# `Soundcheck.Check.Warning.UnscopedLookupByClientParam`
[🔗](https://github.com/leonqadirie/soundcheck/blob/v0.1.0/lib/soundcheck/check/warning/unscoped_lookup_by_client_param.ex#L1)

## Basics

> #### This check is disabled by default. {: .neutral}
>
> [Learn how to enable it](`e:credo:config_file.html#checks`) via `.credo.exs`.

This check has a base priority of `high` and works with any version of Elixir.

## Explanation

Flags Repo reads in `handle_event/3` and `handle_params/3` that look
a record up by a client-sent param, in a clause that never consults
the current user or scope. Event and URL params come from the client:
any user can send any id.

Before:

    def handle_event("delete", %{"id" => id}, socket) do
      post = Repo.get!(Post, id)
      {:ok, _} = Repo.delete(post)
      {:noreply, socket}
    end

After:

    def handle_event("delete", %{"id" => id}, socket) do
      post = Blog.get_post!(socket.assigns.current_scope, id)
      {:ok, _} = Blog.delete_post(socket.assigns.current_scope, post)
      {:noreply, socket}
    end

A param taints the variables it flows into through `=`, `<-`, and
pipes, within the clause; calls into helpers are not followed. A
clause that reads one of `scope_assigns` (`socket.assigns.current_user`,
or a `%{assigns: %{current_user: user}}` pattern) or calls a function
matching `authorizers` counts as scoped. Modules matching
`excluded_modules` are skipped. Ash calls are not Repo calls: Ash
policies authorize them.

Context functions count as lookups too: a call into one of the
project's own modules whose `Mod.fun` name matches `lookup_functions`
(by default `get_*` and `fetch_*`, such as `Blog.get_post!(id)`).
Calls into dependencies, the standard library, and modules that `use`
an Ash module (domains and resources) never match.

An app that keeps its scope under another assign, such as `:subject`
or `:current_account`, reports every clause until `scope_assigns`
names it:

    {Soundcheck.Check.Warning.UnscopedLookupByClientParam,
     [scope_assigns: [:subject]]}

Confidence: medium. Tier: syntactic (works without compiling).

## Check-Specific Parameters

Use the following parameters to configure this check:

### `:excluded_paths`

  Paths to skip (atoms, binaries as path segments, or regexes).

*This parameter defaults to* `[~r/\/test\//, "test"]`.

### `:strict`

  Unused.

*This parameter defaults to* `false`.

### `:repo_modules`

  Repo modules: atoms or regexes on the alias-expanded name.

*This parameter defaults to* `[~r/\.Repo$/]`.

### `:lookup_functions`

  Context lookups in the project's own modules: `Mod.fun` names, regexes or exact.

*This parameter defaults to* `[~r/\.get_\w+!?$/, ~r/\.fetch_\w+!?$/]`.

### `:scope_assigns`

  Assign keys whose use counts as scoping the clause.

*This parameter defaults to* `[:current_scope, :current_user]`.

### `:authorizers`

  Function names (`fun` or `Mod.fun`, regexes or exact) that authorize.

*This parameter defaults to* `[~r/authoriz/, ~r/permit/, ~r/can\?$/, ~r/allowed\?$/]`.

### `:excluded_modules`

  Modules to skip: atoms or regexes.

*This parameter defaults to* `[~r/Admin/]`.

## General Parameters

Like with all checks, [general params](`e:credo:check_params.html`) can be applied.

Parameters can be configured via the [`.credo.exs` config file](`e:credo:config_file.html`).

---

*Consult [api-reference.md](api-reference.md) for complete listing*