| -api-id | -api-type |
|---|---|
M:Windows.Foundation.WwwFormUrlDecoder.GetFirstValueByName(System.String) |
winrt method |
Gets the first name-value pair that has the specified name, as obtained from the constructing Uniform Resource Identifier (URI) query string.
The name of the value to get.
The first value in list order that corresponds with name.
This method throws an exception (an error for JavaScript) if the value specified as name doesn't exist in the WwwFormUrlDecoder collection. For .NET code, this is typed as System.ArgumentException. You'll probably want to call GetFirstValueByName within a try-catch block so you have a chance to handle the exception.
What to do with duplicate names in a query string from a GET request is not specified by any Internet standard. A common practice is to process the first value and ignore the subsequent duplicates. The GetFirstValueByName method provides that behavior. It also provides the de-facto "index by string" behavior, which is typically what you want when you're processing a query string. Your app is expecting certain names to be present on the query string, and wants to retrieve the associated value.