The JSON property 'item' is defined multiple times on type 'System.Text.Json.Nodes.JsonNode'.

[Tragedie-v-JZD]

On our project, we have several classes that are part of API responses, and some of their fields are type of JsonNode

Example of class definitioin:

`public class FieldDefinitionModel { ///

/// Gets or sets a code of the field. ///

public string Code { get; set; }

    /// <summary>
    /// Gets or sets a label of the field.
    /// </summary>
    public string Label { get; set; }

    /// <summary>
    /// Gets or sets a text associated to the field.
    /// </summary>
    public string Text { get; set; }

    /// <summary>
    /// Gets or sets a hint associated to the field.
    /// </summary>
    public string Hint { get; set; }

    /// <summary>
    /// Gets a help text.
    /// </summary>
    public string Help { get; }

    /// <summary>
    /// Gets or sets a structured data describing alowed values for this field.
    /// </summary>
    public IList<AllowedFieldDefinitionModel>? AllowedValues { get; set; }

    /// <summary>
    /// Gets or sets a value indicating whether field is visible.
    /// </summary>
    public bool Visible { get; set; }

    /// <summary>
    /// Gets or sets a value indicating whether field is mandatory.
    /// </summary>
    public bool Mandatory { get; set; }

    /// <summary>
    /// Gets or sets a value on which the field depends.
    /// </summary>
    public string[]? DependsOnFields { get; set; }

    /// <summary>
    /// Gets or sets a collection of values triggering visibility of the field.
    /// </summary>
    public string[]? VisibleOnValues { get; set; }

    /// <summary>
    /// Gets or sets a collection of values triggering non-visibility of the field.
    /// </summary>
    public string[]? HiddenOnValues { get; set; }

    /// <summary>
    /// Gets or sets an complex dependency.
    /// </summary>
    public JsonNode? ComplexDependency { get; set; }

    /// <summary>
    /// Gets or sets a config value of the field.
    /// </summary>
    public string FieldConfig { get; set; }

    /// <summary>
    /// Gets or sets a config value of the field.
    /// </summary>
    public string FieldConfig2 { get; set; }

    /// <summary>
    /// Gets or sets a config value of the field.
    /// </summary>
    public string FieldConfig3 { get; set; }

    /// <summary>
    /// Gets or sets a css class of the field.
    /// </summary>
    public string CssClass { get; set; }

    /// <summary>
    /// Gets or sets a value indicating whether is allowed to upload data of field.
    /// </summary>
    public bool AllowUpload { get; set; }
}

` Now we switched from .NET 7 to .NET 8 and togetheter with that we switched from NSwag 13.20.0 to 14.0.3

In 13.20 it works as expected, but after switch to 14.0.3 generation of swagger.json ends up with following

