[opencms-dev] Adding a custom form field to TemplateOne (v.6.2.2)

[Ellery Crane]

I am trying to add a custom form field to TemplateOne in OpenCms  
version 6.2.2. I have not found any documentation anywhere as to how  
to do this; I am working off of the existing instructions and  
documentation of the person who developed the custom form field code.  
I have three files:

CmsTextLabelField.class - A compiled class file of the java source for  
the new form field, which extends A_CmsField.

inputfield.xsd - A modified version of the existing file which adds  
the form field to the FieldType SelectorWidget configuration value.

custom_form_fields.properties - A single line of text which maps the  
new form field's label (used in inputfield.xsd) to the full class  
name.  It consists of this line:
FIELDS=textLabel:org.opencms.frontend.templateone.form.CmsTextLabelField

The instructions I have say the following:

inputfield.xsd goes into:
/system/modules/org.opencms.frontend.templateone.form/schemas/

CmsTextLabelField.class goes into:
/system/modules/org.opencms.frontend.templateone.form/classes/org/ 
opencms/frontend/templateone/form/

custom_form_fields.properties goes into:
/system/modules/org.opencms.frontend.templateone.form/classes/

When I put these files in these directories (within the workspace), I  
successfully see a new field in the select box when editing a form. It  
does not have the proper label, however; it shows as:
??? form.field.type.textLabel ???

When I  save the form and try to view it, I get a null pointer  
exception:

10 Apr 2008 14:10:08,156 ERROR [mplateone.form.CmsFieldFactory: 199]  
Unable to create form field class instance for type textLabel!
java.lang.NullPointerException
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:164)
	at  
org 
.opencms 
.frontend 
.templateone.form.CmsFieldFactory.getField(CmsFieldFactory.java:195)
	at  
org 
.opencms 
.frontend.templateone.form.CmsForm.initInputFields(CmsForm.java:1260)
	at org.opencms.frontend.templateone.form.CmsForm.init(CmsForm.java:627)
	at org.opencms.frontend.templateone.form.CmsForm.<init>(CmsForm.java: 
261)
	at  
org 
.opencms 
.frontend.templateone.form.CmsFormHandler.init(CmsFormHandler.java:294)
	at  
org 
.opencms 
.frontend.templateone.form.CmsFormHandler.<init>(CmsFormHandler.java: 
124)
	at  
org 
.apache 
.jsp 
.WEB_002dINF 
.jsp 
.offline 
.system 
.modules 
.org_opencms_frontend_templateone_form 
.pages.form_html_jsp._jspService(form_html_jsp.java:57)
	...

Looking through the source of both CmsForm and CmsFieldFactory for the  
version 6.2.2 of OpenCms, it appears that it is trying to instantiate  
the field by calling Class.forName() on the string "textLabel" rather  
than the full name of the class file (as specified in  
custom_form_field.properties).  How do I fix this? How do I make  
OpenCms read in the properties file? And, assuming I get that running,  
is this the standard way to add new form fields?  Is there any  
documentation on this process available somewhere?  I am an  
experienced Java developer, but I'm a newbie to OpenCms. Any help  
would be appreciated.

Thank you!

_________________________________
Ellery Crane - Bear Code
85 Granite Shed Lane - Unit 1
Montpelier, Vermont  05602
+1 802-225-1331
http://bear-code.com/



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