Merge pull request #446 from oasisprotocol/mitjat/evm-token-type-opti…

…onal

api: EVM tokens: output only tokesn of supported types; fix error generation

api/errors.go

@@ -27,7 +27,13 @@ var (
 
 type ErrStorageError struct{ Err error }
 
-func (e ErrStorageError) Error() string { return fmt.Sprintf("storage error: %s", e.Err.Error()) }
+func (e ErrStorageError) Error() string {
+	if e.Err != nil {
+		return fmt.Sprintf("storage error: %s", e.Err.Error())
+	}
+	// ErrStorageError shouldn't be constructed with a nil Err, but format it just in case.
+	return "storage error: internal bug, incorrectly instantiated error object with nil"
+}
 
 func HttpCodeForError(err error) int {
 	errVal := reflect.ValueOf(err)

api/spec/v1.yaml

@@ -1686,7 +1686,7 @@ components:
     RuntimeEvmBalance:
       description: Balance of an account for a specific runtime and EVM token.
       type: object
-      required: [balance, token_contract_addr, token_decimals]
+      required: [balance, token_contract_addr, token_decimals, token_type]
       properties:
         balance:
           <<: *BigIntType
@@ -2335,9 +2335,9 @@ components:
       type: string
       enum:
         - ERC20
-        - ERC721
-        - ERC1155
-        - OasisSdk
+        # Desired support in the future, among others:
+        # - ERC721
+        # - ERC1155
       description: |
         The type of a EVM token.
 

storage/client/client.go

@@ -627,7 +627,7 @@ func (c *StorageClient) Account(ctx context.Context, address staking.Address) (*
 		address.String(),
 	)
 	if queryErr != nil {
-		return nil, wrapError(err)
+		return nil, wrapError(queryErr)
 	}
 	defer allowanceRows.Close()
 
@@ -1451,7 +1451,7 @@ func (c *StorageClient) RuntimeTokens(ctx context.Context, p apiTypes.GetRuntime
 			&t.Type,
 			&t.NumHolders,
 		); err2 != nil {
-			return nil, wrapError(err)
+			return nil, wrapError(err2)
 		}
 
 		ts.EvmTokens = append(ts.EvmTokens, t)

storage/client/queries/queries.go

@@ -440,14 +440,17 @@ const (
 			tokens.symbol,
 			tokens.decimals,
 			tokens.total_supply,
-			CASE
+			CASE -- NOTE: There are two queries that use this CASE via copy-paste; edit both if changing.
 				WHEN tokens.token_type = 20 THEN 'ERC20'
+				ELSE 'unexpected_other_type' -- Our openapi spec doesn't allow us to output this, but better this than a null value (which causes nil dereference)
 			END AS type,
 			holders.cnt AS num_holders
 		FROM chain.evm_tokens AS tokens
 		JOIN chain.address_preimages AS preimages ON (token_address = preimages.address)
 		JOIN holders USING (token_address)
-		WHERE (tokens.runtime = $1)
+		WHERE
+			(tokens.runtime = $1) AND
+			tokens.token_type != 0 -- exclude unknown-type tokens; they're often just contracts that emitted Transfer events but don't expose the token ticker, name, balance etc.
 		ORDER BY num_holders DESC
 		LIMIT $2::bigint
 		OFFSET $3::bigint`
@@ -470,13 +473,17 @@ const (
 			balances.token_address AS token_address,
 			tokens.symbol AS token_symbol,
 			tokens.token_name AS token_name,
-			'ERC20' AS token_type,  -- TODO: fetch from the table once available
+			CASE -- NOTE: There are two queries that use this CASE via copy-paste; edit both if changing.
+				WHEN tokens.token_type = 20 THEN 'ERC20'
+				ELSE 'unexpected_other_type' -- Our openapi spec doesn't allow us to output this, but better this than a null value (which causes nil dereference)
+			END AS token_type,
 			tokens.decimals AS token_decimals
 		FROM chain.evm_token_balances AS balances
 		JOIN chain.evm_tokens         AS tokens USING (runtime, token_address)
 		WHERE runtime = $1 AND
-			account_address = $2::text AND
-			balance != 0
+			balances.account_address = $2::text AND
+			tokens.token_type != 0 AND -- exclude unknown-type tokens; they're often just contracts that emitted Transfer events but don't expose the token ticker, name, balance etc.
+			balances.balance != 0
 		ORDER BY balance DESC
 		LIMIT 1000  -- To prevent huge responses. Hardcoded because API exposes this as a subfield that does not lend itself to pagination.
 	`