From my understanding of javascript, I should be able to query for map value using key using following code:

consts = {'key' : 'value'};
var stringKey = 'key';
var something = consts[stringKey];

However, when I try to use similar way of querying within an aura component to apply dynamic style for my button colour in the code below, I get an error.


<aura:iteration items="{!v.myObjs }" var="obj">
    <aura:iteration items="{!obj.myItems }" var="objItem">
        <div class="slds-col slds-small-size_12-of-12 slds-medium-size_6-of-12">
            <button class="slds-button slds-button_neutral" style="{!'color:' + obj.btnColour[objItem.MyName__c]}" onclick="{!c.showFlow}" id="{!objItem.MyName__c}">{!objItem.MyText__c}</button>


FIELD_INTEGRITY_EXCEPTION - expecting a positive integer, found 'objItem' at column xx of expression: 'color:' + obj.btnColour[objItem.MyName__c]: Source

Am I doing anything wrong? I verified, I have my object correctly setup and it contains data as expected.

1 Answer 1


Am I doing anything wrong?


Simply, while JavaScript supports this syntax, "Aura Expressions" do not.

You need to mix the data together such that you can resolve it without using the "dynamic" notation, which means copying the value in a way that you can access it directly from obj.

Without seeing your code, it's hard to make a specific recommendation, but you'll need to restructure your data.

  • Yeah, whenever I need to do this sort of thing, I usually create a change handler on my object attribute, define a second attribute to contain an array of objects (type="Object[]"), then in my change handler, populate the second attribute with an array of objects built from iterating over the keys. That array of objects then is able to be used in aura:iteration Commented Jan 31, 2020 at 17:45

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