做一个参数可选的一个C＃的WebMethod的最佳方式

问题描述：

什么是支持传递给一个C＃函数的可选数据的最佳方式？

What is the best way of supporting optional data passed to a C# function?

我在.net定义5个参数的Web服务功能：

I have web service function in .Net which defines 5 arguments:

[WebMethod]
    public string UploadFile( string wsURL
        , byte[] incomingArray
        , string FileName
        , string RecordTypeName
        , MetaData[] metaDataArray)

这个函数的code不是太长（但不是小事其一），并且只有一个在那里我执行此测试功能的地方，如果有任何元数据[]进行处理：

The code of this function is not too long (but not trivial either) and there is only one place in the the function where I perform this test if there is any MetaData[] to be processed:

        if (metaDataArray.Length > 0)
        {
            Update update = BuildMetaData(metaDataArray);
            treq2.Items = new Operation[] { sru, cin, update, fetch};
        }
        else
        {
            treq2.Items = new Operation[] { sru, cin, fetch};
        }

我需要一个快速和肮脏的版本上面只需要4个参数（即无元数据数组作为最后一个参数），所以我克隆整体功能并删除了IF-ELSE块指的元数据。丑陋的我知道。

I needed a quick and dirty version of the above which only takes 4 arguments (i.e. no "Metadata" array as a final argument) so I cloned the whole function and removed the IF-ELSE block refering to metadata. Ugly I know.

[WebMethod]
    public string UploadFileBasic( string wsURL
        , byte[] incomingArray
        , string FileName
        , string RecordTypeName)

现在我想更好地做的事情，我期待的意见的最佳方式来支持这一点。我不想负担与创建一个空数组作为第五个参数客户端程序......我想有我的web服务功能，以足够的智慧来处理这个可选数据。谢谢。

Now I want to do things better and I am looking for advice on the best way to support this. I do not want to burden the client program with creating an empty array as a 5th parameter...I want to have my web service functions to be smart enough to handle this optional data. Thanks.

答

更改支票在需要5参数（注意，你应该检查，如果该值为null反正）的方法。

Change your check in the method that takes 5 arguments to (note, that you should be checking if the value is null anyway).

    if (metaDataArray != null && metaDataArray.Length > 0)
    {
        Update update = BuildMetaData(metaDataArray);
        treq2.Items = new Operation[] { sru, cin, update, fetch };
    }
    else
    {
        treq2.Items = new Operation[] { sru, cin, fetch};
    }

然后，只需你有4参数版本内部调用5参数版本与metaDataArray参数为null。

Then, simply have your 4 argument version call the 5 argument version internally with the metaDataArray argument null.

[WebMethod]
public string UploadFileBasic( string wsURL,
                               byte[] incomingArray,
                               string FileName,
                               string RecordTypeName)
{
    return UploadFile( wsUrl, incomingArray, fileName, RecordTypeName, null );
}

做一个参数可选的一个C＃的WebMethod的最佳方式

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