yesod

Say, in Yesod/Persistent, I have models setup like so: User ident Text password Text Maybe UniqueUser ident Question title Text asker UserId Eq And I have a list of Question s, and would like to retrieve the corresponding list of User s. How would I go about doing this? I've thought about joins, but those are one-to-many, not one-to-one (I suppose it doesn't matter, but I'd like a simpler solution). Manually doing the join is also an option, but I'm worried about performance - I have questions <- runDB $ selectList [QuestionTitle !=. ""] [LimitTo 10] let askerIds = map (\(Entity _ q) ->

This question already has an answer here: What's wrong with this YesodAuth instance? 1 answer I'm trying to add instance YesodAuthEmail App to the Yesod-Postgres scaffolding (yesod version 1.6) and getting stuck on a compile error. The relevant code is: instance YesodAuth App where type AuthId App = UserId .... authPlugins :: App -> [AuthPlugin App] authPlugins app = [authOpenId Claimed []] ++ extraAuthPlugins where extraAuthPlugins = [ authEmail ] instance YesodAuthEmail App where type AuthEmailId App = UserId afterPasswordRoute _ = HomeR addUnverified email verkey = runDB $ insert $ User

I am using Yesod on my first site and I have a list of news items: NewsItem date UTCTime default=CURRENT_TIME title String content String author String which are retrieved in my handler: newsitems <- runDB $ selectList [] [Desc NewsItemDate] and ultimately used in my template: $if null newsitems <p>No news. $else $forall Entity id entry <- newsitems <article> <h4>#{newsItemDate entry} <p>#{newsItemContent entry} But I get an error about datatypes: Handler/Home.hs:20:11: No instance for (Text.Blaze.ToMarkup time-1.4:Data.Time.Clock.UTC.UTCTime) arising from a use of `toHtml' Possible fix: add

Context: I'm approaching Haskell from a standpoint of converting runtime errors to compile-time errors. My hypothesis is that this is possible if one can codify business logic within the program's types itself. I'm writing a Telegram bot, which should be accessible by users within my company. To achieve this "restriction", whenever someone starts chatting with the bot it will look up the chat_id in a table and check if a valid oauth_token exists. If not, the user will first be sent a link to complete a Google OAuth (our company's email is hosted on Google Apps for Business). share [mkPersist

How can I compose Database.Esqueleto queries in a modular way such that after defining a "base" query and the corresponding result set, I can restrict the result set by adding additional inner joins and where expressions. Also, how can I convert the base query that returns a list of entities (or field tuples) into a query that counts the result set since the base query is not executed as such, but a modified version of it with LIMIT and OFFSET. The following incorrect Haskell code snippet adopted from the Yesod Book hopefully clarifies what I'm aiming at. {-# LANGUAGE QuasiQuotes,