|Holds text of arbitrary length|
|Provided by:||Semantic MediaWiki|
|Added in version:||1.0|
|Removed in version:||still in use|
|Datatype ID:|| |
|Table of Contents|
The datatype Text is used to store strings of arbitrary length, i.e. text. Since Semantic MediaWiki 1.8.0 this datatype depreciated datatype "String" for SMWSQLStore3 and replaced it entirely in Semantic MediaWiki 1.9.0. Thus it is now possible to use specific values in semantic queries, or to sort query results by such values. It has the following restriction:
If you want to store special character sequences like "
::", you need to store them using the parser function
#set, instead of using in-text annotation syntax "
[[Property::value]]" notation. Thus you cannot embed "regular" semantic annotations inside a text property.
You can use some wiki markup inside a text property such as runs of ' for bold and italic, and the markup will change the appearance of the text.
Since Semantic MediaWiki 1.0 you can use special property "Allows value" to restrict a property to a particular set of values. For example you could limit a property like "Status" to values like "Active", "Pending", etc. Since Semantic MediaWiki 2.4.0 special property "Allows pattern" lets you restrict values according to patterns matching regular expressions. Semantic MediaWiki 2.4.0 also added special property "Has uniqueness constraint" allowing to annotate a unique data value only once.
Searching within values
Since Semantic MediaWiki 1.8.0 the first 40 characters (if more than 72 characters were stored as property value) or all 72 characters (if a maximum of 72 characters were stored as property value) are searchable as explained on the help page about selecting pages.1 Searching within property values was not possible in earlier versions of Semantic MediaWiki (≤ 1.7.1).Semantic MediaWiki 3.0.0 introduces configuration parameter
SMW_FIELDT_CHAR_LONG3 making it possible to extend the searchable length as described here to 300 characters4 without relying on the full-text search feature.
In Semantic MediaWiki 1.8.0 only this datatype still had the old behaviour for data store
SMWSQLStore2 as explained on the help page for previous versions of Semantic MediaWiki. Starting with Semantic MediaWiki 1.9.0 you will have to change datatype declarations from datatype "String" to this datatype if you still have these on property pages since aliasing of "String" for "Text" may be removed in any later version of Semantic MediaWiki.
Comparing the datatypes "Page" and "Text"
|Table of comparison between properties of Type 'Page' and Type 'Text'|
|Property of Type 'Page'||Property of Type 'Text'|
|Characters permitted||Value has the naming restrictions that apply to page titles in MediaWiki. See the documentation at MediaWiki.org.||Value may contain arbitrary text, including markup (such as that for bold and italic)|
|Length of value permitted||Value may not be longer than 255 bytes, again because of restrictions that apply to page titles in MediaWiki||Value may be longer than 255 bytes|
|Use of values in query statements|
|Support for equivalent values?||Value can be made an alias of another 'Page' value. This is achieved using MediaWiki's #REDIRECT syntax, which is used to forward users from a variant page title to the target page.||Value cannot be made an alias of another 'Text' value.|
|Wildcards||Value accepts wildcards in queries||Value accepts wildcards in queries|
|Number of characters searchable (using wildcards and comparators)||Value is searchable for all 255 bytes||Value is searchable for the first 40 characters (if more than 72 characters were stored as property value) or 72 characters (if a maximum of 72 characters were stored as property value).|
|Inverse querying||Yes, property allows for inverse querying. In this way, a list of unique property values can be retrieved.||No, property does not allow for inverse querying. To retrieve a set of unique property values, see some alternative approaches listed here, which may or may not offer a solution.|
|Annotating values||Value cannot itself be annotated. However, the page associated with a value may hold semantic annotations and so it can be the basis for extended queries such as subqueries. In addition, it can be the target for another property-value pair, making it queryable in different contexts.||Value cannot itself be annotated. However, it can be the target for another property-value pair, making it queryable in different contexts.|
|Appearance of values in printout statements|
|Appearance without special formatting||Value returned by a query normally appears as a page link.||Value returned by a query is rendered as-is in wiki text. This means that markup, such as that for bold and italic (see above), is usually rendered, although there may be exceptions.|
|Special formatting||Value can be de-linked by setting the query parameter link= (available in most result formats) to none. Additional formatting is usually achieved by means of templates.||Additional formatting is usually achieved by means of templates.|
|Service links||Property supports service links||Property does not support service links|
Help:Type Text en 1.8
- Semantic MediaWiki: User mailing list thread " Unable to query over the last words of a long text value "
- Semantic MediaWiki: GitHub pull request gh:smw:1481
- Semantic MediaWiki: GitHub pull request gh:smw:2536
- Stack Overflow: Question 3489041: Mysql::Error: Specified key was too long; max key length is 1000 bytes