Fix array formatting for SQL

src/graphql.rs

@@ -79,21 +79,24 @@ where
 }
 
 #[inline]
-fn format_array_for_sql<T>(values: &[T]) -> String
+fn format_array_for_sql<I, T>(values: I) -> String
 where
-    T: Display
+    I: IntoIterator<Item=T>,
+    T: Display,
 {
-    match values.len() {
-        1.. => {
-            let mut output = values[0].to_string();
-            for v in &values[1..] {
+    let mut iter = values.into_iter();
+
+    let mut output = match iter.next() {
+        Some(first) => first.to_string(),
+        None => return String::new(),
+    };
+
+    for v in iter {
         output += ",";
         output += &v.to_string();
     }
+
     output
-        },
-        _ => values.first().map(|v| v.to_string()).unwrap_or(String::new()),
-    }
 }
 
 #[inline]