Editing Date field

{{fieldtypes}}


== Description ==
This field is used to store a single date. Internally EPrints always uses ISO standard notation for dates, it avoids confusion. This is <tt>YYYY-MM-DD</tt>.

In bibliographies sometimes exact dates of publication (or other events) are not known. EPrints allows you to store month and year values in date fields. <tt>YYYY</tt> or <tt>YYYY-MM</tt>.

In the database EPrints actually uses 3 integer fields to store the date, rather than a built in date field. This is because of the need to allow <tt>NULL</tt> in month and day if the date is just <tt>1998</tt>.

== Inheritance ==
* [[Metadata]]
** [[Date field]]

== Additional Properties ==
{| border="1" cellpadding="3" cellspacing="0"
! Name !! Default Value !! Required !! Description !! Notes
|-
| '''input_style''' || <tt>long</tt> || NO || Whether to render the date inpit fields using longer or shorter month labels. || Can be <tt>short</tt> or <tt>long</tt>. The former is useful if you have limited width in your input form, especially if you are using a date field in a [[Compound field]].
|-
| '''min_resolution''' || <tt>day</tt> || NO || The minimum resoltion of date that must be entered.  Can be <tt>day</tt>, <tt>month</tt> or <tt>year</tt>. || If set to <tt>day</tt> then values of <tt>YYYY</tt> or <tt>YYYY-MM</tt> will cause a validation error. If set to <tt>month</tt> then values of <tt>YYYY</tt> will cause a validation error. If set to <tt>year</tt> then day, month or year resolutions are allowed.
|-
| '''render_res''' || <tt>day</tt> || NO || The resolution to render the date stored by this field. Can be <tt>day</tt>, <tt>month</tt> or <tt>year</tt>. || If set to <tt>year</tt> then the dates <tt>1998-10-01</tt>, <tt>1998-10</tt> and <tt>1998</tt> would all be rendered as <tt>1998</tt>. This is not too useful in configuring the field, but can be set as a print option inside citation files.
|-
| '''render_style''' || <tt>long</tt> || NO || The resolution to render the date stored by this field. Can be <tt>short</tt>, <tt>long</tt> or<tt>dow</tt>. || If <tt>long</tt> then you'll see <tt>8 September 1998</tt>. If <tt>short</tt> then <tt>08 Sep 1998</tt>.  <tt>dow</tt> would render <tt>Tuesday 8 September 1998</tt>.
|}

== Required Phrases ==
No additional phrases beyond the [[Metadata#Required_Phrases|standard metadata field phrases]].

== Database ==
Date fields are stored in the database as:

 fieldname_year SMALLINT(6)
 fieldname_month SMALLINT(6)
 fieldname_day SMALLINT(6)

If a date only has a year value then it would be stored as 1998,NULL,NULL

== API ==
See [[API:EPrints/MetaField/Date|API page]].

Date values are represented in the API as scalars containing ISO encoded dates. eg.

 "1976"
 "1976-02"
 "1976-02-02"

=== Searching ===
Date fields can be searched as either single values or ranges. Searching for <tt>2006><tt> will also match <tt>2006-12-25</tt>. You can search for <tt>2000-</tt> to search dates in or after 2000. Or <tt>2000-12-2003-01</tt> for December 2000 through January 2003.

== Examples ==
Most basic example.
 {
     name => 'acceptance_date',
     type => 'date',
 }
Set minimum resolution to which the date must be specified is at least a <tt>month</tt>.
 {
     name => 'moratorium_date',
     type => 'date',
     min_resolution => 'month',
 }
Set resolution to render to the <tt>month</tt>, set rendering style to <tt>short</tt> (e.g. Feb 2023).
 {
    name => 'publication_date', 
    type => 'date', 
    render_res => 'month', 
    render_style => short',
 }