you could just pass an Object (Class) that has properties with a default value. That way it can work the same as optional parameters:
您可以只传递具有默认值属性的对象（类），而不是使用许多可选参数。这样它就可以像可选参数一样工作：
Public Class Parameters
Public Property Name As String = "Undefined"
Public Property Country as string = "United Kingdom"
End Class
Define your WebMethod to accept this object type
定义您的 WebMethod 以接受此对象类型
Public Function WebMethod(prm as Parameters)
Usage:
用法：
Pass parameters with a Name:
使用名称传递参数：
WebMethod(New Parameters With {.Name = "Jane"})
Pass Parameters with a Name and Country:
传递带有名称和国家/地区的参数：
WebMethod(New Parameters With {.Name = "Amr", .Country = "Egypt"})
Pass Parameters with just Country:
仅使用 Country 传递参数：
WebMethod(New Parameters With {.Country = "China"})
回答by George
You can declare variables as Nullable (of <your type>)and just have one webservice with all 10 parameters
您可以将变量声明为，Nullable (of <your type>)并且只有一个包含所有 10 个参数的网络服务
This is your Webmethod with only 2 optional parameters, but you can easily expand on this to 10:
这是只有 2 个可选参数的 Webmethod，但您可以轻松地将其扩展到 10 个：
<WebMethod(Description:="TEST1")> _
Public Function TEST1(<XmlElement()> param1 As Nullable(Of Double), <XmlElement()> param2 As Nullable(Of Double)) As <XmlElement()> Double
Try
Dim result As Double = 0
If Not param1 Is Nothing Then
result += param1
End If
If Not param2 Is Nothing Then
result += param2
End If
Return result
Catch ex As Exception
End Try
Return 0
End Function
This SoapUI call:
这个 SoapUI 调用：
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:not="http://mysite.org/">
<soapenv:Header/>
<soapenv:Body>
<not:TEST1>
<not:param1>1</not:param1>
<not:param2>2</not:param2>
</not:TEST1>
</soapenv:Body>
</soapenv:Envelope>
Results in this:
结果如下：
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<soap:Body>
<TEST1Response xmlns="http://mysite.org/">
<TEST1Result>3</TEST1Result>
</TEST1Response>
</soap:Body>
</soap:Envelope>
This SoapUI call:
这个 SoapUI 调用：
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:not="http://mysite.org/">
<soapenv:Header/>
<soapenv:Body>
<not:TEST1>
<not:param1>1</not:param1>
</not:TEST1>
</soapenv:Body>
</soapenv:Envelope>
Results in this:
结果如下：
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<soap:Body>
<TEST1Response xmlns="http://mysite.org/">
<TEST1Result>1</TEST1Result>
</TEST1Response>
</soap:Body>
</soap:Envelope>
Nullable (of Double)in this example both parameters are optional.
Nullable (of Double)在这个例子中，两个参数都是可选的。
