How to work with dates in IHP ? Is there any 'default' ways?

Question

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 ?

score 2 · Accepted Answer · answered Sep 08 '21 at 23:43

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 :)

How to work with dates in IHP ? Is there any 'default' ways?

1 Answers1