Domino Design Code Injection

In an earlier entry I discussed how to maintain custom system databases. It works well when you add design elements or change them wholesale. However it doesn't work very well when you tweak design elements. Something like: adding one action in a form or using a different subform for a specific task. Once an updated system template is available, you have to go back and recreate all your changes in your template.
This entry discusses how to automate these little fixes. There are a number of moving parts involved:

1. Export the design element using DXL. (You might need to set NotesDXLExporter.RichTextOption = RICHTEXTOPTION_RAW to make sure the fidelity of forms is maintained)
2. Locate the entry/replace point. The best mechanism for that is XPath
3. Locate the new code. This could be as easy as provide a string with the XML Snippet to pointing to an existing design element elsewhere. (We would use XPath again)
4. Perform the insertion/replacement. We will have the option: before/after/replace
5. Write back your changes and test it

What type of code injections come to my mind:

• Add an action to a form/view
• Add a subform to a form
• Replace a validation formula in a field
• Insert a script library and a custom class into a form
• Add a field at the top or bottom of a form (our favorite hidden fields $$Return anyone

Understanding DXL and XPath is key to make this work. As a Domino developer (and you are one? Otherwise all this might sound Greek and Latin to you) you have seen DXL and its description in the help file. XPath might be less familiar. In a nutshell: XPath is to XML what SQL is to relational data. When you develop XML Stylesheets (a.k.a. XSLT) you use XPath selectors to define your template matches. XPath is a set language, so you better remember your kindergarden days (give me all shapes that are blue, triangle and big). It is easy to get an overview and to get started and can get as complex as you can take it. One little caveat (you see Latin is creeping it): XPath is case sensitive
Some simple examples:

• * selects ANY element.
• / selects the root element, basically before any tags in the XML
• /database/form/actionbar selects the actionbar elements in all forms in our XML
• /database/form[1]/actionbar selects the actionbar element in the first form in our XML
• /database/form[@name='Message']/actionbar selects the actionbar element in the form Message in our XML
• /database/form[@name='Message'] //field[@name='Subject'] /code[@event='defaultvalue'] /formula Select the default value formula for the field "Subject". Please note the double slashes in front of the field. They are intentional. One slash says: a child, two slashes says any decendant down the document. Also: no spaces before/after the slashes. They are here for readablitity only.
• //field[code/@event='inputvalidation'] Any field that has an input validation formula

You get the idea. You want to have a good XML editor.First you need a routine that can pull out a design element and write it back. Here is the example for a form:

 
Sub InjectCodeIntoForm

(formName

AsString, xPath

AsString, codeSnippet

AsString)'Errorhandling omitted for clarityDim s

AsNewNotesSessionDim db

AsNotesDatabaseDim f

AsNotesFormDim out

AsNotesStreamDim ex

AsNotesDXLExporterDim importer

AsNotesDXLImporterDim col

AsNotesNoteCollection'The strings holding the DXLDim rawDXL

AsStringDim resultDXL

AsStringSet db

= s

.CurrentDatabase

'Create a Note collection and add the formSet col

= db

.CreateNoteCollection

(False)Set f

= db

.GetForm

(formName

)
col

.BuildCollection

Call col

.Add

(f

)'Create the exporter and run the stuff outSet ex

= s

.CreateDXLExporter

Set out

= s

.CreateStream
ex

.RichTextOption

= RICHTEXTOPTION_RAW

'This is to get rawitems for untranslatable stuff
ex

.ValidationStyle

= VALIDATIONSTYLE_NONE

'To make sure we don't generate a schema referenceCall ex

.setinput

(col

)Call ex

.setOutput

(out

)
ex

.process

'Reset the stream and manipulate the DXL
out

.Position

= 0
rawDXL

= out

.ReadText
resultDXL

= injectCode

(rawDXL

, xPath

, codeSnippet

)'Write it back
out

.Truncate

Call out

.WriteText

(resultDXL

)
out

.Position

= 0

Set importer

= s

.CreateDXLImporter

'Having the right importer options is important
importer

.CompileLotusScript

=True
importer

.ReplaceDBProperties

=False
importer

.ReplicaRequiredForReplaceOrUpdate

=True
importer

.ACLImportOption

= DXLIMPORTOPTION_IGNORE
importer

.DesignImportOption

= DXLIMPORTOPTION_REPLACE_ELSE_IGNORE

'We only want to update the current form
importer

.DocumentImportOption

= DXLIMPORTOPTION_IGNORE

'This is for design only
importer

.ExitOnFirstFatalError

=False'Standard import executionCall importer

.setInput

(out

)Call importer

.setOutput

(db

)OnErrorResumeNextCall importer

.Import

Msgbox importer

.logEndSub
 

Now we need a pice of code that can do the transformation of the DXL. Unfortunately the LotusScript XML Parser is lacking, so we use some Java code to perform this step. After creating the class (without parameters, for LS2J comfort, we need to set the DXL as Document and then call injectCode with 3 parameters: xPath expression, codeSnippet to insert (must be an XML fragment) and insertion type (before/after/replace). See Part 2 for the Java code.