The database field address is a nullable varchar. When Radzen Blazor Studio generates a model from the table, it should use string? rather than string. The latest Visual Studio 2026 will not throw any compile errors, but it will cause runtime errors like below. At present, I can only make the program run properly by writing an extra tool to convert those nullable strings from string to string?.
fail: Microsoft.EntityFrameworkCore.Query[10100]
An exception occurred while iterating over the results of a query for context type 'YuyingWMS.Server.Data.WMSContext'.
System.InvalidCastException: Column 'address' is null.
at Npgsql.ThrowHelper.ThrowInvalidCastException_NoValue(FieldDescription field)
at Npgsql.NpgsqlDataReader.DbNullValueOrThrow[T](Int32 ordinal)
at Npgsql.NpgsqlDataReader.GetFieldValueCore[T](Int32 ordinal)
at Npgsql.NpgsqlDataReader.GetString(Int32 ordinal)
at lambda_method533(Closure, QueryContext, DbDataReader, ResultContext, SingleQueryResultCoordinator)
at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable1.Enumerator.MoveNext() System.InvalidCastException: Column 'address' is null. at Npgsql.ThrowHelper.ThrowInvalidCastException_NoValue(FieldDescription field) at Npgsql.NpgsqlDataReader.DbNullValueOrThrow[T](Int32 ordinal) at Npgsql.NpgsqlDataReader.GetFieldValueCore[T](Int32 ordinal) at Npgsql.NpgsqlDataReader.GetString(Int32 ordinal) at lambda_method533(Closure, QueryContext, DbDataReader, ResultContext, SingleQueryResultCoordinator) at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable1.Enumerator.MoveNext()
fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
An unhandled exception has occurred while executing the request.
System.InvalidCastException: Column 'address' is null.
at Npgsql.ThrowHelper.ThrowInvalidCastException_NoValue(FieldDescription field)
at Npgsql.NpgsqlDataReader.DbNullValueOrThrow[T](Int32 ordinal)
at Npgsql.NpgsqlDataReader.GetFieldValueCore[T](Int32 ordinal)
at Npgsql.NpgsqlDataReader.GetString(Int32 ordinal)
at lambda_method533(Closure, QueryContext, DbDataReader, ResultContext, SingleQueryResultCoordinator)
at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable1.Enumerator.MoveNext() at Microsoft.AspNetCore.OData.Formatter.Serialization.ODataResourceSetSerializer.WriteResourceSetAsync(IEnumerable enumerable, IEdmTypeReference resourceSetType, ODataWriter writer, ODataSerializerContext writeContext) at Microsoft.AspNetCore.OData.Formatter.Serialization.ODataResourceSetSerializer.WriteObjectInlineAsync(Object graph, IEdmTypeReference expectedType, ODataWriter writer, ODataSerializerContext writeContext) at Microsoft.AspNetCore.OData.Formatter.Serialization.ODataResourceSetSerializer.WriteObjectAsync(Object graph, Type type, ODataMessageWriter messageWriter, ODataSerializerContext writeContext) at Microsoft.AspNetCore.OData.Formatter.ODataOutputFormatterHelper.WriteToStreamAsync(Type type, Object value, IEdmModel model, ODataVersion version, Uri baseAddress, MediaTypeHeaderValue contentType, HttpRequest request, IHeaderDictionary requestHeaders, IODataSerializerProvider serializerProvider) at Microsoft.AspNetCore.OData.Formatter.ODataOutputFormatterHelper.WriteToStreamAsync(Type type, Object value, IEdmModel model, ODataVersion version, Uri baseAddress, MediaTypeHeaderValue contentType, HttpRequest request, IHeaderDictionary requestHeaders, IODataSerializerProvider serializerProvider) at Microsoft.AspNetCore.OData.Formatter.ODataOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters() --- End of stack trace from previous location --- at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|20_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope) at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context) warn: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[2] The response has already started, the error page middleware will not be executed. fail: Microsoft.AspNetCore.Server.Kestrel[13] Connection id "0HNJ2MAKNHGBG", Request id "0HNJ2MAKNHGBG:000001C3": An unhandled exception was thrown by the application. System.InvalidCastException: Column 'address' is null. at Npgsql.ThrowHelper.ThrowInvalidCastException_NoValue(FieldDescription field) at Npgsql.NpgsqlDataReader.DbNullValueOrThrow[T](Int32 ordinal) at Npgsql.NpgsqlDataReader.GetFieldValueCore[T](Int32 ordinal) at Npgsql.NpgsqlDataReader.GetString(Int32 ordinal) at lambda_method533(Closure, QueryContext, DbDataReader, ResultContext, SingleQueryResultCoordinator) at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable1.Enumerator.MoveNext()
at Microsoft.AspNetCore.OData.Formatter.Serialization.ODataResourceSetSerializer.WriteResourceSetAsync(IEnumerable enumerable, IEdmTypeReference resourceSetType, ODataWriter writer, ODataSerializerContext writeContext)
at Microsoft.AspNetCore.OData.Formatter.Serialization.ODataResourceSetSerializer.WriteObjectInlineAsync(Object graph, IEdmTypeReference expectedType, ODataWriter writer, ODataSerializerContext writeContext)
at Microsoft.AspNetCore.OData.Formatter.Serialization.ODataResourceSetSerializer.WriteObjectAsync(Object graph, Type type, ODataMessageWriter messageWriter, ODataSerializerContext writeContext)
at Microsoft.AspNetCore.OData.Formatter.ODataOutputFormatterHelper.WriteToStreamAsync(Type type, Object value, IEdmModel model, ODataVersion version, Uri baseAddress, MediaTypeHeaderValue contentType, HttpRequest request, IHeaderDictionary requestHeaders, IODataSerializerProvider serializerProvider)
at Microsoft.AspNetCore.OData.Formatter.ODataOutputFormatterHelper.WriteToStreamAsync(Type type, Object value, IEdmModel model, ODataVersion version, Uri baseAddress, MediaTypeHeaderValue contentType, HttpRequest request, IHeaderDictionary requestHeaders, IODataSerializerProvider serializerProvider)
at Microsoft.AspNetCore.OData.Formatter.ODataOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|20_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)
at Microsoft.WebTools.BrowserLink.Net.BrowserLinkMiddleware.InvokeAsync(HttpContext context)
at Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserRefreshMiddleware.InvokeAsync(HttpContext context)
at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)
