Description

Adds new methods to Backend to support persisting and retrieving Graphs + GraphSnapshots and retrieving GraphSnapshots from a tag. This also changes a couple of the other Backend methods to accept a GraphSnapshot instance instead of a name, snapshot_id pair.

While working on this, I noticed that hash(graph) could change, even though the models are (intended to be) immutable. This turned out to be due to @cached_propertys, which are now ignored and fixed in 6626530.

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

Updated tests

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in upstream modules