From 996da20aeb217c4f1ba445c1660e3b02aca280ce Mon Sep 17 00:00:00 2001 From: Claudio Ortolina Date: Wed, 6 Aug 2025 09:45:27 +0300 Subject: [PATCH] Sync usage rules --- CLAUDE.md | 290 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 290 insertions(+) diff --git a/CLAUDE.md b/CLAUDE.md index d31872dc..152f9812 100644 --- a/CLAUDE.md +++ b/CLAUDE.md @@ -378,4 +378,294 @@ mix usage_rules.search_docs "Enum.zip" --query-by title - Use `Task.async_stream/3` for concurrent enumeration with back-pressure + +## phoenix:ecto usage +## Ecto Guidelines + +- **Always** preload Ecto associations in queries when they'll be accessed in templates, ie a message that needs to reference the `message.user.email` +- Remember `import Ecto.Query` and other supporting modules when you write `seeds.exs` +- `Ecto.Schema` fields always use the `:string` type, even for `:text`, columns, ie: `field :name, :string` +- `Ecto.Changeset.validate_number/2` **DOES NOT SUPPORT the `:allow_nil` option**. By default, Ecto validations only run if a change for the given field exists and the change value is not nil, so such as option is never needed +- You **must** use `Ecto.Changeset.get_field(changeset, :field)` to access changeset fields +- Fields which are set programatically, such as `user_id`, must not be listed in `cast` calls or similar for security purposes. Instead they must be explicitly set when creating the struct + + + +## phoenix:elixir usage +## Elixir guidelines + +- Elixir lists **do not support index based access via the access syntax** + + **Never do this (invalid)**: + + i = 0 + mylist = ["blue", "green"] + mylist[i] + + Instead, **always** use `Enum.at`, pattern matching, or `List` for index based list access, ie: + + i = 0 + mylist = ["blue", "green"] + Enum.at(mylist, i) + +- Elixir variables are immutable, but can be rebound, so for block expressions like `if`, `case`, `cond`, etc + you *must* bind the result of the expression to a variable if you want to use it and you CANNOT rebind the result inside the expression, ie: + + # INVALID: we are rebinding inside the `if` and the result never gets assigned + if connected?(socket) do + socket = assign(socket, :val, val) + end + + # VALID: we rebind the result of the `if` to a new variable + socket = + if connected?(socket) do + assign(socket, :val, val) + end + +- **Never** nest multiple modules in the same file as it can cause cyclic dependencies and compilation errors +- **Never** use map access syntax (`changeset[:field]`) on structs as they do not implement the Access behaviour by default. For regular structs, you **must** access the fields directly, such as `my_struct.field` or use higher level APIs that are available on the struct if they exist, `Ecto.Changeset.get_field/2` for changesets +- Elixir's standard library has everything necessary for date and time manipulation. Familiarize yourself with the common `Time`, `Date`, `DateTime`, and `Calendar` interfaces by accessing their documentation as necessary. **Never** install additional dependencies unless asked or for date/time parsing (which you can use the `date_time_parser` package) +- Don't use `String.to_atom/1` on user input (memory leak risk) +- Predicate function names should not start with `is_` and should end in a question mark. Names like `is_thing` should be reserved for guards +- Elixir's builtin OTP primitives like `DynamicSupervisor` and `Registry`, require names in the child spec, such as `{DynamicSupervisor, name: MyApp.MyDynamicSup}`, then you can use `DynamicSupervisor.start_child(MyApp.MyDynamicSup, child_spec)` +- Use `Task.async_stream(collection, callback, options)` for concurrent enumeration with back-pressure. The majority of times you will want to pass `timeout: :infinity` as option + +## Mix guidelines + +- Read the docs and options before using tasks (by using `mix help task_name`) +- To debug test failures, run tests in a specific file with `mix test test/my_test.exs` or run all previously failed tests with `mix test --failed` +- `mix deps.clean --all` is **almost never needed**. **Avoid** using it unless you have good reason + + + +## phoenix:html usage +## Phoenix HTML guidelines + +- Phoenix templates **always** use `~H` or .html.heex files (known as HEEx), **never** use `~E` +- **Always** use the imported `Phoenix.Component.form/1` and `Phoenix.Component.inputs_for/1` function to build forms. **Never** use `Phoenix.HTML.form_for` or `Phoenix.HTML.inputs_for` as they are outdated +- When building forms **always** use the already imported `Phoenix.Component.to_form/2` (`assign(socket, form: to_form(...))