Records without named variables

Developers
1

I am doing intercansiter call using a candid interface and it seems like it wants me to produce a record without a named variable … I hav abstracted a use case here to define what I think I need to do?

  type MyType = {
    varName1 :Text;
    varName2 :Text;
  };

  public func showRecord() : async MyType {


    // mo code to populate:
    var myNewVar : MyType = {
      varName1 = "banana";
      varName2 = "orange";
    };

    return myNewVar ;

  } ; // end showRecord

running

dfx canister call nftmanager showRecord "()"

produces:

(record { varName1 = "banana"; varName2 = "orange" })

is there anyway to define the type without names? so I can produce :

(record {"banana"; "orange" })

the value I would submit to the other canister if I did a dfx call would not have the named values i.e

dfx canister call othercanister "(record {\"banana\"; \"orange\" })"
2

From the candid side, record always has field names, but if the field name is numbered consecutively starting from 0, we can omit the field name as a shorthand. So record { 0 : text; 1 : text} can be written as record { text; text }. In Motoko, this type maps to tuple. For example,

    public func test(tuple: (Text,Text)) : async ((Text, Text)) {
        tuple
    }

The above function takes record { text; text } and returns record { text; text }

1 Like
3

THANK YOU … just learned something from you, so appreciate it, especially the code example …


  type MyType = (Text,Text );

  public func showRecord() : async MyType {


    // mo code to populate:
    var myNewVar : MyType = (
      "banana",
      "orange"
    );

    return myNewVar ;

  } ; // end showRecord

basically this works …
Really appreciate the quick response … got my head out the wall it was bangin’ against

4

It’s probably still better design to have names, though, to avoid confusing their order, make the API easier to understand etc.

5

The most common place to see it is in map structures. Rather than a K => V type, maps are represented in Candid as vec record { K; V; }

1 Like