Caching conflict when creating CSV schemas with different views for the same POJO

[mrpiggi]

#195 added csv schema creation with views. Using the same CsvMapper with the same POJO for different views leads to unexpected results as the used view is not considered when a schema is loaded from cache as it was registered for the pojoType. Obviously, the used view should be part of the key for the cache maps _untypedSchemas and _typedSchemas.

jackson-dataformats-text/csv/src/main/java/com/fasterxml/jackson/dataformat/csv/CsvMapper.java

Lines 425 to 433 in 1202fec

	protected CsvSchema _schemaFor(JavaType pojoType, LRUMap<JavaType,CsvSchema> schemas,
	boolean typed, Class<?> view)
	{
	synchronized (schemas) {
	CsvSchema s = schemas.get(pojoType);
	if (s != null) {
	return s;
	}
	}

Edit: A workaround is quite simple. In order to clear the cache, just use csvmapper.copy().schemaForWithView(...) instead of csvmapper.schemaForWithView(...).

[cowtowncoder]

Oh. Yes indeed... Gnarly one, this. Wonder if this should initially (2.13?) simply avoid caching when there is active View, and then for 2.14 add proper caching with possible view.

[mrpiggi]

In my eyes, caching only when view==null would be a sufficient fix for 2.13

[cowtowncoder]

Fixed for upcoming 2.13.1 by simply skipping caching if view enabled. May be improved in future if someone has an itch; just need to change key for cache.

[mrpiggi]

What would be suitable to create a corresponding key from JavaType pojoType and Class<?> view for LRUMap? Is there already a generic tuple or something similar to the existing TypeKey integrated in jackson-core or jackson-databind that could be used for this purpose or would a new class (ViewKey?) be necessary?

[cowtowncoder]

I can't think of a type and since we cannot add 3rd party Pair or Tuple, would need a simple key class like ViewKey.
@mrpiggi if you have time and interest I'd be happy to help merge this to 2.14.

jackson-databind probably has some similar class already fwtw, for (de)serializer caching. Not with exact types but similar.

[mrpiggi]

Sure, I can try to find some time. Should I create a PR based on 2.13 or 2.14? Are there any contribution guide lines?

[cowtowncoder]

2.14: keeping caching simple for 2.13 patch just in case.

There isn't a lot about contributing, just this:

https://github.com/FasterXML/jackson/blob/master/CONTRIBUTING.md