Code not behaving same when I used localVariable with fixed number, expressionrule

Can you please provide us with more info like the error message or something like output so that so that we can tell what wrong is going on.

In the first, second screen shots I am getting the required o/p where as in last screen shot, instead of getting an array o/p, I am just getting 1 as an o/p and which is of type List of Number (integer).

a!localVariables(
local!reviewkey: 2,
local!excludeKeys: if(
local!reviewkey = 2,
{ 1, 3, 4},
if(local!reviewkey = 5, { 1,3,4,5,6 }, {1,2,3 })
),
local!excludeKeys
)

o/p: 

-------------------

a!localVariables(
local!reviewkey: 5,
local!excludeKeys: if(
local!reviewkey = 2,
{ 1, 3, 4},
if(local!reviewkey = 5, { 1,3,4,5,6 }, {1,2,3 })
),
local!excludeKeys
)

o/p: 

----------------------

a!localVariables(
local!reviewkey: tointeger(index(rule!AB_getReviewKey(key: 100),"reviewkey",null())),
local!excludeKeys: if(
local!reviewkey = 2,
{ 1, 3, 4},
if(local!reviewkey = 5, { 1,3,4,5,6 }, {1,2,3 })
),
local!excludeKeys

)

O/P:

In the first, second screen shots I am getting the required o/p where as in last screen shot, instead of getting an array o/p, I am just getting 1 as an o/p and which is of type List of Number (integer).

a!localVariables(
local!reviewkey: 2,
local!excludeKeys: if(
local!reviewkey = 2,
{ 1, 3, 4},
if(local!reviewkey = 5, { 1,3,4,5,6 }, {1,2,3 })
),
local!excludeKeys
)

o/p: 

-------------------

a!localVariables(
local!reviewkey: 5,
local!excludeKeys: if(
local!reviewkey = 2,
{ 1, 3, 4},
if(local!reviewkey = 5, { 1,3,4,5,6 }, {1,2,3 })
),
local!excludeKeys
)

o/p: 

----------------------

a!localVariables(
local!reviewkey: tointeger(index(rule!AB_getReviewKey(key: 100),"reviewkey",null())),
local!excludeKeys: if(
local!reviewkey = 2,
{ 1, 3, 4},
if(local!reviewkey = 5, { 1,3,4,5,6 }, {1,2,3 })
),
local!excludeKeys

)

O/P:

Could it be that "local!reviewkey" is a list of integers in your last example?

Try the below snippet. This is a weird edge case in the evaluation of the comparison operator.

if({1} = 2, {1,2}, {3,4})

Yes Stefan. 

tointeger(index(rule!AB_getReviewKey(key: 100),"reviewkey",null()))

returning list of Number (integer)

You should amend rule!AB_getReviewKey to return a single item if the expected output is always single.  If it isn't, then you should use square brackets or index() when calling it in order to get a single value into your local variable.

Also, when posting code snippets (even short ones like this) please use a Code Box and make sure to paste indented code - it makes it much easier to read / mentally process for us.

a!localVariables(
  local!reviewkey: tointeger(
    index(  /* use index() to get an index (1) */
      property(rule!AB_getReviewKey(key: 100), "reviewkey", null()), /* use property() to get a property (.reviewKey) */
      1,
      null()
    )
  ),
  local!excludeKeys: if(
    local!reviewkey = 2,
    { 1, 3, 4},
    if(local!reviewkey = 5, { 1,3,4,5,6 }, {1,2,3 })
  ),
  
  local!excludeKeys
)

Thank you Mike for your help.