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~Karl Kiresalitnivu
Nov 8, 2012, 10:09 PM
13 Posts
topic has been resolvedResolved

viewScope variable binding question

  • Category: Server Side JavaScript
  • Platform: Windows
  • Release: 8.5.3
  • Role: Developer
  • Tags:
  • Replies: 3
My viewScope variable is getting updated when I update a variable that was initiated with the value of the viewScope variable. Is this the expected behavior? I haven't noticed this happening before (perhaps I've never had this exact scenario), but I would like to fully understand how this is intended to work so that I can code appropriately.
 
Here's my code: 
 
1) I set a viewScope variable when the page loads as follows -- the value should never be updated unless the user refreshed the whole page: 

<xp:this.beforePageLoad><![CDATA[#{javascript:

var result = DbLookupArray('', applicationScope.mainDBPath, 'cache', 'unique', '', 'lvwUserProfilesbyRole', "Leasing Agent", 4);

if (result) {

var dmData:java.util.HashMap = new java.util.HashMap;

for (var dm in result) {

colKey = @Word(dm, "^", 1);

fullName = @Word(dm, "^", 2);

dspName = @Word(dm, "^", 3);

if (@Text(colKey) != ""){

colVals = dmData.get(colKey);

if (colVals == null){

dmData.put(colKey, {SN: colKey, DN: dspName, FN: fullName, TotDeals: 0, TotLseRev: 0, TotBgtRev: 0, NewDeals: 0, NewLseRev: 0, NewBgtRev: 0, LTDeals: 0, LTLseRev: 0, LTBgtRev: 0, VACDeals: 0, TotGLA: 0, DeadDeals: 0});

}}}

viewScope.statistics_Ranking_DMData = dmData;  }]]></xp:this.beforePageLoad>

 
2) Within a custom control, I run the following code (looping through a json array) to populate values. Note, I only want to update my code variable (dmData) and not the viewScope variable:

var dmData = viewScope.statistics_Ranking_DMData;

for (i = 0; i < jsonValues.length; i++) {

colKey = jsonValues[i].SRanking_Leasing_Agent_SN;

dspName = jsonValues[i].SRanking_Leasing_Agent_Dsp;

fullName = jsonValues[i].SRanking_Leasing_Agent;

colVals = dmData.get(colKey);

if (colVals == null){

dmData.put(colKey, {SN: colKey, DN: dspName, FN: fullName, TotDeals: 0, TotLseRev: 0, TotBgtRev: 0, NewDeals: 0, NewLseRev: 0, NewBgtRev: 0, LTDeals: 0, LTLseRev: 0, LTBgtRev: 0, VACDeals: 0, TotGLA: 0, DeadDeals: 0});

colVals = dmData.get(colKey);

}

deadDeals = colVals.DeadDeals + jsonValues[i].SRanking_Dead_Deals;

totDeals = colVals.TotDeals + jsonValues[i].SRanking_Total_Deals;

totLseRev = colVals.TotLseRev + jsonValues[i].SRanking_Total_Lse_Rev;

totBgtRev = colVals.TotBgtRev + jsonValues[i].SRanking_Total_Bgt_Rev;

newDeals = colVals.NewDeals + jsonValues[i].SRanking_New_Deals;

newLseRev = colVals.NewLseRev + jsonValues[i].SRanking_New_Lse_Rev;

newBgtRev = colVals.NewBgtRev + jsonValues[i].SRanking_New_Bgt_Rev;

ltDeals = colVals.LTDeals + jsonValues[i].SRanking_LT_Deals;

ltLseRev = colVals.LTLseRev + jsonValues[i].SRanking_LT_Lse_Rev;

ltBgtRev = colVals.LTBgtRev + jsonValues[i].SRanking_LT_Bgt_Rev;

vacDeals = colVals.VACDeals + jsonValues[i].SRanking_VAC_Deals;

totGLA = colVals.TotGLA + jsonValues[i].SRanking_Total_GLA;

dmData.put(colKey, {SN: colKey, DN: dspName, FN: fullName, TotDeals: totDeals, TotLseRev: totLseRev, TotBgtRev: totBgtRev, NewDeals: newDeals, NewLseRev: newLseRev, NewBgtRev: newBgtRev, LTDeals: ltDeals, LTLseRev: ltLseRev, LTBgtRev: ltBgtRev, VACDeals: vacDeals, TotGLA: totGLA, DeadDeals: deadDeals});

}

 
 
3) The issue is that once the code in #2 executes, my viewScope variable has been updated as well. I've found that I can make this change to the first line of code #2 to fix the issue: 

var dmData = viewScope.statistics_Ranking_DMData.clone();

 
However, I'm concerned because I have tons of code where I initialize variables based on viewScope variables so I'm trying to figure out if this is something I've been coding incorrectly all this time (and I need to use the "clone()" on all of them), or is this just a unique situation where this is causing an issue for me. 

Can someone clarify this for me? 

Thanks so much! 

Crista 

~Karl Kiresalitnivu
Nov 8, 2012, 10:12 PM
13 Posts
Re: viewScope variable binding question
P.S. The "DBLookupArray" function is a very nifty function written by Tom Steenbergen. It works much like the standard DBLookup but it's a little nicer. You can find it with a google search. :)
~Alexis Opresaman
Nov 9, 2012, 6:27 AM
129 Posts
Re: viewScope variable binding question
When you bind an object/array to a variable, you pass the reference to the object. 
 
E.g.
viewScope.a = [1,2]; 
var b = viewScope.a; 
b.push( 3 ); 
 
// viewScope.a -> [1,2,3]
// b -> [1,2,3] 
 
 
If you're dealing with boolean, string or number, I believe you're safe. As you discovered, cloning the object is the way to go if you want a shallow copy of the object. You can run into issues with shallow copies (clone) as well if you're copying objects that contain other objects. 
 
More information about shallow/deep copies: 
http://www.jusfortechies.com/java/core-java/deepcopy_and_shallowcopy.php 
~Karl Kiresalitnivu
Nov 9, 2012, 5:21 PM
13 Posts
Re: viewScope variable binding question
Wow, I can't believe I didn't know that. Yikes!
 
Thanks for the clarification and the link to more info. 
 
Cheers!

This forum is closed to new posts and responses. Individual names altered for privacy purposes. The information contained in this website is provided for informational purposes only and should not be construed as a forum for customer support requests. Any customer support requests should be directed to the official HCL customer support channels below:

HCL Software Customer Support Portal for U.S. Federal Government clients
HCL Software Customer Support Portal