3>Executing file 'nswag.json' with variables 'Configuration=Debug'... 3>Launcher directory: C:\Users\tknaifl001\.nuget\packages\nswag.msbuild\14.0.3\tools\Net80 3>System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. 3> ---> System.InvalidOperationException: The JSON property 'item' is defined multiple times on type 'System.Text.Json.Nodes.JsonNode'. 3> at NJsonSchema.Generation.SystemTextJsonReflectionService.GenerateProperties(JsonSchema schema, ContextualType contextualType, SystemTextJsonSchemaGeneratorSettings settings, JsonSchemaGenerator schemaGenerator, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.ReflectionServiceBase1.NJsonSchema.Generation.IReflectionService.GenerateProperties(JsonSchema schema, ContextualType contextualType, JsonSchemaGeneratorSettings settings, JsonSchemaGenerator schemaGenerator, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.GenerateObject(JsonSchema schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NSwag.Generation.OpenApiSchemaGenerator.GenerateObject(JsonSchema schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](TSchemaType schema, ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](Type type, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate(Type type, JsonSchemaResolver schemaResolver) 3> at NSwag.Generation.OpenApiSchemaGenerator.GenerateObject(JsonSchema schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](TSchemaType schema, ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.GenerateWithReferenceAndNullability[TSchemaType](ContextualType contextualType, Boolean isNullable, JsonSchemaResolver schemaResolver, Action2 transformation) 3> at NSwag.Generation.OpenApiSchemaGenerator.GenerateWithReferenceAndNullability[TSchemaType](ContextualType contextualType, Boolean isNullable, JsonSchemaResolver schemaResolver, Action2 transformation) 3> at NJsonSchema.Generation.JsonSchemaGenerator.AddProperty(JsonSchema parentSchema, ContextualAccessorInfo property, JsonTypeDescription propertyTypeDescription, String propertyName, Attribute requiredAttribute, Boolean hasRequiredAttribute, Boolean isNullable, Object defaultValue, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.SystemTextJsonReflectionService.GenerateProperties(JsonSchema schema, ContextualType contextualType, SystemTextJsonSchemaGeneratorSettings settings, JsonSchemaGenerator schemaGenerator, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.ReflectionServiceBase1.NJsonSchema.Generation.IReflectionService.GenerateProperties(JsonSchema schema, ContextualType contextualType, JsonSchemaGeneratorSettings settings, JsonSchemaGenerator schemaGenerator, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.GenerateObject(JsonSchema schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NSwag.Generation.OpenApiSchemaGenerator.GenerateObject(JsonSchema schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](TSchemaType schema, ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](Type type, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate(Type type, JsonSchemaResolver schemaResolver) 3> at NSwag.Generation.OpenApiSchemaGenerator.GenerateObject(JsonSchema schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](TSchemaType schema, ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.GenerateWithReferenceAndNullability[TSchemaType](ContextualType contextualType, Boolean isNullable, JsonSchemaResolver schemaResolver, Action2 transformation) 3> at NSwag.Generation.OpenApiSchemaGenerator.GenerateWithReferenceAndNullability[TSchemaType](ContextualType contextualType, Boolean isNullable, JsonSchemaResolver schemaResolver, Action2 transformation) 3> at NJsonSchema.Generation.JsonSchemaGenerator.GenerateArray[TSchemaType](TSchemaType schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](TSchemaType schema, ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.GenerateWithReferenceAndNullability[TSchemaType](ContextualType contextualType, Boolean isNullable, JsonSchemaResolver schemaResolver, Action2 transformation) 3> at NSwag.Generation.OpenApiSchemaGenerator.GenerateWithReferenceAndNullability[TSchemaType](ContextualType contextualType, Boolean isNullable, JsonSchemaResolver schemaResolver, Action2 transformation) 3> at NJsonSchema.Generation.JsonSchemaGenerator.AddProperty(JsonSchema parentSchema, ContextualAccessorInfo property, JsonTypeDescription propertyTypeDescription, String propertyName, Attribute requiredAttribute, Boolean hasRequiredAttribute, Boolean isNullable, Object defaultValue, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.SystemTextJsonReflectionService.GenerateProperties(JsonSchema schema, ContextualType contextualType, SystemTextJsonSchemaGeneratorSettings settings, JsonSchemaGenerator schemaGenerator, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.ReflectionServiceBase1.NJsonSchema.Generation.IReflectionService.GenerateProperties(JsonSchema schema, ContextualType contextualType, JsonSchemaGeneratorSettings settings, JsonSchemaGenerator schemaGenerator, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.GenerateObject(JsonSchema schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NSwag.Generation.OpenApiSchemaGenerator.GenerateObject(JsonSchema schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](TSchemaType schema, ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](Type type, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate(Type type, JsonSchemaResolver schemaResolver) 3> at NSwag.Generation.OpenApiSchemaGenerator.GenerateObject(JsonSchema schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](TSchemaType schema, ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate(ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.GenerateInheritance(ContextualType type, JsonSchema schema, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.GenerateObject(JsonSchema schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NSwag.Generation.OpenApiSchemaGenerator.GenerateObject(JsonSchema schema, JsonTypeDescription typeDescription, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](TSchemaType schema, ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.Generate[TSchemaType](ContextualType contextualType, JsonSchemaResolver schemaResolver) 3> at NJsonSchema.Generation.JsonSchemaGenerator.GenerateWithReferenceAndNullability[TSchemaType](ContextualType contextualType, Boolean isNullable, JsonSchemaResolver schemaResolver, Action2 transformation) 3> at NSwag.Generation.OpenApiSchemaGenerator.GenerateWithReferenceAndNullability[TSchemaType](ContextualType contextualType, Boolean isNullable, JsonSchemaResolver schemaResolver, Action2 transformation) 3> at NSwag.Generation.AspNetCore.Processors.OperationResponseProcessor.Process(OperationProcessorContext operationProcessorContext) 3> at NSwag.Generation.AspNetCore.AspNetCoreOpenApiDocumentGenerator.RunOperationProcessors(OpenApiDocument document, ApiDescription apiDescription, Type controllerType, MethodInfo methodInfo, OpenApiOperationDescription operationDescription, List1 allOperations, OpenApiDocumentGenerator generator, OpenApiSchemaResolver schemaResolver) 3> at NSwag.Generation.AspNetCore.AspNetCoreOpenApiDocumentGenerator.AddOperationDescriptionsToDocument(OpenApiDocument document, Type controllerType, List1 operations, OpenApiDocumentGenerator swaggerGenerator, OpenApiSchemaResolver schemaResolver) 3> at NSwag.Generation.AspNetCore.AspNetCoreOpenApiDocumentGenerator.GenerateApiGroups(OpenApiDocumentGenerator generator, OpenApiDocument document, IGrouping2[] apiGroups, OpenApiSchemaResolver schemaResolver) 3> at NSwag.Generation.AspNetCore.AspNetCoreOpenApiDocumentGenerator.GenerateAsync(ApiDescriptionGroupCollection apiDescriptionGroups) 3> at NSwag.Commands.Generation.AspNetCore.AspNetCoreToOpenApiCommand.GenerateDocumentWithDocumentProviderAsync(IServiceProvider serviceProvider) in /_/src/NSwag.Commands/Commands/Generation/AspNetCore/AspNetCoreToOpenApiCommand.cs:line 245 3> at NSwag.Commands.Generation.AspNetCore.AspNetCoreToOpenApiCommand.GenerateDocumentAsync(IServiceProvider serviceProvider, String currentWorkingDirectory) in /_/src/NSwag.Commands/Commands/Generation/AspNetCore/AspNetCoreToOpenApiCommand.cs:line 239 3> at NSwag.Commands.Generation.AspNetCore.AspNetCoreToOpenApiGeneratorCommandEntryPoint.Process(String commandContent, String outputFile, String applicationName) in /_/src/NSwag.Commands/Commands/Generation/AspNetCore/AspNetCoreToOpenApiGeneratorCommandEntryPoint.cs:line 29 3> at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor) 3> at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span1 copyOfArgs, BindingFlags invokeAttr) 3> --- End of inner exception stack trace --- 3> at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span1 copyOfArgs, BindingFlags invokeAttr) 3> at System.Reflection.MethodBaseInvoker.InvokeWithFewArgs(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) 3> at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters) 3> at NSwag.AspNetCore.Launcher.Program.Main(String[] args) in /_/src/NSwag.AspNetCore.Launcher/Program.cs:line 132

How to properly handle JsonNode in model classes?

Thx

[devployment]

Just hit the exact same issue. Anybody found out what the problem is?

[maikebing]

Just hit the exact same issue. Anybody found out what the problem is?