Port and Adapter Specification

This is the API specification for Port interfaces, Adapter implementation base classes, the Specification pattern, DI registration, and source generator attributes provided by the Functorium framework. For design principles and implementation guides, see Port Architecture and Definitions and Adapter Implementation.

Summary

Key Types

Type	Namespace	Description
`IObservablePort`	`Functorium.Abstractions.Observabilities`	Base interface for all Ports/Adapters (provides Observability category)
`IRepository<TAggregate, TId>`	`Functorium.Domains.Repositories`	Aggregate Root level Repository CRUD contract
`IQueryPort`	`Functorium.Applications.Queries`	Non-generic QueryPort marker interface
`IQueryPort<TEntity, TDto>`	`Functorium.Applications.Queries`	Specification-based query + pagination contract
`PageRequest`	`Functorium.Applications.Queries`	Offset-based pagination request
`PagedResult<T>`	`Functorium.Applications.Queries`	Offset-based pagination result
`CursorPageRequest`	`Functorium.Applications.Queries`	Keyset(Cursor)-based pagination request
`CursorPagedResult<T>`	`Functorium.Applications.Queries`	Keyset(Cursor)-based pagination result
`SortExpression`	`Functorium.Applications.Queries`	Multi-field sort expression
`SortField`	`Functorium.Applications.Queries`	Sort field + direction pair
`SortDirection`	`Functorium.Applications.Queries`	Sort direction SmartEnum (`Ascending`, `Descending`)
`Specification<T>`	`Functorium.Domains.Specifications`	Specification pattern abstract base class
`ExpressionSpecification<T>`	`Functorium.Domains.Specifications`	Expression Tree-based Specification abstract class
`IExpressionSpec<T>`	`Functorium.Domains.Specifications`	Interface indicating Expression Tree provision capability
`PropertyMap<TEntity, TModel>`	`Functorium.Domains.Specifications.Expressions`	Entity-Model Expression auto-conversion property mapping
`SpecificationExpressionResolver`	`Functorium.Domains.Specifications.Expressions`	Utility for extracting/composing Expression Trees from Specifications
`EfCoreRepositoryBase<TAggregate, TId, TModel>`	`Functorium.Adapters.Repositories`	EF Core Repository common base class
`InMemoryRepositoryBase<TAggregate, TId>`	`Functorium.Adapters.Repositories`	InMemory Repository common base class
`DapperQueryBase<TEntity, TDto>`	`Functorium.Adapters.Repositories`	Dapper-based QueryAdapter common base class
`InMemoryQueryBase<TEntity, TDto>`	`Functorium.Adapters.Repositories`	InMemory QueryAdapter common base class
`DapperSpecTranslator<TEntity>`	`Functorium.Adapters.Repositories`	Specification to SQL WHERE clause translation registry
`IHasStringId`	`Functorium.Adapters.Repositories`	Common string Id interface for EF Core models
`ObservablePortRegistration`	`Functorium.Abstractions.Registrations`	Observable Port DI registration extension methods
`OptionsConfigurator`	`Functorium.Adapters.Abstractions.Options`	FluentValidation-based options validation registration
`GenerateObservablePortAttribute`	`Functorium.Adapters.SourceGenerators`	Observable wrapper auto-generation attribute
`ObservablePortIgnoreAttribute`	`Functorium.Adapters.SourceGenerators`	Observable wrapper generation exclusion attribute

IObservablePort Interface

The base interface implemented by all Ports and Adapters. Identifies the request category in the Observability layer through the RequestCategory property.

namespace Functorium.Abstractions.Observabilities;

public interface IObservablePort
{
    string RequestCategory { get; }
}

Property	Type	Description
`RequestCategory`	`string`	Category used in observability logs/metrics (e.g., `"Repository"`, `"ExternalApi"`, `"Messaging"`)

Interface Hierarchy

IObservablePort
├── IRepository<TAggregate, TId>    — Aggregate Root CRUD (Domain Layer)
├── IQueryPort                      — Non-generic marker (Application Layer)
│   └── IQueryPort<TEntity, TDto>   — Specification-based query (Application Layer)
└── (User-defined Port)               — External API, Messaging, etc.

Inheriting IObservablePort enables the [GenerateObservablePort] source generator to auto-generate Tracing, Logging, and Metrics.

