abp-api-implementation

REST APIs in ABP Framework are implemented using AppServices that handle CRUD operations, DTO mapping, and business logic. Create an interface like `IProductAppService`, implement it with repository access, apply DTOs for request/response contracts, and use ABP's authorization attributes to enforce role-based access control on each method.

ABP provides `PageBy` for pagination and `WhereIf` for conditional filtering within application service methods. Combine these with DTOs that accept page size, page number, and filter parameters, then pass them to repository queries to return paginated, filtered results with metadata for client-side navigation.

ABP integrates FluentValidation for input validation on DTOs and uses authorization attributes on application service methods to enforce permissions. Define validation rules in DTO validators and apply `[Authorize]` or role-specific attributes to control who can access each endpoint based on ABP's permission system.

Yes, DTOs standardize API contracts in ABP by mapping domain entities to response objects, ensuring consistent data shapes across endpoints. Application services accept request DTOs, process them through repositories, map results to response DTOs, and return them—enabling uniform client-side consumption and reducing coupling to domain models.

ABP authorization uses declarative attributes and permission checks within application services. Apply `[Authorize]` for authentication, use policy-based attributes for fine-grained permissions, or call `AuthorizationService.CheckAsync` inside methods to verify role-based or resource-specific access before executing business logic.

ABP's modular architecture guides application service organization by domain, but the core practice—grouping related CRUD operations in services, using DTOs, and applying validation and authorization—applies to any ABP project. Modules provide dependency isolation and reusability; single-module apps benefit from the same patterns.