Problem with saving into array using a foreach

Question

I have an expression rule with the following code 
 ri!createdBy,
a!forEach(
items: ri!createdBy,
expression: rule!OBV_replaceNull(
fv!item,
loggedInUser()
)
)
), 
 
 I call it from an interface like this 
 rule!myER(createdby: cdtName.created_by), where cdtName is an array of cdt type 
 
 The problem is that every item in the resulting array contains all the values. So if it loops twice cdtname.created_by will look like this {username;username, username;username}. If I did just a save like this save(ri!createdBy, loggedInUser()) then it works fine. 
 Running the for each alone seems to return the correct result within the expression rule. However, it is once I add the save into the rule input that causes problems. Has anyone run into this problem and found a solution?

Mike Schmitt · Answer

In the off chance that you're able to restructure things slightly (maybe, i'm a little fuzzy on what your current nested structure actually is), I was able to get the following example to work for essentially your use case. Let me know if I got close at all ;-) 
 (disclaimer: I acknowledge that this ended up being functionally identical to the example supplied above by Krishna, though I came up with this independently... and i guess the main benefit of mine is that it can be tested in a blank Interface editor without additional hassle). 
 a!localVariables(
 local!testCdtArray: {
 {
 id: 1,
 user: "testUser1"
 },
 {
 id: 2,
 user: ""
 },
 {
 id: 3,
 user: "testUser2"
 }
 },
 
 a!sectionLayout(
 contents: {
 a!paragraphField(
 value: local!testCdtArray,
 readOnly: true()
 ),
 a!buttonArrayLayout(
 align: "START",
 buttons: a!buttonWidget(
 label: "test",
 saveInto: {
 a!forEach(
 local!testCdtArray,
 a!save(
 fv!item.user,
 if(isnull(fv!item.user), loggedInUser(), fv!item.user)
 )
 )
 }
 )
 )
 }
 )
)