Hakyll.Web.Page.Metadata
Description
Provides various functions to manipulate the metadata fields of a page
- getField :: String -> Page a -> String
- getFieldMaybe :: String -> Page a -> Maybe String
- setField :: String -> String -> Page a -> Page a
- setFieldA :: Arrow a => String -> a x String -> a (Page b, x) (Page b)
- renderField :: String -> String -> (String -> String) -> Page a -> Page a
- changeField :: String -> (String -> String) -> Page a -> Page a
- copyField :: String -> String -> Page a -> Page a
- renderDateField :: String -> String -> String -> Page a -> Page a
- renderDateFieldWith :: TimeLocale -> String -> String -> String -> Page a -> Page a
Documentation
Get a metadata field. If the field does not exist, the empty string is returned.
Get a field in a Maybe wrapper
Add a metadata field. If the field already exists, it is not overwritten.
Arrow-based variant of setField. Because of it's type, this function is
very usable together with the different require functions.
Arguments
| :: String | Key of which the value should be copied |
| -> String | Key the value should be copied to |
| -> (String -> String) | Function to apply on the value |
| -> Page a | Page on which this should be applied |
| -> Page a | Resulting page |
Do something with a metadata value, but keep the old value as well. If the
key given is not present in the metadata, nothing will happen. If the source
and destination keys are the same, the value will be changed (but you should
use changeField for this purpose).
Arguments
| :: String | Key to change. |
| -> (String -> String) | Function to apply on the value. |
| -> Page a | Page to change |
| -> Page a | Resulting page |
Change a metadata value.
import Data.Char (toUpper) changeField "title" (map toUpper)
Will put the title in UPPERCASE.
Arguments
| :: String | Key to copy |
| -> String | Destination to copy to |
| -> Page a | Page on which this should be applied |
| -> Page a | Resulting page |
Make a copy of a metadata field (put the value belonging to a certain key under some other key as well)
Arguments
| :: String | Key in which the rendered date should be placed |
| -> String | Format to use on the date |
| -> String | Default value, in case the date cannot be parsed |
| -> Page a | Page on which this should be applied |
| -> Page a | Resulting page |
When the metadata has a field called path in a
folder/yyyy-mm-dd-title.extension format (the convention for pages),
this function can render the date.
renderDate "date" "%B %e, %Y" "Date unknown"
Will render something like January 32, 2010.
Arguments
| :: TimeLocale | Output time locale |
| -> String | Destination key |
| -> String | Format to use on the date |
| -> String | Default value |
| -> Page a | Target page |
| -> Page a | Resulting page |
This is an extended version of renderDateField that allows you to
specify a time locale that is used for outputting the date. For more
details, see renderDateField.