Add mode to IDBPTransaction

[zhouhanseng]

Fixes https://github.com/jakearchibald/idb/issues/140

1. Add type check for transaction's mode, it is impossible to pass a readonly transaction to a function that requires a readwrite transaction.

2. Exclude add(), put(), delete(), clear() from objectstore created by readonly transaction. Keep createIndex() only in objectstore created by versionchange transaction.

const schemaDB = await openDBWithSchema();
const db = schemaDB as IDBPDatabase<TestDBSchema>;

const t1 = db.transaction("store1", "readonly") 
const t2 = db.transaction("store1", "readwrite") 

const action = (t: IDBPTransaction<TestDBSchema, ['store1'], "readwrite">) => {
  t.store.clear()
}

// ts compiler: Type '"readonly"' is not assignable to type '"readwrite"'
action(t1)
// ts compiler: IDBPObjectStore<TestDBSchema, ["store1"], "store1", "readonly">.add: undefined
t1.store.add({name: 'm'})
// ts compiler: IDBPObjectStore<TestDBSchema, ["store1"], "store1", "readwrite">.createIndex: undefined
t2.store.createIndex('name', 'name')

[zhouhanseng]

Updated the test.

[zhouhanseng]

Updated the test.

[jakearchibald]

Excited about this. I'll review the change soon and get it merged. I guess this will be a new major version for safety.

[zhouhanseng]

Is this PR okay?

[jakearchibald]

I want to give it some detailed testing before I land it, but it looks good at a glance. I also need to figure out if it requires a major version bump or not. Sorry for the delay, just not got a bunch of free time right now. It's still on my todo list, and I really appreciate the work you've put in.

[jakearchibald]

Sorry I still haven't gotten to this. It's still on my TODO list, I've just hit a bunch of deadlines.

[jakearchibald]

Don't worry about the conflicts, I'll solve those

[jakearchibald]

@zhouhanseng I finally found time to review this. Excellent work. I'm going to pick up a couple of other bug reports and publish a new version.

[Jack-Works]

hi @zhouhanseng, can a ReadWrite tx assign to a ReadOnly tx? That is a safe action.

[Jack-Works]

Store names should also come in the check:

The type checking rule should be:

1. If A contains more IDB stores than B, B = A should pass, A = B should error
2. If A is RW and B is RO, B = A should pass, A = B should error

[zhouhanseng]

@Jack-Works No, it can't assign.

[Jack-Works]

@zhouhanseng it should be, it's runtime safe so it should pass the compiler.