How to sort a CDT from another CDT source?

Question

Hi, 
 I've already had to sort a CDT and I could use this code below very useful. 
 However, how would you do to sort a CDT from another CDT source (without Query the DB)? Example : I need to sort the cdt1 on the cdtDocs.order field 
 cdt1 - id - ref - label - idDoc (references the cdtDocs .id field) cdtDocs - id - order - label 
 cast(
 typeof(local!cdt),
 todatasubset(
 local!cdt,
 a!pagingInfo(
 startIndex: 1,
 batchSize: -1,
 sort: a!sortInfo(
 field: local!field,
 ascending: local!ascending
 )
 )
 ).data
)

Peter Lewis · Answer

Here's one way I can think of, but it's kinda messy - basically you have to define a new variable with the ID of the first CDT and the order from the second CDT. Then, you sort it in the same way you showed above. Lastly, you restructure your original array using the changed sort order. 
 a!localVariables(
 local!data: {
 a!map(
 id: 1,
 name: "Name 1",
 nestedFieldId: 101
 ),
 a!map(
 id: 2,
 name: "Name 2",
 nestedFieldId: 102
 ),
 a!map(
 id: 3,
 name: "Name 3",
 nestedFieldId: 100
 )
 },
 local!orderData: {
 a!map(
 nestedId: 100,
 nestedName: "Test",
 order: 2
 ),
 a!map(
 nestedId: 101,
 nestedName: "Test again",
 order: 3
 ),
 a!map(
 nestedId: 102,
 nestedName: "Test another time",
 order: 1
 )
 },
 local!dataWithSortOrder: a!forEach(
 items: local!data,
 expression: a!map(
 id: fv!item.id,
 order: displayvalue(
 fv!item.nestedFieldId,
 local!orderData.nestedId,
 local!orderData.order,
 0
 )
 )
 ),
 local!sortedDataIds: todatasubset(
 local!dataWithSortOrder,
 a!pagingInfo(
 startIndex: 1,
 batchSize: -1,
 sort: a!sortInfo(
 field: "order",
 ascending: true
 )
 )
 ),
 a!forEach(
 items: local!sortedDataIds,
 expression: displayvalue(
 fv!item.id,
 local!data.id,
 local!data,
 {}
 )
 )
) 
 I'd probably only recommend this if you had a small number of items - generally the database is more efficient at sorting data, so it's good to use the capabilities from the DB if you can. Just curious - what is your use case? How are you using the data?