#parse($stringValue)

[Scott Eade <se...@backstagetech.com.au>]

What is the appropriate way to go about parsing the contents of a 
variable?  

A couple of examples:

1. What if my application's skin defines some text to be replaced 
that is then used in another skin variable?
    adminTitle = Systems Administrator
    contactMsg = Please contact your $ui.adminTitle if you encounter problems.

2. What if I want to save a ui variable to the database - e.g. I want 
to be able to save and edit my help text as part of my application.  In 
order to do this, my help text will need to use $ui.adminTitle.


How do I go about parsing the following terms so that $ui.adminTitle is 
displayed as "System Administrator"?

       $ui.contactMsg
        $SomeDBObject.SomeColumn (data contains $ui.adminTitle)

Thanks,

Scott

Re: #parse($stringValue)

[Scott Eade <se...@backstagetech.com.au>]

From: "Geir Magnusson Jr." <ge...@optonline.net>
> Scott Eade wrote:
> > 
> > 
> > I think my second example may however still be relevant in the context
> > of just velocity.  What I want is to be able to retrieve some data from
> > a database that includes a context reference - e.g. in the database the
> > column for a specfic row may be:
> > 
> >     Contact the $adminTitle for help.
> > 
> > Then with this:
> > 
> >     #set($adminTitle = "System Administrator)
> > 
> > in the context I want to retrieve the data from the database and have
> > it output:
> > 
> >     Contact the System Administrator for help.
> > 
> > The string that needs to be parsed for variables is the one being retrieved
> > from the database.
> 
> Ok - the doublequote string literal won't work, because velocity doesn't
> "recurse" on string lits to interpolate.  (This ain't Perl)
>  
> > The only way I can currently see to make this work is to retrieve the
> > data nto a temporary file and then #parse() it.  I was hoping there might
> > be a more direct way.
> 
> There is - the org.apache.velocity.app.Velocity (and VelocityEngine)
> have an evaluate() method that will allow you to do to a String or
> InputStream what #parse() does to templates.
> 
> So make a little wrapper around it and then you can do it in your
> template to your heart's delight :
> 
> #set($dbstring = $dbtool.getColumn(<whatever>)
> 
> (so I assume $dbstring contains "Contact the $adminTitle for Help")
> 
> and then
> 
> #set($adminTitle = 'System Administrator')
> 
> #set($completestring = $yourtool.eval($dbstring) )
> 
> 
> The evalualte() method needs a context, so either make sure you stuff
> the current context into it when putting it in the context, or make it
> context agnostic, put a reference to the context in the context, and
> then
> 
> #set($completestring = $yourtool.eval($context, $dbstring) )
> 
> 
> I would assume this tool might already exist in the 'rupert' project in
> commons-sandbox - so look there first.  If not, that would be a great
> one to contribute to there :)
> 
> geir
> 


Geir,

That puts me on the right track.

Thanks a million,

Scott

Re: #parse($stringValue)

["Geir Magnusson Jr." <ge...@optonline.net>]

Scott Eade wrote:
> 
> 
> I think my second example may however still be relevant in the context
> of just velocity.  What I want is to be able to retrieve some data from
> a database that includes a context reference - e.g. in the database the
> column for a specfic row may be:
> 
>     Contact the $adminTitle for help.
> 
> Then with this:
> 
>     #set($adminTitle = "System Administrator)
> 
> in the context I want to retrieve the data from the database and have
> it output:
> 
>     Contact the System Administrator for help.
> 
> The string that needs to be parsed for variables is the one being retrieved
> from the database.

Ok - the doublequote string literal won't work, because velocity doesn't
"recurse" on string lits to interpolate.  (This ain't Perl)
 
> The only way I can currently see to make this work is to retrieve the
> data nto a temporary file and then #parse() it.  I was hoping there might
> be a more direct way.

There is - the org.apache.velocity.app.Velocity (and VelocityEngine)
have an evaluate() method that will allow you to do to a String or
InputStream what #parse() does to templates.

So make a little wrapper around it and then you can do it in your
template to your heart's delight :

#set($dbstring = $dbtool.getColumn(<whatever>)

(so I assume $dbstring contains "Contact the $adminTitle for Help")

and then

#set($adminTitle = 'System Administrator')

#set($completestring = $yourtool.eval($dbstring) )


The evalualte() method needs a context, so either make sure you stuff
the current context into it when putting it in the context, or make it
context agnostic, put a reference to the context in the context, and
then

#set($completestring = $yourtool.eval($context, $dbstring) )


I would assume this tool might already exist in the 'rupert' project in
commons-sandbox - so look there first.  If not, that would be a great
one to contribute to there :)

geir

-- 
Geir Magnusson Jr.                           geirm@optonline.net
System and Software Consulting
Developing for the web?  See http://jakarta.apache.org/velocity/
Well done is better than well said - New England Proverb

Re: #parse($stringValue)

[Scott Eade <se...@backstagetech.com.au>]

From: "Jon Stevens" <jo...@latchkey.com>
> 
> From the documentation:
> 
> <http://jakarta.apache.org/velocity/developer-guide.html>
> 
> String Interpolation
> 
> runtime.interpolate.string.literals = true
> Controls interpolation mechanism of VTL String Literals. Note that a VTL
> StringLiteral is specifically a string using double quotes that is used in a
> #set() statement, a method call of a reference, a parameter to a VM, or as
> an argument to a VTL directive in general. See the VTL reference for further
> information. 
> 
> -jon
> 

I'm using turbine which uses true as the default value for the interpolate
string literals property.

