To convert from string to double you have to full back to java:

Something along the lines  of

$monto : eval(Double.parseDouble(this.get(“MONTO”)))

 

However even with doing this your rules are unlikely to work consistently as you expect.  Using equality tests on doubles is fundamentally unsafe as doubles aren’t represented exactly and may not exactly match the value you think you have.  Force instance 0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1 != 1.0 (dependent on floating point chipset etc).  If you are dealing with currency then it is far simpler and safer to just operate with integers and divide by 100 when you want to display the value.  The other alternative is to use BigDecimal which will store an exact representation but will probably require more work with getting your accumulate function correct.  Your last option is to use Math.abs(left-right) < 0.1 to see if they are approximately equal.  More details can be found here http://firstclassthoughts.co.uk/java/traps/java_double_traps.html

 

Thomas

 

 

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Yamil Bracho
Sent: 10 March 2010 14:27
To: Drools UserList
Subject: Re: [rules-users] Problems count and sumarizing data in facts

 

I solved the counting of detail lines this way:

 

rule "Contador de lineas detalle vs Header"

  salience 10

  when

       Number($count : intValue) from accumulate(

              $mp : Map(this["_TYPE_"] == "D"), count($mp))

       $map : Map(this["_TYPE_"] == "H",

                  this["NU_REGISTROS"] != $count)

  then

    System.out.println("NumRecs=" + $count);

    listBitacora.add(new BitacoraDTO($map.get("_NUMLINE_"),

                                          "El número del lineas de detalle (" + $count +

                                          ") no empareja con lo del encabezado (" + $map.get("NU_REGISTROS") + ")"));

 end

 

However, I still got problem with summarize the amounts. I wrote

 

rule "Sumatoria de lineas detalle vs Header"

  salience 10

  when

       Number( $total : doubleValue) from accumulate(

               Map(this["_TYPE_"] == "D",

               $monto : ((Number) this["MONTO"]),

               sum($monto)))

       $map : Map(this["_TYPE_"] == "H",

                  this["MT_TOTAL"] != $total)

  then

    System.out.println("TOTAL=" + $total);

    listBitacora.add(new BitacoraDTO($map.get("_NUMLINE_"),

                                          "Error en el Detalle: El número del lineas de detalle (" +  $total +

                                          ") no empareja con lo del encabezado (" + $map.get("NU_REGISTROS") + ")"));

 end

 

And i am getting  mismatched input" so my question is how to convert a string to double in this line "$monto : ((Number) this["MONTO"])," ?

 

TIA

 

Yamil

 

From: yamilbracho@hotmail.com
To: rules-users@lists.jboss.org
Date: Tue, 9 Mar 2010 17:41:43 +0000
Subject: [rules-users] Problems count and sumarizing data in facts

Hi, I have two kind of facts in a map.

There is a field called _TYPE_ (H)eader, D)etail)

In the Header line I have two String fields, one for the number of details lines ("NU_REGISTROS") and another for the sum of the detail line ("MT_TOTAL")

In the detail lines I only have a String field called "MONTO" 

 

I would like to build two rules. One to check the count of detail lines versus the field in the header line so I wrote :

 

rule "Contador de lineas detalle vs Header"

  salience 10

  when

       $numRecs : Number()

                from accumulate(Map(this["_TYPE_"] == "D", $d : this["_NUMLINE_"]), count($d))

       $map : Map(this["_TYPE_"] == "H",

                  this["NU_REGISTROS"] != $numRecs)

  then

    System.out.println("NumRecs=" + $numRecs);

    listBitacora.add(new BitacoraDTO($map.get("_NUMLINE_"),

                                          "Error en el Detalle: El número del lineas de detalle (" +  $total +

                                          ") no empareja con lo del encabezado (" + $map.get("NU_REGISTROS") + ")"));

 end

 

 However I always got "NumRecs=1" when i print out the value of $numRecs but I am absolute sure there is two details lines...

 

 Second when i try to sumarize the total field in the details line i got (MONTO in the detail line is a string):

 

 rule "Sumatoria de lineas detalle vs Header"

  salience 10

  when

       $total : Number()

                from accumulate(Map(this["_TYPE_"] == "D",

                                $monto : this["MONTO"]),

                                sum(eval(Double.valueOf((String) $monto ))))

       $map : Map(this["_TYPE_"] == "H",

                  this["MT_TOTAL"] != $total)

  then

    System.out.println("TOTAL=" + $total);

    listBitacora.add(new BitacoraDTO($map.get("_NUMLINE_"),

                                          "Error en el Detalle: El número del lineas de detalle (" +  $total +

                                          ") no empareja con lo del encabezado (" + $map.get("NU_REGISTROS") + ")"));

 end

 

 but I got

 Rule Compilation error : [Rule name='Sumatoria de lineas detalle vs Header']

        rule/Rule_Sumatoria_de_lineas_detalle_vs_Header_0.java (9:1313) : The method eval(Double) is undefined for the type Rule_Sumatoria_de_lineas_detalle_vs_Header_0

 

 

 

 Any help in those tow problems

 

 TIA

 

Yamil

 

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