Problem with Pipeline Parameter in Mapper Snap

[jhagist]

I am using a mapper snap to extract data from a json schema. This is the code from the expression

{id:$id}.extend($.fieldValues.map (elem => [elem.id, elem.type, elem.value]))

What I want to do is place this in a pipeline parameter (so can change this equation from the config file).

I can’t figure out the expression syntax. Here is a screenshot of my latest failure. 🙁

[brianrandolph]

Have you tried putting it in an expression library and then reference it there?

For example, I have an expression library file invItems.expr:
{
INVOICE_TARGET_DATE: _invoice_date || Date.now().toLocaleDateString(‘{"timeZone":"EST", “format”:“yyyy-MM-01”}’)
}

and then i reference that in the pipeline:

lib.invItems.INVOICE_TARGET_DATE

[tstack]

jhagist:

What I want to do is place this in a pipeline parameter (so can change this equation from the config file).

As you found out later, the value of a pipeline parameters is a string. In order to evaluate it, you’ll need to use the ‘eval()’ function, like so:

eval(_field1)

Alternatively, you can put the expression in a file and import that file as a library (see Expression Library). Your library file would contain an object with a field that contains your function, like so:

{
    extract: doc => {id:id}.extend(doc.fieldValues.map (elem => [elem.id, elem.type, elem.value]))
}

You can then execute that function in your mapper with an expression like this:

lib.mylib.extract($)

[jhagist]

Awesome that worked!

tstack:

eval(_field1)

I did not try the library but it is an interesting concept.

Personal note for anyone else struggling with this. I am would suggest using the library suggestion or a parameter for the entire function. I spent a ton of time trying to variablize out the function and this path is much easier.

Another point. You can’t use a variable with the json schemas in a mapper, it has to be a parameter.

Hope this helps! 😀