feat: multi-tenant example

No longer Axum-based because filling out the request routes would have distracted from the purpose of the example.

Author: abonander

Cargo.lock

@@ -11,7 +11,7 @@ members = [
     "sqlx-postgres",
     "sqlx-sqlite",
     "examples/mysql/todos",
-    "examples/postgres/axum-multi-tenant",
+    "examples/postgres/multi-tenant",
     "examples/postgres/axum-social-with-tests",
     "examples/postgres/chat",
     "examples/postgres/files",

Cargo.toml

@@ -16,13 +16,15 @@ tokio = { version = "1", features = ["rt-multi-thread", "macros"] }
 
 sqlx = { path = "../../..", version = "0.8.3", features = ["runtime-tokio", "postgres"] }
 
-axum = "0.8.1"
+axum = { version = "0.8.1", features = ["macros"] }
 
-clap = { version = "4.5.30", features = ["derive", "env"] }
 color-eyre = "0.6.3"
 dotenvy = "0.15.7"
 tracing-subscriber = "0.3.19"
 
+rust_decimal = "1.36.0"
+
+rand = "0.8.5"
 
 [lints]
 workspace = true

examples/postgres/axum-multi-tenant/payments/src/lib.rs

@@ -5,6 +5,8 @@ with their own set of migrations.
 
 * The main crate, an Axum app.
     * Owns the `public` schema (tables are referenced unqualified).
+    * Migrations are moved to `src/migrations` using config key `migrate.migrations-dir`
+      to visually separate them from the subcrate folders.
 * `accounts`: a subcrate simulating a reusable account-management crate.
     * Owns schema `accounts`.
 * `payments`: a subcrate simulating a wrapper for a payments API.
@@ -20,3 +22,27 @@ prefixes, but this can cause some really confusing issues when names conflict.
 This example will generate a `_sqlx_migrations` table in three different schemas, and if `search_path` is set
 to `public,accounts,payments` and the migrator for the main application attempts to reference the table unqualified,
 it would throw an error.
+
+# Setup
+
+This example requires running three different sets of migrations.
+
+Ensure `sqlx-cli` is installed with Postgres support.
+
+Start a Postgres server.
+
+Create `.env` with `DATABASE_URL` or set it in your shell environment.
+
+Run the following commands:
+
+```
+(cd accounts && sqlx db setup)
+(cd payments && sqlx migrate run)
+sqlx migrate run
+```
+
+It is an open question how to make this more convenient; `sqlx-cli` could gain a `--recursive` flag that checks
+subdirectories for `sqlx.toml` files, but that would only work for crates within the same workspace. If the `accounts`
+and `payments` crates were instead crates.io dependencies, we would need Cargo's help to resolve that information.
+
+An issue has been opened for discussion: <https://github.com/launchbadge/sqlx/issues/3761>

examples/postgres/axum-multi-tenant/src/http/mod.rs

@@ -10,11 +10,13 @@ tokio = { version = "1", features = ["rt", "sync"] }
 argon2 = { version = "0.5.3", features = ["password-hash"] }
 password-hash = { version = "0.5", features = ["std"] }
 
-uuid = "1"
+uuid = { version = "1", features = ["serde"] }
 thiserror = "1"
 rand = "0.8"
 
-time = "0.3.37"
+time = { version = "0.3.37", features = ["serde"] }
+
+serde = { version = "1.0.218", features = ["derive"] }
 
 [dev-dependencies]
 sqlx = { workspace = true, features = ["runtime-tokio"] }

examples/postgres/axum-multi-tenant/src/main.rs

@@ -12,15 +12,15 @@ create or replace function accounts.set_updated_at()
 $$
 begin
     NEW.updated_at = now();
-return NEW;
+    return NEW;
 end;
 $$ language plpgsql;
 
 create or replace function accounts.trigger_updated_at(tablename regclass)
     returns void as
 $$
 begin
-execute format('CREATE TRIGGER set_updated_at
+    execute format('CREATE TRIGGER set_updated_at
         BEFORE UPDATE
         ON %s
         FOR EACH ROW