Is it possible to fetch a CDT field by numerical index?

Question

Hi all, 
 I want to get fields in a CDT based on their numerical index, i.e. if I have a CDT like:

{'type!{urn:com:appian:types:TEST}TEST_Employee'('firstName': "Frank", 'secondName': "Smith", 'age': 29)} 
 To get the first field, is there a way to index it by number? Something like index(local!testCdt, 1, null) would return "Frank". 
 Thanks for your help!

Harshit Bumb (Appyzie) · Accepted Answer

Change the value of the local!index variable to your desired index. 
 a!localVariables(
 local!data: 'type!{urn:com:appian:types:DA}DA_Student'(
 firstName_txt: "Harshit",
 lastName_txt: "Bumb"
 ),
 local!keys: a!keys(local!data),
 local!index: 3,
 local!selectedkey: index(local!keys,local!index,{}),
 index(local!data,local!selectedkey,{})
)

Stefan Helzle · Answer

If you plan to persist this, go with a CDT and add a primary key field. 
 But you can also store the list of maps in a PV and transform it into CDT later on.

Mike Schmitt · Answer

johng0005 said: How would I keep this persisted in a key-value fashion? 
 You can do pretty much whatever you want if you use an expression rule, FWIW 
 The beauty of that is, you can design an expression rule using a "black box" approach, such that you can start out with hardcoded or even "faked" values, and if/when you decide to shift to a DB-backed approach, you can simply update that expression rule to do whatever internal querying it needs to do, in order to return the same values based on the input passed in.

Is it possible to fetch a CDT field by numerical index?

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