Choosing datatypes for your fields
This page is for website creators who add attributes to classes. A datatype decides how a field is edited, stored, validated, searched and shown, and it cannot be changed later without migrating data. Choose by what you will do with the value.
Contents
The shipped datatypes
The datatypes available for new attributes are AvailableDataTypes[] in settings/content.ini; the shipped list has
35 entries:
| Group | Datatypes |
|---|---|
| Text | ezstring (Text line), eztext (Text block), ezxmltext (Rich text), ezidentifier, ezisbn |
| Dates and times | ezdate, ezdatetime, eztime |
| Numbers and yes/no | ezinteger, ezfloat, ezboolean |
| Choices | ezselection, ezenum, ezcountry, ezkeyword |
| Relations | ezobjectrelation (one object), ezobjectrelationlist (several) |
| Media | ezimage, ezbinaryfile, ezmedia |
| Contact and links | ezemail, ezurl, ezauthor |
| Structured | ezmatrix (a table) |
| Shop | ezprice, ezmultiprice, ezoption, ezmultioption, ezmultioption2, ezrangeoption, ezproductcategory |
| System | ezuser, ezsubtreesubscription, ezinisetting, ezpackage |
The implementations are in kernel/classes/datatypes/<name>/.
Choosing by need
| You need | Choose | Not |
|---|---|---|
| A title, a name | ezstring | ezxmltext |
| A teaser or summary shown in lists and meta tags | eztext | ezxmltext (markup in meta tags) |
| A body with headings, links, embedded images | ezxmltext (edited with the online editor) | eztext |
| A date to sort or filter by | ezdate or ezdatetime | text |
| A yes/no switch (featured, hide teaser) | ezboolean | a selection with two items |
| One or several choices from a fixed list | ezselection | free text |
| A country | ezcountry | ezselection with your own list |
| An image used once | ezimage in the class | |
| An image reused in many places | ezobjectrelation to an Image object | a copy in each object |
| Several related items (authors, related articles) | ezobjectrelationlist | a text list of names |
| A download | ezbinaryfile | |
| A link to another site | ezurl | text |
| An e-mail address | ezemail (validated) | ezstring |
| A table of values | ezmatrix | rich text tables, when the values are data |
| Free keywords | ezkeyword, or better eztags from the eztags extension | |
| A price | ezprice (with VAT) or ezmultiprice (several currencies) | ezfloat |
Datatypes from extensions
Extensions add datatypes; they register them in their own settings. Examples documented here: eztags (a tag tree with autocomplete), enhancedselection2, enhancedezbinaryfile, ezgmaplocation (a map location), ezstarrating. A datatype of your own is an application creator's task (Writing a custom datatype).
Showing a field in a template
{attribute_view_gui attribute=$node.data_map.body}renders the field with its datatype's view template (content/datatype/view/<datatype>.tpl, overridable). For a plain
value, read .content or test .has_content:
{if $node.data_map.image.has_content}
{attribute_view_gui attribute=$node.data_map.image image_class='medium'}
{/if}Pitfalls
- Rich text where plain text is needed. Teasers in rich text end up as markup in feeds and meta tags.
- Numbers as text. Text sorts "10" before "9".
- Selections for things that change. Adding an option is easy; renaming one renames it in every object, and removing one leaves objects without a value. For a list editors maintain, use tags or relations.
- Copies instead of relations. A copied image or address must be updated in every copy.
- Old media datatypes. The Flash, QuickTime, Windows Media and RealVideo classes of older packages show content modern browsers do not play; use video files or embeds.
Related pages
- Designing your content model
- Relations and content reuse
- Images and image variations
- The datatype life cycle
- Free documentation: this page is free to copy, translate and improve under the GNU FDL 1.3.
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