diesel setup will fail SQLite database creation if parent directories are not present

[sexnine]

Setup

Versions

• Rust: N/A
• Diesel: CLI version 2.2.10
• Database: SQLite
• Operating System Windows 11

Feature Flags

• diesel: N/A

Problem Description

diesel setup when using a local SQLite database will fail when parent directories to the file path are not present. The error message is vague and unexpected.

What are you trying to accomplish?

Creating a SQLite database.

What is the expected output?

Either:

• The directories should be created and then successfully create the database file
• Output a clear error message that says the directories aren't present and need to be created first prior to creating the database file

What is the actual output?

Creating database: data/db.db
Could not connect to database via `data/db.db`: Unable to open the database file

Are you seeing any additional errors?

Steps to reproduce

• Install diesel_cli
• Create an env file with:

  DATABASE_URL=data/db.db
  

• Run diesel setup... error
• mkdir data
• Run diesel setup... success

Checklist

• I have already looked over the issue tracker and the discussion forum for similar possible closed issues.

• This issue can be reproduced on Rust's stable channel. (Your issue will be
  closed if this is not the case)
• This issue can be reproduced without requiring a third party crate

[weiznich]

I converted this to a discussion as that's strictly speaking not a bug in diesel.

Diesel just passes a "opaque" database URL to the underlying database implementation. In this case that's SQLite. This means it's problematic for us to implement either of your "proposed" solutions:

The directories should be created and then successfully create the database file

That would require reimplementing sqlite's url parsing logic to differentiate between path and non-path URL's. See their documentation to understand what's all possible to be passed there.

Output a clear error message that says the directories aren't present and need to be created first prior to creating the database file

As this error message is generated by sqlite and not by diesel there is no maintainable way for diesel to change the error message. Such a change needs to be implemented in sqlite itself. Feel free to raise the issue there.