Repository Contract (IRepository<TAggregate, TId>)

A persistence contract at the Aggregate Root level. Generic constraints enforce Aggregate Root-level persistence at compile time.

namespace Functorium.Domains.Repositories;

public interface IRepository<TAggregate, TId> : IObservablePort
    where TAggregate : AggregateRoot<TId>
    where TId : struct, IEntityId<TId>
{
    FinT<IO, TAggregate> Create(TAggregate aggregate);
    FinT<IO, TAggregate> GetById(TId id);
    FinT<IO, TAggregate> Update(TAggregate aggregate);
    FinT<IO, int> Delete(TId id);

    FinT<IO, Seq<TAggregate>> CreateRange(IReadOnlyList<TAggregate> aggregates);
    FinT<IO, Seq<TAggregate>> GetByIds(IReadOnlyList<TId> ids);
    FinT<IO, Seq<TAggregate>> UpdateRange(IReadOnlyList<TAggregate> aggregates);
    FinT<IO, int> DeleteRange(IReadOnlyList<TId> ids);
}

Generic Constraints

Type Parameter	Constraint	Description
`TAggregate`	`AggregateRoot<TId>`	Only Aggregate Roots can be Repository targets (prevents direct Entity persistence)
`TId`	`struct, IEntityId<TId>`	Ulid-based EntityId implementation type

Methods

Method	Return Type	Description
`Create(aggregate)`	`FinT<IO, TAggregate>`	Creates a single Aggregate
`GetById(id)`	`FinT<IO, TAggregate>`	Retrieves an Aggregate by ID (`NotFound` error if absent)
`Update(aggregate)`	`FinT<IO, TAggregate>`	Updates a single Aggregate
`Delete(id)`	`FinT<IO, int>`	Deletes an Aggregate by ID (returns deleted count)
`CreateRange(aggregates)`	`FinT<IO, Seq<TAggregate>>`	Batch creation
`GetByIds(ids)`	`FinT<IO, Seq<TAggregate>>`	Batch retrieval (`PartialNotFound` error if some are missing)
`UpdateRange(aggregates)`	`FinT<IO, Seq<TAggregate>>`	Batch update
`DeleteRange(ids)`	`FinT<IO, int>`	Batch deletion (returns deleted count)

All methods return FinT<IO, T>. Success is expressed as Fin.Succ(value), and failure is expressed as domain/adapter errors.

QueryPort Contract (IQueryPort<TEntity, TDto>)

A read-only port for Specification-based queries and direct DTO returns. Corresponds to the Read model in CQRS.

IQueryPort (Non-generic Marker)

namespace Functorium.Applications.Queries;

public interface IQueryPort : IObservablePort { }

A non-generic marker interface used for runtime type checking, DI scanning, and generic constraints.

IQueryPort<TEntity, TDto>

public interface IQueryPort<TEntity, TDto> : IQueryPort
{
    FinT<IO, PagedResult<TDto>> Search(
        Specification<TEntity> spec,
        PageRequest page,
        SortExpression sort);

    FinT<IO, CursorPagedResult<TDto>> SearchByCursor(
        Specification<TEntity> spec,
        CursorPageRequest cursor,
        SortExpression sort);

    IAsyncEnumerable<TDto> Stream(
        Specification<TEntity> spec,
        SortExpression sort,
        CancellationToken cancellationToken = default);
}

Method	Return Type	Description
`Search(spec, page, sort)`	`FinT<IO, PagedResult<TDto>>`	Offset-based pagination search
`SearchByCursor(spec, cursor, sort)`	`FinT<IO, CursorPagedResult<TDto>>`	Keyset(Cursor)-based pagination search. O(1) performance for deep pages
`Stream(spec, sort, ct)`	`IAsyncEnumerable<TDto>`	Streaming query for large data. Yields without loading everything into memory

Generic Parameters

Type Parameter	Description
`TEntity`	Domain entity type (Specification target)
`TDto`	Return DTO type (directly returned to presentation layer)

Pagination Types

PageRequest

An offset-based pagination request. This is an Application-level query concern, not a domain invariant.

namespace Functorium.Applications.Queries;

public sealed record PageRequest
{
    public const int DefaultPageSize = 20;
    public const int MaxPageSize = 10_000;

    public int Page { get; }
    public int PageSize { get; }
    public int Skip => (Page - 1) * PageSize;

    public PageRequest(int page = 1, int pageSize = DefaultPageSize);
}

Property/Constant	Type	Description
`DefaultPageSize`	`int`	Default page size (`20`)
`MaxPageSize`	`int`	Maximum page size (`10,000`)
`Page`	`int`	Current page number (corrected to `1` if less than 1)
`PageSize`	`int`	Page size (corrected to `DefaultPageSize` if less than 1, capped at `MaxPageSize`)
`Skip`	`int`	Number of items to skip (computed property: `(Page - 1) * PageSize`)

PagedResult<T>

An offset-based pagination result container.

public sealed record PagedResult<T>(
    IReadOnlyList<T> Items,
    int TotalCount,
    int Page,
    int PageSize)
{
    public int TotalPages => (int)Math.Ceiling((double)TotalCount / PageSize);
    public bool HasPreviousPage => Page > 1;
    public bool HasNextPage => Page < TotalPages;
}