Scott

Re: #parse($stringValue)

[Jon Stevens <jo...@latchkey.com>]

on 8/12/01 11:01 PM, "Scott Eade" <se...@backstagetech.com.au> wrote:

> Hmm, this doesn't seem to work for me here.  $foo is resolved to
> the content of $databaseContent, but any variables within it are not
> processed.  Using my example, I still get:
> 
>   Contact your $adminTitle for help.
> 
> Scott

>From the documentation:

<http://jakarta.apache.org/velocity/developer-guide.html>

String Interpolation

runtime.interpolate.string.literals = true
Controls interpolation mechanism of VTL String Literals. Note that a VTL
StringLiteral is specifically a string using double quotes that is used in a
#set() statement, a method call of a reference, a parameter to a VM, or as
an argument to a VTL directive in general. See the VTL reference for further
information. 

-jon

Re: #parse($stringValue)

[Scott Eade <se...@backstagetech.com.au>]

From: "Jon Stevens" <jo...@latchkey.com>
> 
> > The only way I can currently see to make this work is to retrieve the
> > data nto a temporary file and then #parse() it.  I was hoping there might
> > be a more direct way.
> 
> There is:
> 
> #set ( $foo = "$databaseContent")
> $foo
> 
> -jon
> 
Hmm, this doesn't seem to work for me here.  $foo is resolved to
the content of $databaseContent, but any variables within it are not
processed.  Using my example, I still get:

    Contact your $adminTitle for help.

Scott

Re: #parse($stringValue)

[Jon Stevens <jo...@latchkey.com>]

on 8/12/01 10:24 PM, "Scott Eade" <se...@backstagetech.com.au> wrote:

> The only way I can currently see to make this work is to retrieve the
> data nto a temporary file and then #parse() it.  I was hoping there might
> be a more direct way.

There is:

#set ( $foo = "$databaseContent")
$foo

-jon

Re: #parse($stringValue)

[Scott Eade <se...@backstagetech.com.au>]

Geir,

I understand the distinction between single and double quotes as used
in this context, but this isn't quite what I am after.

My first example uses Turbine's UIManager - so this is not a good place
(i.e. the velocity mail list) to use it as an example.

I think my second example may however still be relevant in the context 
of just velocity.  What I want is to be able to retrieve some data from 
a database that includes a context reference - e.g. in the database the
column for a specfic row may be:

    Contact the $adminTitle for help.

Then with this:

    #set($adminTitle = "System Administrator)

in the context I want to retrieve the data from the database and have
it output:

    Contact the System Administrator for help.

The string that needs to be parsed for variables is the one being retrieved
from the database.

The only way I can currently see to make this work is to retrieve the
data nto a temporary file and then #parse() it.  I was hoping there might
be a more direct way.


Thanks,

Scott

Re: #parse($stringValue)

["Geir Magnusson Jr." <ge...@optonline.net>]

Scott Eade wrote:
> 
> What is the appropriate way to go about parsing the contents of a
> variable?
> 
> A couple of examples:
> 
> 1. What if my application's skin defines some text to be replaced
> that is then used in another skin variable?
>     adminTitle = Systems Administrator
>     contactMsg = Please contact your $ui.adminTitle if you encounter problems.
> 

Do you mean something like

#set($msg = "Please contact your $ui.adminTitle if you encounter
problems")

which will 'render' into $msg the string with the value of
$ui.adminTitle in the right place...

Double quotes in a directive/reference arg  will always force a render
of the context.  Single quotes won't :

#set($foo = 'hello')
#set($msg1 = "$foo")
#set($msg2 = '$foo')
$msg1
$msg2

will output

hello
$foo

> 2. What if I want to save a ui variable to the database - e.g. I want
> to be able to save and edit my help text as part of my application.  In
> order to do this, my help text will need to use $ui.adminTitle.
> 
> How do I go about parsing the following terms so that $ui.adminTitle is
> displayed as "System Administrator"?
> 
>        $ui.contactMsg
>         $SomeDBObject.SomeColumn (data contains $ui.adminTitle)

The same way should work : 

$SomeDBObject.SomeColumn("Contact $ui.adminTitle")

should pass 'Contact System Administrator' to the method 'SomeColumn(
String )' of the object refrenced by $SomeDBObject.

Hope I understood the question.

geir

-- 
Geir Magnusson Jr.                           geirm@optonline.net
System and Software Consulting
Developing for the web?  See http://jakarta.apache.org/velocity/
Well done is better than well said - New England Proverb