用Aeson解析复杂的jsons

Question

我正在尝试使用Aeson Library将对API的调用解析为haskell记录类型

我正在使用维基百科页面,并将它们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"},{"ns":0,"title":"Donna Lass"},{"ns":0,"title":"George Lass"},{"ns":0,"title":"Girl"},{"ns":0,"title":"Lassana Diarra"},{"ns":0,"title":"Lightning Lass"},{"ns":0,"title":"Real Madrid"},{"ns":0,"title":"Shadow Lass"},{"ns":0,"title":"Solway Lass"},{"ns":0,"title":"Szymon Lass"},{"ns":0,"title":"The Bonnie Lass o' Fyvie"},{"ns":0,"title":"The Tullaghmurray Lass"},{"ns":0,"title":"Woman"},{"ns":12,"title":"Help:Disambiguation"}]}}}}

我想将它解析为标题和像这样的数据类型的链接列表.

data WikiPage = WikiPage { title :: String,
                           links :: String }

我目前的代码是什么,

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

我收到了错误,

Couldn't match expected type `Data.Text.Internal.Text'
                with actual type `[Char]'
    In the second argument of `(.:)', namely `"title"'

我真的不知道怎么回事,我觉得我在如何映射链接上一定存在问题,但我不确定到底要做什么.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applicative但我不确定如何.)我还没有找到任何像这样分解更复杂的jsons的例子.

Answer 1

我也试图找出一个人.我遇到了同样的问题,我通过{-# LANGUAGE OverloadedStrings #-}在源文件的顶部添加来解决它.我是Haskell的新手,但我相信它为语言增加了一个非官方的扩展,大概是允许字符串加倍,就像其他类似字符串的数据类型一样.