Add database and location query functionality

src/resolvers.rs

@@ -4,22 +4,55 @@ use sqlx::PgPool;
 
 pub struct QueryRoot;
 
+fn get_pg_pool<'a>(ctx: &'a Context<'_>) -> &'a PgPool {
+    ctx.data::<PgPool>()
+        .expect("A database connection does not exist")
+}
+
 #[Object]
 impl QueryRoot {
     pub async fn datasets(&self, ctx: &Context<'_>) -> anyhow::Result<Vec<Dataset>> {
-        let pool = ctx
-            .data::<PgPool>()
-            .expect("A database connection does not exist");
+        let pool = get_pg_pool(ctx);
 
         let rows: Vec<DatasetRow> = sqlx::query_as("SELECT * FROM datasets")
             .fetch_all(pool)
             .await?;
 
-        let result = rows.into_iter().map(|r| Dataset::from(r)).collect();
-        return Ok(result);
+        return Ok(rows.into_iter().map(|r| Dataset::from(r)).collect());
     }
 
-    async fn query_dataset(&self, id: i32) -> anyhow::Result<Record> {
-        unimplemented!("This doesn't work yet");
+    pub async fn query_dataset(
+        &self,
+        ctx: &Context<'_>,
+        id: i32,
+    ) -> anyhow::Result<Option<Record>> {
+        let pool = get_pg_pool(ctx);
+
+        let row: Option<RecordRow> = sqlx::query_as(
+            r#"SELECT * FROM records
+            WHERE dataset_id = $1
+            ORDER BY timestamp DESC
+            LIMIT 1;"#,
+        )
+        .bind(id)
+        .fetch_optional(pool)
+        .await?;
+
+        Ok(row.map(Into::into))
+    }
+
+    pub async fn get_location(&self, ctx: &Context<'_>, id: i32) -> anyhow::Result<Location> {
+        let pool = get_pg_pool(ctx);
+
+        let row: LocationRow = sqlx::query_as(
+            r#"SELECT * FROM locations
+            WHERE id = $1
+            LIMIT 1;"#,
+        )
+        .bind(id)
+        .fetch_one(pool)
+        .await?;
+
+        Ok(row.into())
     }
 }