XData + Aurelius: Swagger/OpenAPI fails when entity contains TDynamicProperties (EJsonGeneratorNotFound)

BIZ TMS XData
1

Subject: XData + Aurelius: Swagger/OpenAPI fails when entity contains TDynamicProperties (EJsonGeneratorNotFound)

Hello,

we are using Aurelius with XData, including dynamic fields via

FireDacMySqlConnection.DefineMappingSetup(TMappingExplorer.DefaultInstance);

Dynamic properties work correctly inside Aurelius ORM.
The problem occurs only when an entity containing TDynamicProperties is used as a return type in an XData service.

Example service:

function GetOrders: TObjectList<Tc_order>;

The moment Swagger/OpenAPI tries to generate the schema, XData crashes with:

Stack trace excerpt:

XData.JSchema.Generators.TJSchemaGenerators.Get
XData.JSchema.Generators.TJSchemaGenerators.ProcessRef
XData.OpenAPI.Builder.TOpenApiBuilder.BuildSchema
XData.OpenAPI.Builder.TOpenApiBuilder.Build
SwaggerDocument(...)

OpenAPI generation fails even before the service is called.

Entity example (simplified):

type
  Tc_Order = class
  private
    [XDataExcludeProperty]
    [JsonIgnore]
    FDynCon: TDynamicProperties;

    [XDataExcludeProperty]
    [JsonIgnore]
    property DynCon: TDynamicProperties read FDynCon;

    …
  end;

We tried all combinations:

  • exclude attribute on field
  • exclude attribute on property
  • exclude on both
  • remove property, leave only field
  • replace type with TValue, TObject, Variant
  • wrap the dynamic properties into another class
  • return DTO without dynamic fields

The result is always the same:
Swagger/OpenAPI generator tries to reflect TDynamicProperties = TDictionary<string, TValue>
→ and crashes on TDictionary<string, TValue>.TItem, because TValue has no JSON generator registered.

Even when both property and field are marked with [XDataExcludeProperty] and [JsonIgnore], the generator still attempts to inspect the type.

Important notes:

  • ORM functionality works fine
  • Methods execute correctly when Swagger is disabled
  • The crash happens only during OpenAPI/Swagger schema generation
  • XData attempts to generate schema for TValue, even though it is excluded

Questions:

  1. What is the correct way to completely exclude TDynamicProperties from OpenAPI/Swagger generation so XData does not inspect it at all?
  2. Is there a recommended pattern for using TDynamicProperties with XData entities?
  3. Should a custom JSON generator be registered for TValue, or is this type intentionally unsupported?
  4. Is wrapping the entity into a DTO the only supported solution, or is there a built-in mechanism to hide dynamic properties?

Minimal reproducible example:

This minimal entity is enough to trigger the error:

type
  TTestEntity = class
  private
    [XDataExcludeProperty]
    property DynCon: TDynamicProperties read FDynCon;
  end;

Calling:

function GetAll: TObjectList<TTestEntity>;

→ Immediately results in:

Any guidance on the proper way to exclude or handle TDynamicProperties in XData OpenAPI generation would be greatly appreciated.

Thank you!

2

Can you please send a minimal compilable project reproducing the issue?

1 Like
3

I'll try to have the code sample ready tomorrow or on Friday.

4

for_wagner_json_error.zip (2.3 MB)

This is minimal code sample. In memo are 2 URLs. Worked / Crashed
in database directory is sql dump.

i’m very sorry for late response.

Petr

5

Unfortunately I can't compile your application. I even tried to fix some compilation problems, but there is a gazillion of dependencies and 3rd party components (UniDac, Zeos, DevExpress and many others I don't even know what they are) so I gave up. There is even things related to visual controls which I believe are not needed at all to reproduce it.

Could you please clean it up to a minimum setup?

6

for_wagner_json_error_cleaned.zip (2.6 MB)

I’m very sorry. My mistake. Please try this version

Petr

7

Reason for the error is that your second XData server (the one that fails) is mapped to model Model2. But your service references a class that does not belong to that model.

You should add such class to model Model2 so XData can treat it as an entity:

  [Entity]
  [Table('c_order')]
  [Description('Zakázky')]
  [Model('Model2'), Model('Default')] // ADD THIS LINE
  [UniqueKey('bar_id')]
  [Id('Fid', TIdGenerator.IdentityOrSequence)]
  Tc_order = class(TTMSAGObject)
8

Thanks, Wagner.

I've been suspecting the whole time that it would be an absolutely stupid problem.
We understand it now.

Thanks Petr

1 Like
9

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