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Mention dbg/2 can be plugged into a pipeline #1296

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josevalim merged 3 commits into from
Jan 9, 2026
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Mention dbg/2 can be plugged into a pipeline #1296

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c374274
Mention `dbg/2` can be plugged into a pipeline
Gladear Jan 7, 2026
3d97cec
Move the mention to `Plug.Builder`
Gladear Jan 9, 2026
e503a65
feedback: Mention _why_ it works
Gladear Jan 9, 2026
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17 changes: 17 additions & 0 deletions lib/plug/builder.ex
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Expand Up @@ -123,6 +123,23 @@ defmodule Plug.Builder do
halt(conn)
end
end

## Debugging a pipeline

During development, you may wish to display the current state of the connection
at a certain point in the pipeline. This can be achieved by plugging the `dbg/2`
macro from Elixir. Since it accepts and returns the connection as first argument,
and takes options as the second, it just works:

defmodule PlugWithDbg do
use Plug.Builder

plug Plug.RewriteOn
plug :dbg
plug Plug.MethodOverride
plug :dbg, charlists: :as_lists
end

"""

@type plug :: module | atom
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