add queryhelp property to QueryBuilder

[ltalirz]

fix #3522

• add queryhelp property to QueryBuilder
  (currently pipes through to get_json_compatible_queryhelp)
• add deepcopy function to allow direct copies of QueryBuilder
  instances
• test that QueryBuilder can be re-created from queryhelp
• remove test_query.py and merge with orm/test_querybuilder.py

[ltalirz]

The test I added is here: https://github.com/aiidateam/aiida-core/pull/3524/files#diff-b9a67a0878b5bdee86b7a596950bc95fR678

[sphuber]

signature should be def __deepcopy__(self, memo)

[ltalirz]

fixed!

[sphuber]

no need for intermediate variable assignment

[ltalirz]

I had it in here as a bit of a help that what is being returned here is actually a querybuilder.
debatable though whether this is helpful - I'll get rid of it

[sphuber]

Why only __deepcopy__ implementation. Wouldn't a normal copy also not work? Since the queryhelp won't contain any references to other objects a shallow copy would also just work when implemented like this no?

[ltalirz]

Well, I chose this because the implementation of the queryhelp uses deepcopy.

aiida-core/aiida/orm/querybuilder.py

Lines 1760 to 1767 in 5a1f18b

	return copy.deepcopy({
	'path': self._path,
	'filters': self._filters,
	'project': self._projections,
	'order_by': self._order_by,
	'limit': self._limit,
	'offset': self._offset,
	})

And the deepcopy is actually necessary since it contains nested dictionaries:

In [1]: qb=QueryBuilder()

In [2]: qb.append(Data)
Out[2]: <aiida.orm.querybuilder.QueryBuilder at 0x11ea02208>

In [3]: qb.queryhelp
Out[3]:
{'path': [{'entity_type': 'data.Data.',
   'tag': 'Data_1',
   'joining_keyword': None,
   'joining_value': None,
   'outerjoin': False,
   'edge_tag': None}],
 'filters': {'Data_1': {'node_type': {'like': 'data.%'}}},
 'project': {'Data_1': []},
 'order_by': {},
 'limit': None,
 'offset': None}

[sphuber]

Thanks @ltalirz just some minor comments

[sphuber]

Thanks leo