Add optional task to generate style.css.json file before trying to read

CHANGELOG.MD

@@ -1,3 +1,8 @@
+# v0.0.8
+
+## Added
+- `:build_stylesheet_definitions_json_task` config option to run a task for building missing stylesheet definitions JSON file when using `:embed_stylsheet` (/DefactoSoftware/ex_css_modules/pull/#112).
+
 # v0.0.7
 
 ## Added

README.md

@@ -7,7 +7,26 @@
 
 ExCSSModules defines two ways to read the stylesheet: embedded and read.
 
-If you set the `embed_stylesheet` option to the `use` macro the stylesheet definitions JSON have to be compiled before the application is compiled. This flag is used for production to optimize read times.
+If you set the `embed_stylesheet` option to the `use` macro the stylesheet definitions JSON have to be compiled before the application is compiled. This flag is used for production to optimize read times. Additionally, you can add a task to generate missing stylesheet definitions JSON files when compiling ExCSSModules, to prevent compilation errors when one of the stylesheet definitions JSON might be missing:
+
+```ex
+defmodule Mix.Tasks.GenerateMissingJson do
+  use Mix.Task
+
+  @impl Mix.Task
+
+  def run(filename) do
+    with _exit_code = 0 <-
+           Mix.shell().cmd("npx postcss #{filename} --dir ./tmp/postcss --verbose") do
+      {:ok, filename <> ".json"}
+    else
+      _exit_code ->
+        relative_path = Path.relative_to_cwd(filename)
+        exit("Error generating scoped JSON file ./#{relative_path}.json")
+    end
+  end
+end
+```
 
 If you don't set the flag or set it to false, the stylesheet definition JSON files are read live from the server which creates a lot of IO for each request.
 
@@ -16,7 +35,7 @@ Install from [Hex.pm](https://hex.pm/packages/ex_css_modules):
 
 ```ex
 def deps do
-  [{:ex_css_modules, "~> 0.0.7"}]
+  [{:ex_css_modules, "~> 0.0.8"}]
 end
 ```
 

lib/ex_css_modules/ex_css_modules.ex

@@ -31,18 +31,26 @@ defmodule ExCSSModules do
       %{}
 
   """
-  @spec stylesheet(String.t() | map()) :: map()
-  def stylesheet(definition) when is_map(definition), do: definition
-  def stylesheet(definition), do: read_stylesheet(definition)
-
-  defp read_stylesheet(filename) do
-    case File.exists?(filename) do
-      true ->
+  @spec stylesheet(String.t() | map(), module()) :: map()
+  def stylesheet(definition, build_json_task \\ nil)
+  def stylesheet(definition, _build_json_task) when is_map(definition), do: definition
+  def stylesheet(definition, build_json_task), do: read_stylesheet(definition, build_json_task)
+
+  defp read_stylesheet(filename, build_json_task) do
+    cond do
+      File.exists?(filename <> ".json") ->
         (filename <> ".json")
         |> File.read!()
         |> json_library().decode!()
 
-      false ->
+      build_json_task && File.exists?(filename) ->
+        with {:ok, json_filename} <- build_json_task.run(filename: filename) do
+          json_filename
+          |> File.read!()
+          |> json_library().decode!()
+        end
+
+      true ->
         %{}
     end
   end

lib/ex_css_modules/view.ex

@@ -29,19 +29,20 @@ defmodule ExCSSModules.View do
       )
 
     filename = Path.expand(filename, Path.dirname(relative_to))
+    build_json_task = Keyword.get(opts, :build_stylesheet_definitions_json_task, nil)
 
     quote do
       @stylesheet unquote(
                     if embed_stylesheet? do
-                      Macro.escape(ExCSSModules.stylesheet(filename))
+                      Macro.escape(ExCSSModules.stylesheet(filename, build_json_task))
                     else
                       Macro.escape(filename)
                     end
                   )
 
       def stylesheet_definition, do: @stylesheet
 
-      def stylesheet, do: ExCSSModules.stylesheet(@stylesheet)
+      def stylesheet, do: ExCSSModules.stylesheet(@stylesheet, unquote(build_json_task))
 
       def class(key), do: stylesheet() |> ExCSSModules.class(key)
       def class(key, value), do: stylesheet() |> ExCSSModules.class(key, value)

mix.exs

@@ -1,7 +1,7 @@
 defmodule ExCSSModules.Mixfile do
   use Mix.Project
 
-  @version "0.0.7"
+  @version "0.0.8"
 
   def project do
     [