Lotus.Middleware (Lotus v0.16.5)

Generic middleware pipeline for query execution and schema discovery hooks.

Each middleware module implements init/1 and call/2, following the standard Plug pattern:

defmodule MyApp.AuditPlug do
  def init(opts), do: opts

  def call(payload, opts) do
    {:cont, payload}   # continue to next middleware
    # or
    {:halt, "reason"}  # stop pipeline, Lotus returns {:error, reason}
  end
end

Pipeline Events

Event	Triggered
`:before_query`	After preflight visibility check, before SQL execution
`:after_query`	After execution, before result returned to caller
`:after_list_schemas`	After schema discovery and visibility filtering
`:after_list_tables`	After table discovery and visibility filtering
`:after_get_table_schema`	After table schema introspection and column visibility
`:after_list_relations`	After relation discovery and visibility filtering

Configuration

config :lotus,
  middleware: %{
    before_query: [
      {MyApp.AccessControlPlug, []},
      {MyApp.QueryAuditPlug, [repo: MyApp.AuditRepo]}
    ],
    after_query: [
      {MyApp.QueryAuditPlug, [repo: MyApp.AuditRepo]}
    ],
    after_list_tables: [
      {MyApp.TableFilterPlug, []}
    ]
  }

Context

A :context key carries opaque user data (e.g. the current user) through to middleware. Lotus never inspects this value.

Summary

Types

compiled_entry()

event()

middleware_spec()

pipeline_result()

Functions

compile(middleware_config)

Compiles all middleware by calling init/1 on each module and stores the result in :persistent_term for fast runtime access.

run(event, payload)

Runs the middleware pipeline for the given event.