use indexmap to fix iteration order

Author: imor

Cargo.lock

@@ -25,6 +25,7 @@ uuid = "1"
 base64 = "0.13"
 lazy_static = "1"
 bimap = { version = "0.6.3", features = ["serde"] }
+indexmap = "2.2"
 
 [dev-dependencies]
 pgrx-tests = "=0.11.2"

Cargo.toml

@@ -1,14 +1,13 @@
-use std::collections::HashMap;
-
 use graphql_parser::query::{Field, Text};
+use indexmap::IndexMap;
 
 use crate::parser_util::alias_or_name;
 
 pub fn merge<'a, 'b, T>(fields: &[Field<'a, T>]) -> Result<Vec<Field<'a, T>>, String>
 where
     T: Text<'a> + Eq + AsRef<str> + Clone,
 {
-    let mut merged: HashMap<String, Field<'a, T>> = HashMap::new();
+    let mut merged: IndexMap<String, Field<'a, T>> = IndexMap::new();
 
     for current_field in fields {
         let response_key = alias_or_name(current_field);