InvalidCastException in OpenBankingMapping.MapTransactionSummary when created_on is returned as a JSON array

[RadoslavSheytanovGP]

Summary

Retrieving the status of an Open Banking (GP-ECOM) transaction via ReportBuilder.Execute() throws an unhandled System.InvalidCastException from inside GlobalPayments.Api.dll.

The crash happens while mapping the report response when the created_on field arrives as a JSON array (parsed to List<string>) rather than a single scalar value. This exception is not caught and propagates out of the SDK, taking down the caller's execution thread.

Affected Versions

Confirmed present and unchanged in versions: 8.0.19, 9.0.0, 10.0.0, and 11.0.4 (current latest on NuGet). Upgrading does not resolve the issue as the underlying parsing logic remains identical across these releases.

Execution Flow

ReportBuilder.Execute()
└── OpenBankingProvider.ProcessReport
    └── OpenBankingMapping.MapReportResponse
        └── MapTransactionSummary

Stack Trace

System.InvalidCastException: Unable to cast object of type 'System.Collections.Generic.List`1[System.String]' to type 'System.DateTime'.
   at GlobalPayments.Api.Utils.JsonDoc.GetValue[T](String name, Func`2 converter)
   at GlobalPayments.Api.Mapping.OpenBankingMapping.MapTransactionSummary(JsonDoc response)
   at GlobalPayments.Api.Mapping.OpenBankingMapping.MapReportResponse`1(String rawResponse, ReportType reportType)
   at GlobalPayments.Api.Gateways.OpenBankingProvider.ProcessReport[T](ReportBuilder`1 builder)
   at GlobalPayments.Api.Builders.ReportBuilder`1.Execute(String configName)

---

Root Cause

The crash results from two interacting issues within src/GlobalPayments.Api/Utils/JsonUtils.cs:

1. Array Coercion to List<string>

In ParseObject, any field whose value is a JSON array of primitives/non-objects is eagerly stored via ParseTypeArray<string>:

else {
    var objs = ParseTypeArray<string>(child.Value as JArray, encoder);
    values.Add(child.Name, objs);   // Stored in the internal dictionary as List<string>
}

When a payload contains "created_on": ["2026-06-11T11:29:35Z"], a List<string> is stored under that dictionary key.

2. Double-Faulting in GetValue<T> Fallback

Convert.ChangeType throws an InvalidCastException because List<string> does not implement IConvertible. The catch block attempts a direct cast to T (DateTime), which immediately throws a second InvalidCastException. Because this second exception occurs inside the catch block, it escapes the method completely.

public T GetValue<T>(string name, Func<object, T> converter = null) {
    if (_dict.ContainsKey(name) && _dict[name] != null) {
        try {
            var value = _dict[name];
            // ...
            else return (T)Convert.ChangeType(value, typeof(T)); // Throws: List<string> is not IConvertible
        }                                                        
        catch (InvalidCastException) {
            return (T)_dict[name];                               // Throws AGAIN: Direct cast from List<string> to DateTime fails
        }                                                        
    }
    return default(T);
}

This path is triggered directly during transaction mapping in src/GlobalPayments.Api/Mapping/OpenBankingMapping.cs:

summary.TransactionDate = response.GetValue<DateTime>("created_on");

---

Steps to Reproduce

1. Execute a ReportBuilder query to fetch an Open Banking / bank-payment transaction status.
2. Ensure the upstream gateway maps or returns the created_on property wrapped inside a JSON array:

{
  "payments": [
    {
      "ob_trans_id": "example-id",
      "status": "CAPTURED",
      "amount": "10.00",
      "currency": "GBP",
      "created_on": ["2026-06-11T11:29:35Z"]
    }
  ]
}

3. The SDK will fail immediately with the InvalidCastException stack trace instead of returning a populated TransactionSummary object.

---

Expected Behavior

The SDK must handle type anomalies gracefully without throwing unhandled infrastructure exceptions. It should either:

• Extract and parse the first element when an array is unexpectedly provided for a scalar property.
• Degrade gracefully by returning default(T) if the internal data structure cannot be cast to the target type.

---

Suggested Fix

Tip

Resolving Fix 1 offers the highest value across the SDK, preventing unhandled dictionary casting failures for all types. Implementing Fix 2 guarantees that unexpected Open Banking array variants map to valid dates instead of zeroing out.

Fix 1: Harden GetValue<T> and GetNullableValue<T>

Safeguard the fallback path using a pattern matching or safe type check compatible with .NET Standard 1.3:

catch (InvalidCastException) {
    if (_dict[name] is T variable) return variable;
    return default(T);
}

Fix 2: Implement Array Tolerance in Open Banking Mappings

Update MapTransactionSummary to safely intercept and unpack string collections:

summary.TransactionDate = response.GetValue<DateTime>("created_on", o =>
    Convert.ToDateTime(o is System.Collections.IList list ? list[0] : o));

---

Note

This issue addresses SDK resilience. A separate engineering review should evaluate why the Open Banking gateway serialization pipeline wrapped the created_on timestamp in an array context in the first place.