Preview for filter by category LUA filter alternative + add category-filter extension to repo

site/.quartoignore

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+**/*.Rmd

site/_extensions/category-filter/_extension.yml

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+title: Category Filter
+author: Nik Richers
+version: 1.0.0
+contributes:
+  filters:
+    - category-filter.lua

site/_extensions/category-filter/category-filter.lua

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+-- Category Filter Lua Extension
+-- Reads listing-filter from YAML frontmatter and injects config as a data attribute
+
+local function meta_to_native(val)
+  if val == nil then
+    return nil
+  end
+
+  local mt = getmetatable(val)
+
+  -- Check for pandoc List type (used for YAML arrays)
+  if mt and mt.__name == "List" then
+    local arr = {}
+    for i, item in ipairs(val) do
+      arr[i] = meta_to_native(item)
+    end
+    return arr
+  end
+
+  -- Check for pandoc Inlines (YAML string values become Inlines)
+  if mt and (mt.__name == "Inlines" or mt.__name == "Blocks") then
+    return pandoc.utils.stringify(val)
+  end
+
+  -- Plain Lua types
+  local t = type(val)
+  if t == "string" or t == "number" or t == "boolean" then
+    return val
+  elseif t == "table" then
+    -- Check if it's an array-like table
+    if #val > 0 and val[1] ~= nil then
+      local arr = {}
+      for i, item in ipairs(val) do
+        arr[i] = meta_to_native(item)
+      end
+      return arr
+    else
+      -- It's a map/object
+      local obj = {}
+      for k, v in pairs(val) do
+        obj[k] = meta_to_native(v)
+      end
+      return obj
+    end
+  end
+
+  -- Fallback: try stringify
+  return pandoc.utils.stringify(val)
+end
+
+function Meta(meta)
+  if meta['listing-filter'] then
+    local config = meta_to_native(meta['listing-filter'])
+    local json = quarto.json.encode(config)
+    local escaped = json:gsub("'", "'")
+    quarto.doc.include_text("after-body",
+      '<div id="listing-filter-config" style="display:none" data-config=\'' .. escaped .. '\'></div>')
+  end
+end