JSON bug

[jwillmer]

Problem:

• Converting input to a JS object in JS activity and returning it
• Using the output of the JS activity in a HTTP activity to send it as JSON
• Sent request does not contain the right JSON.

JS activity called process

const raw = activities.webhook.Output().RawBody;
const body = JSON.parse(raw);
const items = body.Event.Control.Items;
let output = [];

for (const item of items) {
    for (const value of item.Values) {
        output.push({
            Item: item.Id,
            Values: {
                ListItem: value.Title,
                Value: value.Value
            }
        });
    }
}

return output;

Transfered data between the steps:

[
 {
  "Item": "e991f17a-246b-4d7d-a4b6-abbf54bd6911",
  "Values": {
   "ListItem": "Name",
   "Value": "Test"
  }
 },
 {
  "Item": "e991f17a-246b-4d7d-a4b6-abbf54bd6911",
  "Values": {
   "ListItem": "E-mail",
   "Value": "test@test.com"
  }
 }
}

POST content (generation) of the HTTP activity

return JSON.stringify(activities.process.Output());

Received data at my endpoint

[
  {
    "Item": "e991f17a-246b-4d7d-a4b6-abbf54bd6911",
    "Values": {
      "Count": 2,
      "IsReadOnly": true
    }
  },
  {
    "Item": "e991f17a-246b-4d7d-a4b6-abbf54bd6911",
    "Values": {
      "Count": 2,
      "IsReadOnly": true
    }
  }
]

Note: Stringifying the JS object in the JS activity and then just using it in the HTTP activity (return activities.process.Output();) returns the correct JSON.

[sfmskywalker]

I can reproduce with the following (simplified) workflow:

JSON version of the workflow for testing:
js-serialization-workflow.zip

The issue lies with the serialization of the JavaScript object returned from the RunJavaScript activity.
Looking into that next.

[sfmskywalker]

The problem is not the output of the first activity (which is an array of ExpandoObjects), but with json.Stringify being unable to properly stringify the list of expandos to JSON.

[sfmskywalker]

Interestingly enough, Newtonsoft Json can properly serialize the expandos to JSON. Sample result:

[
{
   "Item": "e991f17a-246b-4d7d-a4b6-abbf54bd6911",
   "Values": {
      "ListItem": "Name",
      "Value": "Test"
    }
  },
  {
    "Item": "e991f17a-246b-4d7d-a4b6-abbf54bd6911",
    "Values": {
      "ListItem": "E-mail",
      "Value": "test@test.com"
    }
  }
]

What I suggest we do is add a custom serialization JS function that we use instead of JSON.stringify *which is provided by Jint, so maybe not a good idea to try and replace it).

[sfmskywalker]

The following JS expression can now be used:

return jsonEncode(activities.process.Output());

The result will look like this:

[{"Item":"e991f17a-246b-4d7d-a4b6-abbf54bd6911","Values":{"ListItem":"Name","Value":"Test"}},{"Item":"e991f17a-246b-4d7d-a4b6-abbf54bd6911","Values":{"ListItem":"E-mail","Value":"test@test.com"}}]

[jwillmer]

It works but with this solution you might want to interfere with JSON.stringify and automatically use your function (in the backend) when a user write this. Since it is not obvious that JSON is supported but stringify is broken.

[sfmskywalker]

Yeah maybe. But, barring whether it's even possible or not, I don't know that JSON stringify is actually broken. For all I know it's expected behavior when serializing ExpandoObject. And if we replace it, we may inadvertently break some standard protocol implemented by it.

Would be good if someone could do a little investigation and look at Jint's JSON stringify implementation.

[jwillmer]

Tracking upstream: sebastienros/jint#995

[sfmskywalker]

The ExpandoObject serialization issue was fixed in sebastienros/jint#996.