Change parameters from String to &str

[ericapywang]

Problem

One of the parameters for fetch was &[String] instead of &[&str]. Similarly, one of the parameters for query_by_id was String instead of &str.

Solution

I changed the parameter types to &[&str] and &str respectively for consistency with other functions. I also updated all relevant code.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Infrastructure change (CI configs, etc)
• Non-code change (docs, etc)
• None of the above: (explain here)

Test Plan

Test cases should pass.