Missing property type in reversed `remove` op

[lukasschwab]

Description

This demo mentioned in README.md seems broken:

Compile back from an updated "simple issue" to a new github issue file:

cat ./demo/simple-issue.json | node ./dist/cli.js -l ./demo/github-arthropod.lens.yml -r -b ./demo/github-issue.json

In practice:

$ cat ./demo/simple-issue.json | node ./dist/cli.js -l ./demo/github-arthropod.lens.yml -r -b ./demo/github-issue.json
./dist/json-schema.js:35
        throw new Error(`Missing property name in addProperty.\nFound:\n${JSON.stringify(property)}`);
        ^

Error: Missing property name in addProperty.
Found:
{"op":"add","name":"labels"}
    at addProperty (./dist/json-schema.js:35:15)
    at applyLensOperation (./dist/json-schema.js:338:20)
    at ./cambria-project/dist/json-schema.js:366:16
    at Array.reduce (<anonymous>)
    at Object.updateSchema (./dist/json-schema.js:363:17)
    at Object.applyLensToDoc (./dist/doc.js:51:40)
    at Object.<anonymous> (./dist/cli.js:25:22)
    at Module._compile (internal/modules/cjs/loader.js:1085:14)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)
    at Module.load (internal/modules/cjs/loader.js:950:32)

Cause

github-arthropod.lens.yml defines a valid remove op––no type required:

cambria-project/demo/github-arthropod.lens.yml

Lines 41 to 42 in da89614

	- remove:
	name: labels

And reverse.ts just swaps in the add op:

cambria-project/src/reverse.ts

Lines 30 to 34 in da89614

	case 'remove':
	return {
	...lensOp,
	op: 'add',
	}

But an add op must specify a type! It's the type missing, not the name:

cambria-project/src/json-schema.ts

Lines 35 to 37 in da89614

	if (!name || !type) {
	throw new Error(`Missing property name in addProperty.\nFound:\n${JSON.stringify(property)}`)
	}

Solutions

• Require types on remove ops.
• Set an unrestrictive default type when reversing a remove op without a type. I sketched that out here, and confirmed the demo works as expected and unit tests pass: lukasschwab@77b602e
• Loosen the commitment to reversibility. This seems incompatible with the project goals.

Let me know if you'd like me to open a PR.

Cool stuff––enjoyed the HYTRADBOI talk!

[michielbdejong]

I ran into this same problem when trying to follow the readme instructions, and looks like lukasschwab@77b602e indeed makes this error disappear.