How to use sqlx::migrate! in a nested child?

[kumawatdarshan]

my workspace at root level: [migrations, crates]

the file where I am using migrate! is in crates/x/y/z/xyz.rs, in a similar scenario, I got away with CARGO_WORKSPACE_DIR but what can be done in sqlx case?

doing ../../../../migrations gives me error canonicalizing migration directory ..... no such file or directory.

[Felipe01001]

migrate!() does not resolve the path relative to the Rust source file. It resolves it relative to the package root — the directory containing the Cargo.toml for the crate that invokes the macro.

For example, with this layout:

workspace/
├── migrations/
└── crates/
    └── x/
        ├── Cargo.toml
        └── src/y/z/xyz.rs

the invocation in xyz.rs should be:

static MIGRATOR: sqlx::migrate::Migrator =
    sqlx::migrate!("../../migrations");

The two .. components are counted from crates/x/Cargo.toml, regardless of how deeply nested xyz.rs is. Using ../../../../migrations in this example walks too far because it is being calculated as though the starting point were the source file.

The macro expects a string literal, so interpolating CARGO_WORKSPACE_DIR is not the intended mechanism. If several workspace crates need the same migrations, a clean arrangement is to declare the Migrator once in a shared database crate and re-export it.

One related detail: on stable Rust, add a build.rs to the crate containing the macro if newly added migration files are not triggering recompilation:

fn main() {
    println!("cargo:rerun-if-changed=../../migrations");
}

This path behavior is documented in sqlx::migrate!: the directory is relative to the project root containing Cargo.toml, unlike include_str!().