如何转换XmlProvider自动提供的选项类型<>;。域类型输入到F#中的枚举中?
假设我有以下XML:如何转换XmlProvider自动提供的选项类型<>;。域类型输入到F#中的枚举中?,xml,f#,enumeration,type-providers,f#-data,Xml,F#,Enumeration,Type Providers,F# Data,假设我有以下XML: <?xml version="1.0" encoding="UTF-16"?> <iAmConfused> <helpMe feeling="anger" strength="100" mapping="1-1" /> <helpMe feeling="frustration" strength="15" mapping="1-n" /> <helpMe feeling="helplessness
<?xml version="1.0" encoding="UTF-16"?>
<iAmConfused>
<helpMe feeling="anger" strength="100" mapping="1-1" />
<helpMe feeling="frustration" strength="15" mapping="1-n" />
<helpMe feeling="helplessness" strength="365" mapping="1-1" />
<helpMe feeling="despair" strength="-1" mapping="1-n" />
</iAmConfused>
然后将?
替换为
string e.Strength
string (defaultArg e.Mapping "")
为我提供“一些(1-1)”
或“一些(1-n)”
以获得帮助。映射
不是我想要的。如果我试图将
?
替换为
string e.Strength
string (defaultArg e.Mapping "")
然后,FSI理所当然地抱怨:
test.fs(165,38): error FS0001: This expression was expected to have type
'a option
but here has type
XmlProvider<...>.DomainTypes.MappingChoice
test.fs(165,38):错误FS0001:此表达式应具有类型
"选择",
但这里有一种类型
XmlProvider.DomainTypes.MappingChoice
要将字符串转换为映射类型
,您可以定义一个小辅助函数:
let convert m =
match m with
| "1-1" -> mappingType.oneToOneMapping
| _ -> mappingType.oneToManyMapping
这将使您能够编写投影,如:
let iWantThisMap =
iAmConfusedXml.GetHelpMes()
|> Seq.map (fun e -> e.Feeling, {
strength = e.Strength;
mapping = (e.Mapping.Value |> convert) })
|> Map.ofSeq
现在,这里有点作弊,因为它只是调用e.Mapping.Value
。如果e.Mapping
为None
,则可能会引发异常,但如果此处提供了数据,则会发生异常,因为e.Mapping
始终具有值