@spec class_names(list()) :: String.t()

Merges CSS classes, filtering out nil and empty values.

Supports multiple input formats for flexible class composition:

• Strings: "btn btn-primary"
• Lists: ["btn", "btn-primary"]
• Conditional tuples: {"btn-disabled", false} (included only if true)
• Nested lists: ["btn", ["btn-primary", "btn-lg"]]
• Mixed: ["btn", {"btn-disabled", @disabled}, @extra_class]

Examples

iex> MithrilUI.Helpers.class_names(["btn", "btn-primary", nil, ""])
"btn btn-primary"

iex> MithrilUI.Helpers.class_names(["btn", {"btn-primary", true}, {"btn-disabled", false}])
"btn btn-primary"

iex> MithrilUI.Helpers.class_names(["base", ["nested", "classes"]])
"base nested classes"

Usage in Components

All MithrilUI components accept the :class attribute as either a string or list, enabling flexible conditional class composition:

# Simple string
<.button class="my-custom-class">Click</.button>

# List with conditionals
<.button class={[
  "w-12 h-12 p-0 rounded-lg",
  if(@selected, do: "ring-2 ring-white", else: "opacity-60")
]}>
  Click
</.button>

# Using conditional tuples
<.card class={[
  "custom-card",
  {"shadow-xl", @elevated},
  {"border-primary", @highlighted}
]}>
  Content
</.card>

@spec field_errors(Phoenix.HTML.FormField.t() | nil) :: [String.t()]

Extracts the errors list from a form field.

Returns an empty list if the field has no errors or if the form has not been validated yet.

Examples

iex> MithrilUI.Helpers.field_errors(%Phoenix.HTML.FormField{errors: [{"is required", []}]})
["is required"]

@spec has_errors?(Phoenix.HTML.FormField.t() | nil) :: boolean()

Checks if a form field has any errors.

Examples

iex> MithrilUI.Helpers.has_errors?(%Phoenix.HTML.FormField{errors: [{"is required", []}]})
true

iex> MithrilUI.Helpers.has_errors?(%Phoenix.HTML.FormField{errors: []})
false

@spec normalize_class_attr(String.t() | list() | nil) :: String.t() | list() | nil

Normalizes a class value that may be a string, list, or nil.

This is useful when you need to programmatically work with class values that could be in different formats.

Examples

iex> MithrilUI.Helpers.normalize_class_attr(nil)
nil

iex> MithrilUI.Helpers.normalize_class_attr("btn btn-primary")
"btn btn-primary"

iex> MithrilUI.Helpers.normalize_class_attr(["btn", "btn-primary"])
["btn", "btn-primary"]

iex> MithrilUI.Helpers.normalize_class_attr(["btn", nil, {"active", true}])
["btn", nil, {"active", true}]

@spec translate_error({String.t(), keyword()}) :: String.t()

Translates form field errors using the configured translator.

By default, uses simple string interpolation. Applications can configure a custom translator function:

config :mithril_ui,
  error_translator: {MyAppWeb.CoreComponents, :translate_error}

Examples

iex> MithrilUI.Helpers.translate_error({"is required", []})
"is required"

iex> MithrilUI.Helpers.translate_error({"must be at least %{count} characters", [count: 8]})
"must be at least 8 characters"

@spec unique_id(String.t()) :: String.t()

Generates a unique ID for DOM elements.

Examples

iex> MithrilUI.Helpers.unique_id("modal")
"modal-abc123def"