From 4c394de70b61abade373acc496ce528dcab622e2 Mon Sep 17 00:00:00 2001
From: Jonas Platte <jonas@lumeo.com>
Date: Thu, 16 Jul 2020 16:59:11 +0200
Subject: [PATCH] Add SQLX_OFFLINE env variable to force metadata usage

---
 sqlx-cli/README.md           |  9 ++++++++-
 sqlx-macros/src/query/mod.rs | 16 ++++++++++++----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/sqlx-cli/README.md b/sqlx-cli/README.md
index 9318a3d0..e9916f42 100644
--- a/sqlx-cli/README.md
+++ b/sqlx-cli/README.md
@@ -51,7 +51,8 @@ $ sqlx migration run
 Compares the migration history of the running database against the `migrations/` folder and runs
 any scripts that are still pending.
 
-#### Enable building in "offline" mode with `query!()` 
+#### Enable building in "offline" mode with `query!()`
+
 Note: must be run as `cargo sqlx`.
 
 ```bash
@@ -74,3 +75,9 @@ cargo sqlx prepare --check
 ```
 Exits with a nonzero exit status if the data in `sqlx-data.json` is out of date with the current
 database schema and queries in the project. Intended for use in Continuous Integration.
+
+#### Force building in offline mode
+
+To make sure an accidentally-present `DATABASE_URL` environment variable or `.env` file does not
+result in `cargo build` (trying to) access the database, you can set the `SQLX_OFFLINE` environment
+variable.
diff --git a/sqlx-macros/src/query/mod.rs b/sqlx-macros/src/query/mod.rs
index e41ea998..04f2193b 100644
--- a/sqlx-macros/src/query/mod.rs
+++ b/sqlx-macros/src/query/mod.rs
@@ -35,11 +35,14 @@ pub fn expand_input(input: QueryMacroInput) -> crate::Result<TokenStream> {
     }
 
     // if `dotenv` wasn't initialized by the above we make sure to do it here
-    match dotenv::var("DATABASE_URL").ok() {
-        Some(db_url) => expand_from_db(input, &db_url),
+    match (
+        dotenv::var("SQLX_OFFLINE").is_ok(),
+        dotenv::var("DATABASE_URL"),
+    ) {
+        (false, Ok(db_url)) => expand_from_db(input, &db_url),
 
         #[cfg(feature = "offline")]
-        None => {
+        _ => {
             let data_file_path = std::path::Path::new(&manifest_dir).join("sqlx-data.json");
 
             if data_file_path.exists() {
@@ -54,7 +57,12 @@ pub fn expand_input(input: QueryMacroInput) -> crate::Result<TokenStream> {
         }
 
         #[cfg(not(feature = "offline"))]
-        None => Err("`DATABASE_URL` must be set to use query macros".into()),
+        (true, _) => {
+            Err("The cargo feature `offline` has to be enabled to use `SQLX_OFFLINE`".into())
+        }
+
+        #[cfg(not(feature = "offline"))]
+        (false, Err(_)) => Err("`DATABASE_URL` must be set to use query macros".into()),
     }
 }