factor url parameter setting code

Author: lovasoa

src/webserver/database/sqlpage_functions/functions.rs

@@ -377,11 +377,7 @@ async fn link<'a>(
         let encoded = serde_json::from_str::<URLParameters>(&parameters).with_context(|| {
             format!("link: invalid URL parameters: not a valid json object:\n{parameters}")
         })?;
-        let encoded_str = encoded.get();
-        if !encoded_str.is_empty() {
-            url.push('?');
-            url.push_str(encoded_str);
-        }
+        encoded.append_to_url(&mut url);
     }
     if let Some(hash) = hash {
         url.push('#');
@@ -632,11 +628,7 @@ async fn set_variable<'a>(
     }
 
     let mut url = context.path.clone();
-    let encoded_str = params.get();
-    if !encoded_str.is_empty() {
-        url.push('?');
-        url.push_str(encoded_str);
-    }
+    params.append_to_url(&mut url);
 
     Ok(url)
 }

src/webserver/database/sqlpage_functions/url_parameter_deserializer.rs

@@ -68,8 +68,11 @@ impl URLParameters {
         }
     }
 
-    pub fn get(&self) -> &str {
-        &self.0
+    pub fn append_to_url(&self, url: &mut String) {
+        if !self.0.is_empty() {
+            url.push('?');
+            url.push_str(&self.0);
+        }
     }
 }
 
@@ -107,6 +110,12 @@ impl<'de> Deserialize<'de> for URLParameters {
     }
 }
 
+impl std::fmt::Display for URLParameters {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
 #[test]
 fn test_url_parameters_deserializer() {
     use serde_json::json;
@@ -166,12 +175,12 @@ fn test_url_parameters_deserializer_issue_879() {
 fn test_push_single_or_vec() {
     let mut params = URLParameters(String::new());
     params.push_single_or_vec("k", SingleOrVec::Single("v".to_string()));
-    assert_eq!(params.get(), "k=v");
+    assert_eq!(params.to_string(), "k=v");
 
     let mut params = URLParameters(String::new());
     params.push_single_or_vec(
         "arr",
         SingleOrVec::Vec(vec!["a".to_string(), "b".to_string()]),
     );
-    assert_eq!(params.get(), "arr[]=a&arr[]=b");
+    assert_eq!(params.to_string(), "arr[]=a&arr[]=b");
 }