Understanding Connector Package Methods • connector.databricks

Introduction

This vignette provides best practices for users and developers on what is returned by each method in connector packages. Understanding these methods and their return values is crucial for both users of connector packages and developers who want to create their own connector packages.

We tailored this guide for connector.databricks, but the same thing applies for all connector types of packages. You can have a look at original article here.

Why This Vignette?

We realized it might be confusing for users to understand which method returns which value. This vignette explains what each method does and provides an overview of general rules for both ConnectorDatabricksVolume and ConnectorDatabricksTable objects.

Apart from this vignette, we have made vignette explaining mechanisms behind some of the functions. More info can be find vignette("articles/read_write")

Methods and Return Values

Below is a table summarizing the methods and their return values:

Method	Return Value
`read_cnt()`	Content of the file
`write_cnt()`	`Connector` object
`list_content_cnt()`	Vector of items
`remove_cnt()`	`Connector` object
`download_cnt()`	`Connector` object
`upload_cnt()`	`Connector` object
`create_directory_cnt()`	`Connector` object, if `open = TRUE`, then new `Connector` object
`remove_directory_cnt()`	`Connector` object
`upload_directory_cnt()`	`Connector` object, if `open = TRUE`, then new `Connector` object
`download_directory_cnt()`	`Connector` object
`tbl_cnt()`	Content of the table. Either `dplyr::tbl()` or from `read_cnt()`

Detailed Explanations

`read_cnt()`

Reads the content of a file and returns it directly. This allows users to immediately work with the data without additional steps.

`write_cnt()`

After writing content to the Connector, this method returns the Connector object. This enables method chaining and provides confirmation that the write operation was successful.

`list_content_cnt()`

Returns a character vector of items (files/directories) in the current Connector allowing users to explore the content structure.

`remove_cnt()`

After removing a file or item, this method returns the Connector object, allowing for further operations and confirming the removal was successful.

`download_cnt()`

This method returns the Connector object after a download operation to allow for method chaining.

`upload_cnt()`

Similar to download_cnt(), this returns the Connector object after an upload, allowing for method chaining.

`create_directory_cnt()`

This method returns the Connector object. If the open parameter is set to TRUE, it returns a new Connector object pointing to the newly created directory.

`remove_directory_cnt()`

After removing a directory, this method returns the Connector object, allowing for further operations and confirming the removal was successful.

`upload_directory_cnt()`

Returns the current Connector object or a new one if the directory was opened (open = TRUE), allowing for immediate use of the uploaded directory.

`download_directory_cnt()`

Returns the Connector object to allow for method chaining.

`tbl_cnt()`

This method returns the content of a file in a tabular format. For file-based connectors, it typically uses read_cnt() to get the content. For database connections (DBI), it returns a dplyr::tbl() representation of the data.

Conclusion

Understanding these return values is crucial for effectively using and developing connector packages. By maintaining consistency in what each method returns, we ensure that different connector packages can be used interchangeably, promoting code reusability and a smoother user experience.

For developers creating new connector packages, adhering to these return value conventions will help maintain compatibility with existing tools and workflows that expect certain return types from these methods.