Question 1

How to generate a JSON Schema from a C# class using NJsonSchema?

Accepted Answer

Use JsonSchema.FromType<T>() with your .NET class, as shown in the README example. It leverages reflection and annotations to produce a schema, which can then be serialized to JSON with ToJson(). This is ideal for automating API contract generation from existing code.

Question 2

NJsonSchema vs System.Text.Json for JSON validation?

Accepted Answer

NJsonSchema focuses on JSON Schema-based validation with detailed error reporting and schema generation, while System.Text.Json provides basic JSON parsing and serialization. Choose NJsonSchema if you need structured schema validation or code generation; System.Text.Json is better for simple, high-performance JSON handling without schema dependencies.

Question 3

Can NJsonSchema handle JSON Schema draft 2020-12?

Accepted Answer

The README specifies support for JSON Schema draft v4+, and there's no mention of draft 2020-12. It may not fully support newer features like $dynamicRef or unevaluated properties, so check the wiki or issues for updates if you require the latest spec.

Question 4

How to validate JSON against a schema with NJsonSchema?

Accepted Answer

Load a schema using JsonSchema.FromJsonAsync() from a file or string, then call schema.Validate(jsonString) to get a list of validation errors. Each error includes path and kind, making it easy to debug JSON data compliance in .NET apps.

Question 5

What's the difference between NJsonSchema and NSwag?

Accepted Answer

NJsonSchema is the core library for JSON Schema operations, while NSwag builds on it to provide a full Swagger/OpenAPI toolchain for generating client code and UI. Use NJsonSchema for low-level schema handling; NSwag for end-to-end API workflow automation in .NET.

Question 6

How to generate TypeScript interfaces from C# classes with NJsonSchema?

Accepted Answer

First generate a JSON Schema from your .NET type using JsonSchema.FromType<T>(), then create a TypeScriptGenerator instance with the schema and call GenerateFile(). The README shows examples for both interfaces and classes with settings like TypeScriptTypeStyle.

Question 7

Are there any known performance issues with NJsonSchema?

Accepted Answer

Yes, reflection-based schema generation from complex .NET types can be slow, and validation of large JSON datasets might incur overhead. For high-throughput scenarios, consider caching schemas or benchmarking against alternatives like manual validation.

NJsonSchema

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