Handling BLOBs

by Michela Frigerio
6,744 views Published on Oct 24, 2011
Applies to: All versions
Table of contents

In the Domain Model you can define BLOB attributes. This attributes are objectified using an instance of a particular object implementing the RTXBLOBData interface. This type of object permits to access some properties of the wrapped BLOB:

  • Name: the file name.
  • Length: the file size in bytes.
  • Extension: the file extension.

You can use the following data unit template to see BLOB information.

[% def file = unit.selectSingleNode("layout:Attribute[@name='file']") %]



upload path: ${<wr:UnitId/>.data.[%= getFieldName(file)%]}

name: ${<wr:UnitId/>.data.[%= getFieldName(file)%].name}

length: ${<wr:UnitId/>.data.[%= getFieldName(file)%].length}

extension: ${<wr:UnitId/>.data.[%= getFieldName(file)%].extension}    

In the Web page you will see something like:

upload path: /upload/ent1/1/test.pdf

name: test.pdf

length: 2000

extension: pdf

The following code according to the Storage Type:

${<wr:UnitId/>.data.[%= getFieldName(file)%]}

represents

  • The path of the file stored on the file system under the Web Application "upload" folder, if the BLOB Attribute is stored on the file system.
  • A query string describing how to retrieve the BLOB binary data, if the BLOB Attribute is stored on the database.

A working example

For example if you want to render an image into the HTML page you can use one of the following templates depending on the chosen Storage Type

  • BLOB stored on file system:
<a href="${<wr:UnitId/>.data.[%= getFieldName(file)%]}">

  <c:out value="${<wr:UnitId/>.data.[%= getFieldName(file)%].name}"/>

</a>

  • BLOB stored on the database:
<a href="<webratio:BLOB value="${<wr:UnitId/>.data.[%= getFieldName(file)%]}"/>">

  <c:out value="${<wr:UnitId/>.data.[%= getFieldName(file)%].name}"/>

</a>
 
 

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