refactor(metadata): Add deserializer for denom_units and aliases to handle null values

Author: BigtoC

packages/std/src/metadata.rs

@@ -1,12 +1,13 @@
 use schemars::JsonSchema;
-use serde::{Deserialize, Serialize};
+use serde::{Deserialize, Deserializer, Serialize};
 
 use crate::prelude::*;
 
 /// Replicates the cosmos-sdk bank module Metadata type
 #[derive(Serialize, Deserialize, Clone, Default, Debug, PartialEq, Eq, JsonSchema)]
 pub struct DenomMetadata {
     pub description: String,
+    #[serde(deserialize_with = "deserialize_null_default")]
     pub denom_units: Vec<DenomUnit>,
     pub base: String,
     pub display: String,
@@ -21,27 +22,15 @@ pub struct DenomMetadata {
 pub struct DenomUnit {
     pub denom: String,
     pub exponent: u32,
+    #[serde(deserialize_with = "deserialize_null_default")]
     pub aliases: Vec<String>,
 }
 
-#[derive(Serialize, Deserialize, Clone, Default, Debug, PartialEq, Eq, JsonSchema)]
-pub struct NullableDenomMetadata {
-    pub description: String,
-    // denom_units is nullable: https://github.com/cosmos/cosmos-sdk/blob/main/api/cosmos/bank/v1beta1/bank.pulsar.go#L4539
-    pub denom_units: Option<Vec<NullableDenomUnit>>,
-    pub base: String,
-    pub display: String,
-    pub name: String,
-    pub symbol: String,
-    pub uri: String,
-    pub uri_hash: String,
-}
-
-/// Replicates the cosmos-sdk bank module DenomUnit type
-#[derive(Serialize, Deserialize, Clone, Default, Debug, PartialEq, Eq, JsonSchema)]
-pub struct NullableDenomUnit {
-    pub denom: String,
-    pub exponent: u32,
-    // aliases is nullable: https://github.com/cosmos/cosmos-sdk/blob/main/api/cosmos/bank/v1beta1/bank.pulsar.go#L4478
-    pub aliases: Option<Vec<String>>,
+fn deserialize_null_default<'de, D, T>(deserializer: D) -> Result<T, D::Error>
+where
+    T: Default + Deserialize<'de>,
+    D: Deserializer<'de>,
+{
+    let opt = Option::deserialize(deserializer)?;
+    Ok(opt.unwrap_or_default())
 }