Fix the (de)serialization

types/types.go

@@ -192,16 +192,16 @@ func (i *EitherChainConfig) MarshalJSON() ([]byte, error) {
 }
 
 type ChainConfig struct {
-	ChainId      U256   `json:"chain_id"`
-	MaxBlockSize uint64 `json:"max_block_size"`
-	BaseFee      U256   `json:"base_fee"`
+	ChainId      U256Decimal `json:"chain_id"`
+	MaxBlockSize uint64      `json:"max_block_size"`
+	BaseFee      U256Decimal `json:"base_fee"`
 }
 
 func (self *ChainConfig) Commit() Commitment {
 	return NewRawCommitmentBuilder("CHAIN_CONFIG").
-		Uint256Field("chain_id", &self.ChainId).
+		Uint256Field("chain_id", self.ChainId.ToU256()).
 		Uint64Field("max_block_size", self.MaxBlockSize).
-		Uint256Field("base_fee", &self.BaseFee).
+		Uint256Field("base_fee", self.BaseFee.ToU256()).
 		Finalize()
 }
 
@@ -353,6 +353,31 @@ func (b *Bytes) UnmarshalJSON(in []byte) error {
 	return nil
 }
 
+// A readable decimal format for U256. Please use the struct `U256“ to initialize
+// the number first and use the `ToDecimal` to convert.
+type U256Decimal struct {
+	big.Int
+}
+
+func (i U256Decimal) MarshalJSON() ([]byte, error) {
+	return json.Marshal(i.Text(10))
+}
+
+func (i *U256Decimal) UnmarshalJSON(in []byte) error {
+	var s string
+	if err := json.Unmarshal(in, &s); err != nil {
+		return err
+	}
+	if _, err := fmt.Sscanf(s, "%d", &i.Int); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (i *U256Decimal) ToU256() *U256 {
+	return &U256{i.Int}
+}
+
 // A BigInt type which serializes to JSON a a hex string. This ensures compatibility with the
 // Espresso APIs.
 type U256 struct {
@@ -397,14 +422,18 @@ func (i *U256) UnmarshalJSON(in []byte) error {
 	return nil
 }
 
+func (i *U256) ToDecimal() *U256Decimal {
+	return &U256Decimal{i.Int}
+}
+
 type FeeInfo struct {
 	Account common.Address `json:"account"`
-	Amount  U256           `json:"amount"`
+	Amount  U256Decimal    `json:"amount"`
 }
 
 func (self *FeeInfo) Commit() Commitment {
 	return NewRawCommitmentBuilder("FEE_INFO").
 		FixedSizeField("account", self.Account.Bytes()).
-		Uint256Field("amount", &self.Amount).
+		Uint256Field("amount", self.Amount.ToU256()).
 		Finalize()
 }

types/types_test.go

@@ -32,7 +32,7 @@ var ReferenceNsTable NsTable = NsTable{
 
 var ReferenceChainConfig = &ResolvableChainConfig{
 	EitherChainConfig{
-		Left: &ChainConfig{ChainId: *NewU256().SetUint64(0x8a19), MaxBlockSize: 10240, BaseFee: *NewU256().SetUint64(0)},
+		Left: &ChainConfig{ChainId: *NewU256().SetUint64(0x8a19).ToDecimal(), MaxBlockSize: 10240, BaseFee: *NewU256().SetUint64(0).ToDecimal()},
 	},
 }
 
@@ -52,7 +52,7 @@ var ReferenceHeader Header = Header{
 	NsTable:             &ReferenceNsTable,
 	BlockMerkleTreeRoot: ReferenceBlockMerkleTreeRoot,
 	FeeMerkleTreeRoot:   ReferenceFeeMerkleTreeRoot,
-	FeeInfo:             &FeeInfo{Account: common.HexToAddress("0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266"), Amount: *NewU256().SetUint64(0)},
+	FeeInfo:             &FeeInfo{Account: common.HexToAddress("0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266"), Amount: *NewU256().SetUint64(0).ToDecimal()},
 }
 
 var ReferenceTransaction Transaction = Transaction{
@@ -86,7 +86,7 @@ func TestEspressoTypesL1BLockInfoJson(t *testing.T) {
 
 func TestEspressoTypesHeaderJson(t *testing.T) {
 	data := []byte(removeWhitespace(`{
-		"chain_config": { "chain_config": { "Left": { "chain_id": "0x8a19", "max_block_size": 10240, "base_fee": "0x0" } } },
+		"chain_config": { "chain_config": { "Left": { "chain_id": "35353", "max_block_size": 10240, "base_fee": "0" } } },
 		"height": 42,
 		"timestamp": 789,
 		"l1_head": 124,
@@ -102,7 +102,7 @@ func TestEspressoTypesHeaderJson(t *testing.T) {
 		},
 		"block_merkle_tree_root": "MERKLE_COMM~yB4_Aqa35_PoskgTpcCR1oVLh6BUdLHIs7erHKWi-usUAAAAAAAAAAEAAAAAAAAAJg",
 		"fee_merkle_tree_root": "MERKLE_COMM~VJ9z239aP9GZDrHp3VxwPd_0l28Hc5KEAB1pFeCIxhYgAAAAAAAAAAIAAAAAAAAAdA",
-		"fee_info":{"account":"0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266","amount":"0x0"}
+		"fee_info":{"account":"0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266","amount":"0"}
 	}`))
 
 	// Check encoding.