[rules-users] Drools Guvnor: DSL with multiple fact fields conditions using "-" and eval

[Patricia Bogoevici]

Thx for your answer.

I tried again the rule, removing the extra space after hyphen from DSL expresion. No luck. So, I tried a few more cases, and the only one that worked correctly was #3. 
It seems to me that is somehow related to the parenthesis, although it might be something else. Hope this info helps. 

1) only eval:
DSL:
[when] There is an Asset=asset:Asset()
[when]-name is empty=eval(name=="''")
[when]-tag is empty=eval(tag=="''")

Rule source:
    rule "test_rule"
    dialect "mvel"
        when
            asset:Asset( eval(name=="''", eval(tag=="''") ) )
        then
    end

2) no eval, but with the parenthesis:
DSL:
[when] There is an Asset=asset:Asset()
[when]-name is empty=(name=="''")
[when]-tag is empty=(tag=="''")

Rule source
    rule "test_rule"
    dialect "mvel"
        when
            asset:Asset( (name=="''", (tag=="''") ) )
        then
    end

3) simple case
DSL
[when] There is an Asset=asset:Asset()
[when]-name empty=name=="''"
[when]-tag empty=tag=="''"

Rule Source:
    rule "test_rule"
    dialect "mvel"
        when
             asset:Asset( name=="''", tag=="''" )
        then
    end

Thanks,

--- On Thu, 8/26/10, Mauricio Salatino <salaboy at gmail.com> wrote:

From: Mauricio Salatino <salaboy at gmail.com>
Subject: Re: [rules-users] Drools Guvnor: DSL with multiple fact fields conditions using "-" and eval
To: "Rules Users List" <rules-users at lists.jboss.org>
Date: Thursday, August 26, 2010, 10:43 PM

can you try with this:
[when] There is an Asset=asset:Asset()
[when] -name is 
empty=eval(StringUtils.isBlank(name))
[when] -tag is 
empty=eval(StringUtils.isBlank(tag))

2010/8/26 Patricia Bogoevici <patriciabogoevici at yahoo.com>


Hi all,

I am using the latest Guvnor release (5.1), and I have the following DSL expression where I use "-" to have conditions on multiple lines:

[when] There is an Asset=asset:Asset()
[when]- name is empty=eval(StringUtils.isBlank(name))

[when]- tag is empty=eval(StringUtils.isBlank(tag))

Having these DSL expressions, I wanted to create a rule, but I ran into some issues. 
To summarize: There seems to be a parsing error, when conditions are added in DSL using "-".  Did anybody else run into this problem? I wonder if I do something wrong, but, re-creating the DSL to have the 2 conditions into one expression, is all working fine. It may be a combination of "-" and eval? 


Below, is the description of rules created, and error I got.

First, I created a rule using the above DSL expressions in the BRL editor. While the
 rule looked ok in the editor, and it validated fine, only when I checked the source I noticed is wrong. So, the rule source looks like this:
rule "test_dsl"
        dialect "mvel"
        when

            asset:Asset( eval(StringUtils.isBlank(name, eval(StringUtils.isBlank(tag)) )) )
        then
            asset.setStatus("INVALID")
    end

It looks that the conditions are parsed incorrectly, and the second eval condition is added as a parameter to the StringUtils.isBlank from the first eval. Also, all the right parenthesis are added at the end of the expression. If I add one condition at a time, it all works fine. The error is when I have more than 1 condition. 


So, I created a new DSL, that contains both
 conditions into one line, eliminating the hyphen between conditions:

[when] There is an asset with name empty AND tag empty =asset:Asset(eval(StringUtils.isBlank(name)),eval(StringUtils.isBlank(tag)))

Using  BRL editor, I created a second rule using the DSL above. The rule validated ok, and the rule source looks fine:


rule "test_dsl_1"
        dialect "mvel"
        when
            asset:Asset(eval(StringUtils.isBlank(name)),eval(StringUtils.isBlank(tag)))
        then
            asset.setStatus("INVALID")

    end

I created a test for this rule, that ran correctly.


Thanks,
Patricia



      
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