Fix get columns in relation #197
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Specifically, it fails when it's called on a model that was created in the same run. At the start of the run, the cache is populated, setting Relation.information to be the string output of a DESCRIBE EXTENDED query, which allows columns and metadata to be parsed. However, when models are created, a Relation with information=None is saved in the cache (since columns and metadata aren't returned from a CREATE TABLE / VIEW statement). This means that an `expected string or bytes-like object` error is raised when attempting to regex-parse None.
If the `information` attribute is not yet set, we fall back on the non-cached version to find column information. We could _also_ cache the output of that query, but given that it wasn't cached originally, I leave it as it is.
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* Add test for failing get_columns_in_relation Specifically, it fails when it's called on a model that was created in the same run. At the start of the run, the cache is populated, setting Relation.information to be the string output of a DESCRIBE EXTENDED query, which allows columns and metadata to be parsed. However, when models are created, a Relation with information=None is saved in the cache (since columns and metadata aren't returned from a CREATE TABLE / VIEW statement). This means that an `expected string or bytes-like object` error is raised when attempting to regex-parse None. * Only parse cols from cache if there's information If the `information` attribute is not yet set, we fall back on the non-cached version to find column information. We could _also_ cache the output of that query, but given that it wasn't cached originally, I leave it as it is. * Add get_columns_in_relation fix to CHANGELOG
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resolves #196 / this slack thread
Description
get_columns_in_relationfails when it's called on a model that was created in the same run.At the start of the run, the cache is populated, setting Relation.information to be the string output of a DESCRIBE EXTENDED query, which allows columns and metadata to be parsed.
However, when models are created, a Relation with information=None is saved in the cache (since columns and metadata aren't returned from a CREATE TABLE / VIEW statement). This means that an
expected string or bytes-like objecterror is raised when attempting to regex-parse None.This change updates
get_columns_in_relationto fall back to actually querying the schema when the information attribute isn't set for a relation (in addition to the current behaviour which falls back if a relation isn't in the cache at all)Checklist
CHANGELOG.mdand added information about my change to the "dbt next" section.