Grid help: editable grid and read only grid

Question

Hi Appian community I am trying to add a value on to an editable grid 
 like this: 
 
 however my problem is when I try and access the 0's I get this error

I have tried to instantiate all the values as 0 but the array does not seem to register 
 
 here is my code thus far for my integer field 
 a!integerField( value: and(if(isnull(ri!rank),0,ri!rank[fv!index]), if(length((ri!rank)>fv!index),0,ri!rank[fv!index]) ), saveInto: ri!rank[fv!index], required: true ) 
 
 any assistance would be greatly appreciated,

Mike Schmitt · Accepted Answer

The problem is, you're setting the value directly to the result of the evaluation of the and() expression, which is a boolean (true/false) value only, and I expect that's not what you actually want. You probably just want to make use of the index() function (no relation to fv!index which you're already using), which inherently ensures the position you're accessing actually exists within the array. 
 value: index(ri!rank, fv!index, 0),

Mike Schmitt · Answer

As a general tip, when posting long code like this, please use the Insert --> Insert Code functionality and paste your code into the provided text box - this helps with keeping formatting/indentation straight, as well as preventing the post from being overwhelmed by pages and pages of code unnecessarily. 
 Also: the reasoning behind the more recent error message you screenshotted, seems to be an extra "(" in your length() function call: length((ri!rank)>fv!index) -- here, instead of getting the length of ri!rank and comparing it to fv!index like you intended, you're actually attempting to get the length of ( ri!rank > fv!index ), which is invalid since ri!rank is an array and therefore the ">" comparison is invalid. 
 This would be easier to troubleshoot if you use more standard linebreaks and indentation in your logic, i.e. more like this: /* this contains no changes other than adjusted linebreaks and indentation, for clarity and readability */
a!integerField(
 value: or(
 if(
 isnull(ri!rank),
 0,
 ri!rank[fv!index]
 ),
 if(
 length((ri!rank) > fv!index),
 0,
 ri!rank[fv!index]
 )
 ),
 saveInto: ri!rank[fv!index],
 required: true
) 
 In the above we can see that this code is still fundamentally problematic (as i noted in my reply further down-thread); you're setting the value of the integer field to the result of the or() expression (i guess you changed this from your earlier and() call), but here the result will still be a boolean value, which I'm not sure is your intention (unless ri!rank itself is a boolean value which is unclear). The length() expression call can be fixed by removing the unnecessary set of parenthesis, like this: length(ri!rank) > fv!index . However I think you might actually just want to replace this whole expression with a single instance of the index() function like I described in my earlier reply below.

Grid help: editable grid and read only grid

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