` and `<.form for={@form} id="msg-form">`), then access those forms in the template via `@form[:field]` +- **Always** add unique DOM IDs to key elements (like forms, buttons, etc) when writing templates, these IDs can later be used in tests (`<.form for={@form} id="product-form">`) +- For "app wide" template imports, you can import/alias into the `my_app_web.ex`'s `html_helpers` block, so they will be available to all LiveViews, LiveComponent's, and all modules that do `use MyAppWeb, :html` (replace "my_app" by the actual app name) + +- Elixir supports `if/else` but **does NOT support `if/else if` or `if/elsif`. **Never use `else if` or `elseif` in Elixir**, **always** use `cond` or `case` for multiple conditionals. + + **Never do this (invalid)**: + + <%= if condition do %> + ... + <% else if other_condition %> + ... + <% end %> + + Instead **always** do this: + + <%= cond do %> + <% condition -> %> + ... + <% condition2 -> %> + ... + <% true -> %> + ... + <% end %> + +- HEEx require special tag annotation if you want to insert literal curly's like `{` or `}`. If you want to show a textual code snippet on the page in a `
` or `` block you *must* annotate the parent tag with `phx-no-curly-interpolation`:
+
+      
+        let obj = {key: "val"}
+      
+
+  Within `phx-no-curly-interpolation` annotated tags, you can use `{` and `}` without escaping them, and dynamic Elixir expressions can still be used with `<%= ... %>` syntax
+
+- HEEx class attrs support lists, but you must **always** use list `[...]` syntax. You can use the class list syntax to conditionally add classes, **always do this for multiple class values**:
+
+      Text
+
+  and **always** wrap `if`'s inside `{...}` expressions with parens, like done above (`if(@other_condition, do: "...", else: "...")`)
+
+  and **never** do this, since it's invalid (note the missing `[` and `]`):
+
+       ...
+      => Raises compile syntax error on invalid HEEx attr syntax
+
+- **Never** use `<% Enum.each %>` or non-for comprehensions for generating template content, instead **always** use `<%= for item <- @collection do %>`
+- HEEx HTML comments use `<%!-- comment --%>`. **Always** use the HEEx HTML comment syntax for template comments (`<%!-- comment --%>`)
+- HEEx allows interpolation via `{...}` and `<%= ... %>`, but the `<%= %>` **only** works within tag bodies. **Always** use the `{...}` syntax for interpolation within tag attributes, and for interpolation of values within tag bodies. **Always** interpolate block constructs (if, cond, case, for) within tag bodies using `<%= ... %>`.
+
+  **Always** do this:
+
+      

+        {@my_assign}
+        <%= if @some_block_condition do %>
+          {@another_assign}
+        <% end %>
+      

+
+  and **Never** do this – the program will terminate with a syntax error:
+
+      <%!-- THIS IS INVALID NEVER EVER DO THIS --%>
+      

+        {if @invalid_block_construct do}
+        {end}
+      

+
+
+
+## phoenix:liveview usage
+## Phoenix LiveView guidelines
+
+- **Never** use the deprecated `live_redirect` and `live_patch` functions, instead **always** use the `<.link navigate={href}>` and  `<.link patch={href}>` in templates, and `push_navigate` and `push_patch` functions LiveViews
+- **Avoid LiveComponent's** unless you have a strong, specific need for them
+- LiveViews should be named like `AppWeb.WeatherLive`, with a `Live` suffix. When you go to add LiveView routes to the router, the default `:browser` scope is **already aliased** with the `AppWeb` module, so you can just do `live "/weather", WeatherLive`
+- Remember anytime you use `phx-hook="MyHook"` and that js hook manages its own DOM, you **must** also set the `phx-update="ignore"` attribute
+- **Never** write embedded `