Added nft pagination

candid/nft.did

@@ -40,5 +40,7 @@ service : {
 
     // Canister ethods    
     "get_all"      : () -> (vec nft_canister) query;
+    "get_all_paginated"        :  (offset: opt nat64, limit: opt nat64) -> (variant { Ok: vec nft_canister; Err: operation_error });
+
     "add_admin"    : (principal) -> (operation_response);
 }

registries/nft/src/common_types.rs

@@ -28,6 +28,12 @@ pub struct NftCanister {
     pub details: Vec<(String, DetailValue)>,
 }
 
+#[derive(CandidType, Clone, Debug, PartialEq)]
+pub struct GetAllPaginatedResponse {
+    pub amount: usize,
+    pub nfts: Vec<&'static NftCanister>,
+}
+
 #[derive(CandidType, Debug, PartialEq, Deserialize, Clone)]
 pub enum OperationError {
     NotAuthorized,
@@ -43,3 +49,4 @@ pub enum RegistryResponse {
 }
 
 pub const CANISTER_REGISTRY_ID: &'static str = "curr3-vaaaa-aaaah-abbdq-cai";
+pub const DEFAULT_LIMIT: usize = 20;

registries/nft/src/nft.rs

@@ -46,6 +46,27 @@ impl Registry {
     pub fn get_all(&self) -> Vec<&NftCanister> {
         self.0.values().collect()
     }
+
+    pub fn get_all_paginated(&self, offset: usize, _limit: usize) -> Result<Vec<&NftCanister>, OperationError> {
+
+        let nfts: Vec<&NftCanister> = self.0.values().collect();
+
+        if offset > nfts.len() {
+            return Err(OperationError::BadParameters);
+        }
+
+        let mut limit = _limit;
+
+        if offset + _limit > nfts.len()  {
+            limit = nfts.len() - offset;
+        }
+
+        return Ok(nfts[offset..(offset + limit)].to_vec());
+    }
+
+    pub fn get_amount(&self) -> usize {
+        return self.0.values().len();
+    }
 }
 
 #[query]
@@ -116,3 +137,15 @@ pub fn get_all() -> Vec<&'static NftCanister> {
     let db = ic::get_mut::<Registry>();
     db.get_all()
 }
+
+#[query]
+pub fn get_all_paginated(offset: Option<usize>, limit: Option<usize>) -> Result<GetAllPaginatedResponse>, OperationError> {
+    let db = ic::get_mut::<Registry>();
+    let nfts = db.get_all_paginated(offset.unwrap_or(0), limit.unwrap_or(DEFAULT_LIMIT))?;
+    let amount = db.get_amount();
+
+    return Ok(GetAllPaginatedResponse{
+        nfts,
+        amount,
+    });
+}