𝗛𝗮𝗻𝗱𝗹𝗶𝗻𝗴 𝗩𝗮𝗹𝗶𝗱𝗮𝘁𝗶𝗼𝗻𝘀 𝗶𝗻 𝗠𝗶𝗻𝗶𝗺𝗮𝗹 𝗔𝗣𝗜 – 𝗪𝗵𝗮𝘁’𝘀 𝗡𝗲𝘄 𝗳𝗿𝗼𝗺 .𝗡𝗘𝗧 𝟲 𝘁𝗼 .𝗡𝗘𝗧 𝟭𝟬

Validation in Minimal APIs has improved a lot! Here's how it changed over time:

🔹 .𝗡𝗘𝗧 𝟲 & 𝟳
– No built-in validation support
– You had to write custom code manually like:

var context = new ValidationContext(model);
Validator.TryValidateObject(model, context, results, true);

🔹 .𝗡𝗘𝗧 𝟴
– Built-in validation support introduced
– Simply add validation service:

builder.Services.AddValidation();

– Use [Validate] attribute in Minimal API:

app.MapPost("/register", ([Validate] UserModel user) =>
Results.Ok("Valid user"));

– Invalid data? You automatically get a 400 Bad Request with error details

🔹 .𝗡𝗘𝗧 𝟭𝟬 – 𝗠𝗼𝗿𝗲 𝗣𝗼𝘄𝗲𝗿𝗳𝘂𝗹
– Now validates:

• Query parameters
• Headers
• Request body

– You can use 𝗿𝗲𝗰𝗼𝗿𝗱 𝘁𝘆𝗽𝗲𝘀 with validation attributes:

public record Product(
[Required] string Name,
[Range(1, 1000)] int Quantity);

– Mapping:

app.MapPost("/products", (Product product) =>
TypedResults.Ok(product));

– Want to 𝗱𝗶𝘀𝗮𝗯𝗹𝗲 𝘃𝗮𝗹𝗶𝗱𝗮𝘁𝗶𝗼𝗻 for a specific endpoint?

app.MapPost("/products",
([EvenNumber(ErrorMessage = "Product ID must be even")] int productId, [Required] string name) =>
TypedResults.Ok(productId))
.DisableValidation();

𝗛𝗼𝘄 𝗮𝗿𝗲 𝘆𝗼𝘂 𝗵𝗮𝗻𝗱𝗹𝗶𝗻𝗴 𝘃𝗮𝗹𝗶𝗱𝗮𝘁𝗶𝗼𝗻 𝗶𝗻 𝘆𝗼𝘂𝗿 𝗔𝗣𝗜𝘀 𝘁𝗼𝗱𝗮𝘆?
𝗛𝗮𝘃𝗲 𝘆𝗼𝘂 𝘁𝗿𝗶𝗲𝗱 𝘁𝗵𝗲 𝗻𝗲𝘄 [𝗩𝗮𝗹𝗶𝗱𝗮𝘁𝗲] 𝗮𝘁𝘁𝗿𝗶𝗯𝘂𝘁𝗲 𝗶𝗻 .𝗡𝗘𝗧 𝟴 𝗼𝗿 .𝗡𝗘𝗧 𝟭𝟬?