DataSubset & Rule Reference Question

Question

Hi Team, 
 I had 2 simple questions which I wanted to post here. Please help me if anyone has the answers : 
 
 Context : 
 You are given a list of CDT / Dictionary / Map with a few fields, eg : 
 { { key: 12, val: "ABC" }, { key: 20, val: "DEF" }, { key: 30, val: "GHI" } } 
 Problem statement : 
 Get those CDTs which have key bw 10 & 25 
 
 My approaches : 
 I had 2 approaches, both of which I have a roadblock 
 
 I convert this to list to a data subset using toDataSubset function and then filter on this 
 I create a rule which takes this `key` as an RI and then returns true / false based on condition. I will use this rule in the filter function and use wherecontains to filter out which matches our condition

Questions : 
 Now for the approach 1, I had a question : how do I filter this custom data subset ? because I only see queryEntity and queryRecord but nothing to query this custom dataset 
 For approach 2 : is there a way we can eliminate the need of creating a different rule in the env and somehow use some function .. is it possible to create local functions in appian ? something like : 
 a!localVariables(
 local!a: (var){
 
 }
)

Harsha Sharma · Answer

Given its a dictionary/map then you would need to write it to database so that filtering can be done for approach 1. Personally as per my understanding of the usecase its too much hassle so simpler way is foreach. If you are expecting a large dataset (which is not mentioned in description) then I would go for involving database and approach 1. 
 Anyway to answer your questions: 
 1. 
 GautamShenoy said: how do I filter this custom data subset ? because I only see queryEntity and queryRecord but nothing to query this custom dataset 
 To filter you need to store data into database using CDT or records. Then you can query the dataset. 
 2. 
 GautamShenoy said: is there a way we can eliminate the need of creating a different rule in the env and somehow use some function .. is it possible to create local functions in appian ? something like 
 filter() needs a predicate so you need to have a rule/function which can be called here. We cannot create local functions as you are expecting!

Shubham Aware · Answer

GautamShenoy said: Now for the approach 1, I had a question : how do I filter this custom data subset ? because I only see queryEntity and queryRecord but nothing to query this custom dataset 
 You cannot filter a custom DataSubset directly; queryEntity/queryRecord work only on database/record entities. 
 GautamShenoy said: For approach 2 : is there a way we can eliminate the need of creating a different rule in the env and somehow use some function .. is it possible to create local functions in appian ? something like : 
 Does not support local or anonymous functions; separate expression rules are required for reusable logic. Recommend, Use inline filter expressions with conditions or separate rules to filter lists efficiently.