Customize the macro error message based on the metadata

Author: Nemo157

sqlx-macros-core/src/query/mod.rs

@@ -160,34 +160,46 @@ pub fn expand_input<'a>(
             ..
         } => QueryDataSource::live(db_url)?,
 
-        _ => {
+        Metadata {
+            offline,
+            database_url,
+            ..
+        } => {
             // Try load the cached query metadata file.
             let filename = format!("query-{}.json", hash_string(&input.sql));
 
             // Check SQLX_OFFLINE_DIR, then local .sqlx, then workspace .sqlx.
-            let data_file_path = if let Some(sqlx_offline_dir_path) = env("SQLX_OFFLINE_DIR")
-                .ok()
-                .map(PathBuf::from)
+            let dirs = [
+                env("SQLX_OFFLINE_DIR").ok().map(PathBuf::from),
+                Some(METADATA.manifest_dir.join(".sqlx")),
+                Some(METADATA.workspace_root().join(".sqlx")),
+            ];
+            let Some(data_file_path) = dirs
+                .iter()
+                .filter_map(|path| path.as_ref())
                 .map(|path| path.join(&filename))
-                .filter(|path| path.exists())
-            {
-                sqlx_offline_dir_path
-            } else if let Some(local_path) =
-                Some(METADATA.manifest_dir.join(".sqlx").join(&filename))
-                    .filter(|path| path.exists())
-            {
-                local_path
-            } else if let Some(workspace_path) =
-                Some(METADATA.workspace_root().join(".sqlx").join(&filename))
-                    .filter(|path| path.exists())
-            {
-                workspace_path
-            } else {
-                return Err(
-                    "`DATABASE_URL` must be set, or `cargo sqlx prepare` must have been run \
-                     and .sqlx must exist, to use query macros"
-                        .into(),
-                );
+                .find(|path| path.exists())
+            else {
+                let any_dir_exists = dirs
+                    .iter()
+                    .filter_map(|path| path.as_ref())
+                    .any(|path| path.exists());
+                return Err([
+                    match (database_url, offline) {
+                        (None, false) => {
+                            "`DATABASE_URL` must be set to use query macros online, or "
+                        }
+                        (Some(_), true) => {
+                            "`SQLX_OFFLINE=true` must be disabled to use query macros online, or "
+                        }
+                        _ => "",
+                    },
+                    if any_dir_exists {
+                        "`cargo sqlx prepare` must be run to update the prepared files"
+                    } else {
+                        "`cargo sqlx prepare` must be run and .sqlx to exist to use query macros offline"
+                    },
+                ].join("").into());
             };
 
             QueryDataSource::Cached(DynQueryData::from_data_file(&data_file_path, &input.sql)?)