I'm trying to learn IHP by following the guide. And what I've noticed, that there aren't any functions and other stuff to deal with dates.

For example:

I wanted to change a date of a post to 'NOW()' when updating it

    action UpdatePostAction { postId } = do
        post <- fetch postId
        post
            |> buildPost
            |> validateIsUnique #title
            >>= ifValid \case
                Left post -> render EditView { .. }
                Right post -> do
                    post <- post
                        |> set #created_at '...' --  change '...' to something :)
                        |> updateRecord
                    let t = get #title post
                    setSuccessMessage $ "Post \'" <> t <> "\' updated"
                    redirectTo PostsAction

So that is the question: What i can do with this 'set-statement' to actually change the date ? Or is there any 'already-specified' functions to do it ?

CodePudding user response：

To handle dates and times in IHP we use the time package. To get the current time, there's a simple function from Data.Time.Clock named getCurrentTime :: IO UTCTime.

Right post -> do
  currentTime <- getCurrentTime
  post <- post
    |> set #createdAt currentTime
    |> updateRecord
   ... ​

William Yao has an excellent cheatsheet to the time package which I would highly recommend if you wish to dive deeper into the topic. I pretty much always have a tab to this open!

Also, in calls to set make sure you use camelCase, IHP converts this into the snake_case database columns for you :)