BigQuery Python Client v0.28.0: Can't recover {Dataset,Table}References from Dataset or Table objects

[robfraz]

Hello,

In v0.28.0 of the BigQuery Python Client, it doesn't seem possible to recover the original DatasetReference or TableReference used to create the the Dataset or Table, thus preventing any part of the API (or a user's application) that requires a reference to also take the Dataset or Table object. It seems the reference used in creating the Dataset or Table is lost on object creation [1][2].

For example, in the client.load_table_from_file() function [3], a table_ref is expected; it seems logically unreasonable that a full Table object can't be used to fulfil the need for a table reference.

Cheers,
Rob

[1] https://github.com/GoogleCloudPlatform/google-cloud-python/blob/0.28.0/bigquery/google/cloud/bigquery/table.py#L170-L177
[2] https://github.com/GoogleCloudPlatform/google-cloud-python/blob/0.28.0/bigquery/google/cloud/bigquery/dataset.py#L204-L208
[3] https://github.com/GoogleCloudPlatform/google-cloud-python/blob/0.28.0/bigquery/google/cloud/bigquery/client.py#L692-L706

[dhermes]

@tswast Can you lend a hand here?

[tswast]

This is a good feature request. I agree that such a change would improve usability.

I see two ways to address this:

1. To allow either Table or TableReference for operations such as client.load_table_from_file(). Likewise for Dataset and DatasetReference.
2. Add a helper method to get the TableReference from a Table object. Likewise for Dataset and DatasetReference.

In the meantime, the workaround is to create a TableReference manually from a Table.

dataset_ref = DatasetReference(table.project, table.dataset_id)
table_ref = TableReference(dataset_ref, table.table_id)

My preference would be for (2). Something like the following code:

table_ref = table.reference

[robfraz]

@tswast Sounds good. You want me to submit a pull request, or is this something that you'll add yourselves?

[tswast]

Contributions welcome. :-)

[tswast]

I've got a PR pending #4405

[robfraz]

Nice - thanks. I wouldn't have had a chance to get to it until the weekend just gone, and you beat me to it.