I just want to ask if there’s a function that converts Daml template data to Json format. I have these code for example :
template Log with
message : Text
owner : Party
where signatory owner
templtate OtherData with
data1 : Text
data2 : Text
.. -- more data
-- assume variable od is a data from OtherData
create Log with
message = show od
In the UI, the field message is a text format, but It’s a bit complicated to parse it to JSON Object as the show function gives a different format data.
Is there a way or tool I can used to convert od into JSON format data, instead of show?
daml repl has a
:json command, e.g.,
daml> :json (1,2)
At the moment you cannot access it within your Daml code though or from client libraries.
Ok, so the solution is not to use show and format it properly so that JSON.parse it properly.
One way to print a JSON with the contract payload is the following:
- Create a choice on the contract which returns the payload (not the contract id which we usually need).
- Start Sandbox and create a contract instance.
- Exercise the choice with Postman, the API call will return the contract payload (the return value of the choice) in JSON format. (Alternatively, you can create a Daml Script which exercises the choice, and run the Daml Script with the
daml script command, specifying a filename with the
--output-file option. The command will print the JSON into this file.)
The choice mentioned in #1 is like the
PrintPayload choice on the following template:
type AssetId = ContractId Asset
issuer : Party
owner : Party
name : Text
ensure name /= ""
choice Give : AssetId
newOwner : Party
do create this with
owner = newOwner
nonconsuming choice PrintPayload : Asset
do return this
If you don’t want to write an extra choice for this, you can also use the
queryContractId command to retrieve the contract payload after creating the contract in the same Daml Script:
setup : Script Asset
setup = script do
alice <- allocatePartyWithHint "Alice" (PartyIdHint "Alice")
aliceTV <- submit alice do
createCmd Asset with
issuer = alice
owner = alice
name = "TV"
Some asset <- queryContractId alice aliceTV
Thought I’d follow up here instead of starting a new thread. Has this changed in the past year? Is there a function in the standard library to convert an arbitrary Daml type into a JSON string?
Can’t find anything on https://hoogle.daml.com.
There is still no standard functionality for this unfortunately.