Improve schema decoding errors

backend-rust/CHANGELOG.md

@@ -22,6 +22,7 @@ Database schema version: 2
 
 ### Fixed
 
+- Fix button to display the schema decoding error at front-end by returning the error as an object.
 - Fix typo in `versions` endpoint.
 - Fix unit conversion for `avg_finalization_time` in `Query::block_metrics`.
 - Issue for `Query::transaction_metrics` producing an internal error when query period is beyond the genesis block.

backend-rust/src/migrations/m0001-initialize.sql

@@ -841,6 +841,7 @@ CREATE INDEX block_special_transaction_outcomes_idx
 
 -- Function for generating a table where each row is a bucket.
 -- Used by metrics queries.
+-- This function is replaced with a function of the same name in migration file `m0002`.
 CREATE OR REPLACE FUNCTION date_bin_series(bucket_size interval, starting TIMESTAMPTZ, ending TIMESTAMPTZ)
 RETURNS TABLE(bucket_start TIMESTAMPTZ, bucket_end TIMESTAMPTZ) AS $$
     SELECT

backend-rust/src/transaction_event/smart_contracts.rs

@@ -11,6 +11,8 @@ use concordium_rust_sdk::base::{
     },
     smart_contracts::ReceiveName,
 };
+use serde::Serialize;
+use serde_json::to_string;
 
 #[derive(Enum, Copy, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
 pub enum ContractVersion {
@@ -118,7 +120,7 @@ impl ContractInitialized {
                 opt_event_schema.as_ref(),
                 log,
                 SmartContractSchemaNames::Event,
-            );
+            )?;
 
             connection.edges.push(connection::Edge::new(index.to_string(), decoded_log));
         }
@@ -190,7 +192,7 @@ impl ContractUpdated {
             opt_receive_param_schema.as_ref(),
             &self.input_parameter,
             SmartContractSchemaNames::InputParameterReceiveFunction,
-        );
+        )?;
 
         Ok(Some(decoded_input_parameter))
     }
@@ -250,7 +252,7 @@ impl ContractUpdated {
                 opt_event_schema.as_ref(),
                 log,
                 SmartContractSchemaNames::Event,
-            );
+            )?;
 
             connection.edges.push(connection::Edge::new(index.to_string(), decoded_log));
         }
@@ -331,7 +333,7 @@ impl ContractInterrupted {
                 opt_event_schema.as_ref(),
                 log,
                 SmartContractSchemaNames::Event,
-            );
+            )?;
 
             connection.edges.push(connection::Edge::new(index.to_string(), decoded_log));
         }
@@ -394,38 +396,53 @@ impl SmartContractSchemaNames {
     }
 }
 
+/// Schema decoding error reported to the front-end.
+#[derive(Serialize)]
+struct SchemaDecodingError {
+    error: String,
+}
+
 fn decode_value_with_schema(
     opt_schema: Option<&Type>,
     value: &[u8],
     schema_name: SmartContractSchemaNames,
-) -> String {
+) -> Result<String, ApiError> {
     let Some(schema) = opt_schema else {
         // Note: There could be something better displayed than this string if no schema
         // is available for decoding at the frontend long-term.
-        return format!(
-            "No embedded {} schema in smart contract available for decoding",
-            schema_name.kind()
-        );
+        return to_string(&SchemaDecodingError {
+                     error: format!(
+                          "No embedded {} schema in smart contract available for decoding",
+                     schema_name.kind()
+                    ),
+                   }) .map_err(|_| ApiError::InternalError("Should be valid error string".to_string()));     
     };
 
     let mut cursor = Cursor::new(&value);
+
     match schema.to_json(&mut cursor) {
         Ok(v) => {
-            serde_json::to_string(&v).unwrap_or_else(|e| {
-                // We don't return an error here since the query is correctly formed and
-                // the CCDScan backend is working as expected.
-                // A wrong/missing schema is a mistake by the smart contract
-                // developer which in general cannot be fixed after the deployment of
-                // the contract. We display the error message (instead of the decoded
-                // value) in the block explorer to make the info visible to the smart
-                // contract developer for debugging purposes here.
-                format!(
-                    "Failed to deserialize {} with {} schema into string: {:?}",
-                    schema_name.value(),
-                    schema_name.kind(),
-                    e
-                )
-            })
+            match serde_json::to_string(&v) {
+                Ok(v) => Ok(v),
+                Err(_) => {
+                    // We don't return an error here since the query is correctly formed and
+                    // the CCDScan backend is working as expected.
+                    // A wrong/missing schema is a mistake by the smart contract
+                    // developer which in general cannot be fixed after the deployment of
+                    // the contract. We display the error message (instead of the decoded
+                    // value) in the block explorer to make the info visible to the smart
+                    // contract developer for debugging purposes here.
+                    Ok(to_string(&SchemaDecodingError {
+                        error: format!(
+                            "No embedded {} schema in smart contract available for decoding",
+                            schema_name.kind()
+                        ),
+                    })
+                    .map_err(|_| {
+                        ApiError::InternalError("Should be valid error string".to_string())
+                    })?)
+                }
+            }
         }
         Err(e) => {
             // We don't return an error here since the query is correctly formed and
@@ -435,12 +452,15 @@ fn decode_value_with_schema(
             // the contract. We display the error message (instead of the decoded
             // value) in the block explorer to make the info visible to the smart
             // contract developer for debugging purposes here.
-            format!(
-                "Failed to deserialize {} with {} schema: {:?}",
-                schema_name.value(),
-                schema_name.kind(),
-                e.display(true)
-            )
+            Ok(to_string(&SchemaDecodingError {
+                error: format!(
+                    "Failed to deserialize {} with {} schema: {:?}",
+                    schema_name.value(),
+                    schema_name.kind(),
+                    e.display(true)
+                ),
+            })
+            .map_err(|_| ApiError::InternalError("Should be valid error string".to_string()))?)
         }
     }
 }