Suggestion: don't modify parent when chaining db methods

[jlowin]

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This is just a suggestion, but as a new user I found it surprising that calling methods like child() actually modified the parent rather than returning a new object. This seems "unpythonic"; typically chained methods that return objects would leave the parent untouched.

For example:

db = firebase.database()
ref = db.child('key1').child('key2')
print(ref.path) # key1/key2, as expected
print(db.path) # key1/key2 -- unexpected! 

The reason this is surprising is that if I assume the parent is unmodified, I might try to reuse it:

ref2 = db.child('key3').child('key4')
print(db.path) # key1/key2/key3/key4 -- unexpected!
print(ref.path) # key1/key2/key3/key4 -- unexpected!
print(ref2.path) # key1/key2/key3/key4 -- unexpected!

Complicating matters further, is seems that calling set() or get() clears the path. So there is a hidden state being managed behind the scenes.

My suggestion is to leave the API just as it is, but instead of setting path on self when calling child(), create a copy of the database service, set the path on that copy, and return the copy.

[ashemah]

I keep getting bitten by this behaviour.

[jlowin]

Here is a worst-case scenario. With an admin service account (or poorly set permissions), this LOOKS like I'm just erasing two child nodes, but I'm actually erasing the entire database****

db = firebase.database()

ref1 = db.child(some_path)
ref2 = db.child(some_other_path)

ref1.set({})
ref2.set({})

[naure]

This is indeed broken at the moment. Coming from the official javascript library and lured by the identical method names, you're almost guaranteed to erase the entire database or get other surprising behaviors depending on the order of method calls.

The self.path of Database/Reference objects should never change.

[steliosrammos]

This is quite frustrating, is any work being done to fix it?