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POparsing complicated jsons with Aeson
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copied!<p>I'm trying to parse a call to an API into a haskell record type using the Aeson Library</p> <p>I'm using wikipedia pages, and parsing them to the title and a list of links. A sample would be this,</p> <pre><code>{"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"}]}}}} </code></pre> <p>and I would like to parse it to the title and a list of links in a data type like this.</p> <pre><code>data WikiPage = WikiPage { title :: String, links :: String } </code></pre> <p>What code I currently have is this,</p> <pre><code>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 </code></pre> <p>I'm getting the error, </p> <pre><code>Couldn't match expected type `Data.Text.Internal.Text' with actual type `[Char]' In the second argument of `(.:)', namely `"title"' </code></pre> <p>I don't really get whats going on, I feel like there must be a problem with how I'm mapping over the links but I'm not sure exactly what has to be done. I also don't get how I'm supposed to use id in the second query string as it's a parser (I'm sure I need to use applicative in here somewhere but I'm not sure how.) I haven't found any examples that decompose more complicated jsons like this.</p>

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