我试图使用Aeson库解析一个API到一个
haskell记录类型的调用
我使用维基百科页面,并将其解析为标题和链接列表.
一个样本就是这个,
{"query":{"pages":{"6278041":{"pageid":6278041,"ns":0,"title":"Lass","links":[{"ns":0,"title":"Acronym"},{"ns":0,"title":"Dead Like Me"},"title":"Donna Lass"},"title":"George Lass"},"title":"Girl"},"title":"Lassana Diarra"},"title":"Lightning Lass"},"title":"Real Madrid"},"title":"Shadow Lass"},"title":"Solway Lass"},"title":"Szymon Lass"},"title":"The Bonnie Lass o' Fyvie"},"title":"The Tullaghmurray Lass"},"title":"Woman"},{"ns":12,"title":"Help:Disambiguation"}]}}}}
data WikiPage = WikiPage { title :: String,links :: String }
我目前拥有的是什么代码,
instance FromJSON WikiPage where
parseJSON j = do
o <- parseJSON j
let id = head $o .: "query" .: "pages"
let name = o .: "query" .: "pages" .: id .: "title"
let links = mapM (.: "title") (o .: "query".: "pages" .: id .: "links")
return $WikiPage name links
我收到错误,
Couldn't match expected type `Data.Text.Internal.Text'
with actual type `[Char]'
In the second argument of `(.:)',namely `"title"'
我真的不知道发生了什么,我觉得我如何映射链接一定是一个问题,但我不确定要做什么.我也不知道我应该如何在第二个查询字符串中使用id,因为它是一个解析器(我确定我需要在这里使用应用程序,但我不知道如何).我还没有找到任何分解更复杂的jsons这样的例子.
