Trouble updating array with information from another array

Question

"I'm encountering an issue with updating an array in costAdjustments . The current code is setting the LengthOfMonth field to 6 for all items in the array, but I only want to update specific entries." 
 a!save(
 local!newEstimates2,
 local!newEstimates2: a!forEach(
 items: local!newEstimates,
 expression: a!update(
 fv!item,
 "costAdjustments",
 a!forEach(
 items: fv!item.costAdjustments,
 expression: a!update(fv!item, "LengthOfMonth", 6)
 )
 )
 )
) 
 This isn't exactly what I need. What I want to do is loop through newEstimates and pull data from local!uniqueContractPeriods , which contains three rows of data with the fields: period, periodType, startDate, endDate, noOfMonths, and noOfDays. When the contractPeriodNum in costAdjustments within newEstimates matches the period in uniqueContractPeriods , I want to update the LengthOfMonth in newEstimates with the value of noOfMonths from uniqueContractPeriods . Below is the code I've written. 
 a!save( 
 local!newEstimates2, 
 local!newEstimates2: a!forEach( 
 items: local!newEstimates, 
 expression: a!update( 
 fv!item, 
 "costAdjustments", 
 a!forEach( 
 items: local!uniqueContractPeriods, 
 expression: if( 
 fv!item.period = fv!item.costAdjustments.contractPeriodNum, 
 a!update( 
 fv!item, 
 "LengthOfMonth", 
 index( 
 local!uniqueContractPeriods.noOfMonths, 
 where( 
 tostring(fv!item.period) = tostring(fv!item.costAdjustments.contractPeriodNum) 
 ) 
 ) 
 ), 
 fv!item 
 ) 
 ) 
 ) 
 ) 
 ) 
 I am sure it is a simple fix, but I have been working on it for a long time, any assistance would be great. Thank you.

Stefan Helzle · Answer

Your a!save() call is wrong. You cannot assign a value inside the value attribute of a!save, like you try in line 3. I suggest to check the correct syntax for a!save().