Hello! This is my first time posting here. I am new to DAML. I am trying to find how to extract data from JSON file to the ledger using DAML script. I am currently working on putting records of students into the ledger, using smart contract. Any advise/guidance is really appreciated.

The daml script command takes a --input-file flag that must be a JSON value with a structure that matches the type of the first (and only) argument of the script you’re running. Here is the documentation of daml script for full details . Does that help?

Thanks very much for your reply. I am still a bit lost on how the data structure that we defined in JSON can directly be applied to the elements within our script. For example, given the following JSON structure: { “album”: “The White Stripes”, “year”: 1999, “US_peak_chart_post”: “-” }, How ca…

You can write a daml script that returns the data type you’re expecting. Then if you use the --output-file argument of the daml script command, it’ll produce a json file in the format that the daml code is expecting.

And you can use the daml repl, like this: daml repl /path/to/darfile.dar daml> import AlbumModule daml> :json Album with album = "The White Stripes", year = 1999, usPeakChartPost = "-"

You can experiment with the correspondence between Daml data types and their JSON equivalent using the :json directive at the REPL . For example (look to the following for additional details): $ daml repl .daml/dist/t-0.0.1.dar --import t daml> let a = [Album with title = "first title", year = 12, …

Thank you very much for the example given. It is clear now.

Just another related question. How do include the data that we extracted into a template, and submit it as a transaction using createCmd?

You need to create a data declaration that matches the structure of your JSON file (or format your JSON file to match one of your data declarations). Once you have that declaration, including said data in a template is just adding an attribute of that type to that template. Here is a more complete …

Hi @Gary_Verhaegen I simply have a DAML templates, another DAML script file I built the dar file, uploaded to sandbox using daml start when i run my script, i get PS C:\Users\Admin\Rohit_TakeHomeAssignment\loan-project-medium> daml script --dar .daml/dist/loan-project-0.0.1.dar --script-name Tes…

Hi, again, @Rohit_Mittal and welcome to the forums! You’ll have better success getting a response to your questions if you create new posts for new questions. Posting to an existing question only gives visibility to those subscribed to the question.

Reading data from JSON file using DAML Script

App Development

Rohit_Mittal August 31, 2024, 7:47am 12

Can you please help @WallaceKelly

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Reading data from JSON file using DAML Script

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