replace transports: Option<Vec<Transport>> with just Vec<Transport> (#999)

with a few serde directive we can get the same behaviour we had with
Option<Vec<Transport>> but only using Vec<Transport>

No need to change protocol specification

crates/cashu/src/nuts/nut18/payment_request.rs

@@ -3,7 +3,6 @@
 //! <https://github.com/cashubtc/nuts/blob/main/18.md>
 
 use std::fmt;
-use std::ops::Not;
 use std::str::FromStr;
 
 use bitcoin::base64::engine::{general_purpose, GeneralPurpose};
@@ -40,8 +39,8 @@ pub struct PaymentRequest {
     pub description: Option<String>,
     /// Transport
     #[serde(rename = "t")]
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub transports: Option<Vec<Transport>>,
+    #[serde(skip_serializing_if = "Vec::is_empty", default = "Vec::default")]
+    pub transports: Vec<Transport>,
     /// Nut10
     #[serde(skip_serializing_if = "Option::is_none")]
     pub nut10: Option<Nut10SecretRequest>,
@@ -168,8 +167,6 @@ impl PaymentRequestBuilder {
 
     /// Build the PaymentRequest
     pub fn build(self) -> PaymentRequest {
-        let transports = self.transports.is_empty().not().then_some(self.transports);
-
         PaymentRequest {
             payment_id: self.payment_id,
             amount: self.amount,
@@ -177,7 +174,7 @@ impl PaymentRequestBuilder {
             single_use: self.single_use,
             mints: self.mints,
             description: self.description,
-            transports,
+            transports: self.transports,
             nut10: self.nut10,
         }
     }
@@ -224,8 +221,7 @@ mod tests {
         );
         assert_eq!(req.unit.unwrap(), CurrencyUnit::Sat);
 
-        let transport = req.transports.unwrap();
-        let transport = transport.first().unwrap();
+        let transport = req.transports.first().unwrap();
 
         let expected_transport = Transport {_type: TransportType::Nostr, target: "nprofile1qy28wumn8ghj7un9d3shjtnyv9kh2uewd9hsz9mhwden5te0wfjkccte9curxven9eehqctrv5hszrthwden5te0dehhxtnvdakqqgydaqy7curk439ykptkysv7udhdhu68sucm295akqefdehkf0d495cwunl5".to_string(), tags: Some(vec![vec!["n".to_string(), "17".to_string()]])};
 
@@ -245,7 +241,7 @@ mod tests {
                 .parse()
                 .expect("valid mint url")]),
             description: None,
-            transports: Some(vec![transport.clone()]),
+            transports: vec![transport.clone()],
             nut10: None,
         };
 
@@ -262,8 +258,7 @@ mod tests {
         );
         assert_eq!(req.unit.unwrap(), CurrencyUnit::Sat);
 
-        let t = req.transports.unwrap();
-        let t = t.first().unwrap();
+        let t = req.transports.first().unwrap();
         assert_eq!(&transport, t);
     }
 
@@ -293,8 +288,7 @@ mod tests {
         assert_eq!(request.unit.clone().unwrap(), CurrencyUnit::Sat);
         assert_eq!(request.mints.clone().unwrap(), vec![mint_url]);
 
-        let t = request.transports.clone().unwrap();
-        let t = t.first().unwrap();
+        let t = request.transports.first().clone().unwrap();
         assert_eq!(&transport, t);
 
         // Test serialization and deserialization
@@ -497,8 +491,7 @@ mod tests {
             vec![MintUrl::from_str("https://8333.space:3338").unwrap()]
         );
 
-        let transport = payment_request.transports.as_ref().unwrap();
-        let transport = transport.first().unwrap();
+        let transport = payment_request.transports.first().unwrap();
         assert_eq!(transport._type, TransportType::Nostr);
         assert_eq!(transport.target, "nprofile1qy28wumn8ghj7un9d3shjtnyv9kh2uewd9hsz9mhwden5te0wfjkccte9curxven9eehqctrv5hszrthwden5te0dehhxtnvdakqqgydaqy7curk439ykptkysv7udhdhu68sucm295akqefdehkf0d495cwunl5");
         assert_eq!(
@@ -562,8 +555,7 @@ mod tests {
             ]
         );
 
-        let transport = payment_request_cloned.transports.unwrap();
-        let transport = transport.first().unwrap();
+        let transport = payment_request_cloned.transports.first().unwrap();
         assert_eq!(transport._type, TransportType::Nostr);
         assert_eq!(
             transport.target,
@@ -614,7 +606,7 @@ mod tests {
             payment_request_cloned.mints.unwrap(),
             vec![MintUrl::from_str("https://mint.example.com").unwrap()]
         );
-        assert_eq!(payment_request_cloned.transports, None);
+        assert_eq!(payment_request_cloned.transports, vec![]);
 
         // Test round-trip serialization
         let encoded = payment_request.to_string();

crates/cdk-cli/src/sub_commands/create_request.rs

@@ -100,7 +100,7 @@ pub async fn create_request(
             // We'll need the Nostr keys and relays later for listening
             let transport_info = Some((keys, relays, nprofile.public_key));
 
-            (Some(vec![nostr_transport]), transport_info)
+            (vec![nostr_transport], transport_info)
         }
         "http" => {
             if let Some(url) = &sub_command_args.http_url {
@@ -110,18 +110,18 @@ pub async fn create_request(
                     tags: None,
                 };
 
-                (Some(vec![http_transport]), None)
+                (vec![http_transport], None)
             } else {
                 println!(
                     "Warning: HTTP transport selected but no URL provided, skipping transport"
                 );
-                (None, None)
+                (vec![], None)
             }
         }
-        "none" => (None, None),
+        "none" => (vec![], None),
         _ => {
             println!("Warning: Unknown transport type '{transport_type}', defaulting to none");
-            (None, None)
+            (vec![], None)
         }
     };
 
@@ -234,7 +234,7 @@ pub async fn create_request(
     let nut10 = spending_conditions.map(Nut10SecretRequest::from);
 
     // Extract the transports option from our match result
-    let (transports_option, nostr_info) = transports;
+    let (transports, nostr_info) = transports;
 
     let req = PaymentRequest {
         payment_id: None,
@@ -243,7 +243,7 @@ pub async fn create_request(
         single_use: Some(true),
         mints: Some(mints),
         description: sub_command_args.description.clone(),
-        transports: transports_option,
+        transports,
         nut10,
     };
 

crates/cdk-cli/src/sub_commands/pay_request.rs

@@ -67,10 +67,10 @@ pub async fn pay_request(
 
     let matching_wallet = matching_wallets.first().unwrap();
 
-    let transports = payment_request
-        .transports
-        .clone()
-        .ok_or(anyhow!("Cannot pay request without transport"))?;
+    if payment_request.transports.is_empty() {
+        return Err(anyhow!("Cannot pay request without transport"));
+    }
+    let transports = payment_request.transports.clone();
 
     // We prefer nostr transport if it is available to hide ip.
     let transport = transports