Property	Type	Description
`Items`	`IReadOnlyList<T>`	List of items for the current page
`TotalCount`	`int`	Total number of items
`Page`	`int`	Current page number
`PageSize`	`int`	Page size
`TotalPages`	`int`	Total number of pages (computed property)
`HasPreviousPage`	`bool`	Whether a previous page exists
`HasNextPage`	`bool`	Whether a next page exists

CursorPageRequest

A keyset(cursor)-based pagination request. Provides O(1) performance for deep pages compared to offset-based pagination.

public sealed record CursorPageRequest
{
    public const int DefaultPageSize = 20;
    public const int MaxPageSize = 10_000;

    public string? After { get; }
    public string? Before { get; }
    public int PageSize { get; }

    public CursorPageRequest(
        string? after = null,
        string? before = null,
        int pageSize = DefaultPageSize);
}

Property/Constant	Type	Description
`DefaultPageSize`	`int`	Default page size (`20`)
`MaxPageSize`	`int`	Maximum page size (`10,000`)
`After`	`string?`	Retrieve items after this cursor (forward pagination)
`Before`	`string?`	Retrieve items before this cursor (backward pagination)
`PageSize`	`int`	Page size (corrected to `DefaultPageSize` if less than 1, capped at `MaxPageSize`)

CursorPagedResult<T>

A keyset(cursor)-based pagination result container.

public sealed record CursorPagedResult<T>(
    IReadOnlyList<T> Items,
    string? NextCursor,
    string? PrevCursor,
    bool HasMore);

Property	Type	Description
`Items`	`IReadOnlyList<T>`	List of items for the current page
`NextCursor`	`string?`	Next page cursor (`null` if no more items)
`PrevCursor`	`string?`	Previous page cursor
`HasMore`	`bool`	Whether more pages exist

SortExpression

A multi-field sort expression. Combines sort conditions via Fluent API.

public sealed class SortExpression
{
    public Seq<SortField> Fields { get; }
    public bool IsEmpty { get; }

    public static SortExpression Empty { get; }
    public static SortExpression By(string fieldName);
    public static SortExpression By(string fieldName, SortDirection direction);
    public SortExpression ThenBy(string fieldName);
    public SortExpression ThenBy(string fieldName, SortDirection direction);
}

Member	Type	Description
`Fields`	`Seq<SortField>`	List of sort fields (applied in order)
`IsEmpty`	`bool`	Whether sort conditions are empty
`Empty`	`SortExpression`	No sorting (static property)
`By(fieldName)`	`SortExpression`	Creates single field ascending sort (static factory)
`By(fieldName, direction)`	`SortExpression`	Creates single field + direction sort (static factory)
`ThenBy(fieldName)`	`SortExpression`	Chains additional sort field (ascending)
`ThenBy(fieldName, direction)`	`SortExpression`	Chains additional sort field + direction

SortField

A pair of sort field and direction.

public sealed record SortField(string FieldName, SortDirection Direction);

Property	Type	Description
`FieldName`	`string`	Field name to sort by
`Direction`	`SortDirection`	Sort direction

SortDirection

A SmartEnum representing sort direction.

public sealed class SortDirection : SmartEnum<SortDirection, string>
{
    public static readonly SortDirection Ascending;   // Value: "asc"
    public static readonly SortDirection Descending;  // Value: "desc"

    public static SortDirection Parse(string? value);
}

Member	Value	Description
`Ascending`	`"asc"`	Ascending order
`Descending`	`"desc"`	Descending order
`Parse(value)`	-	Parses `"asc"`/`"desc"` case-insensitively. Returns `Ascending` for `null`/empty string

Specification Pattern

Specification<T> (Abstract Base Class)

An abstract base class that encapsulates domain conditions and supports And/Or/Not composition.

namespace Functorium.Domains.Specifications;

public abstract class Specification<T>
{
    public static Specification<T> All { get; }
    public virtual bool IsAll => false;

    public abstract bool IsSatisfiedBy(T entity);

    public Specification<T> And(Specification<T> other);
    public Specification<T> Or(Specification<T> other);
    public Specification<T> Not();

    public static Specification<T> operator &(Specification<T> left, Specification<T> right);
    public static Specification<T> operator |(Specification<T> left, Specification<T> right);
    public static Specification<T> operator !(Specification<T> spec);
}

Member	Type	Description
`All`	`Specification<T>`	Specification satisfied by all entities (Null Object). `All & X = X`
`IsAll`	`bool`	Whether this Specification is the identity element (`All`)
`IsSatisfiedBy(entity)`	`bool`	Checks whether the entity satisfies the condition
`And(other)`	`Specification<T>`	AND composition
`Or(other)`	`Specification<T>`	OR composition
`Not()`	`Specification<T>`	NOT negation

Operator overloading:

Operator	Equivalent Method	Description
`&`	`And()`	AND composition. Includes `All` identity optimization (`All & X = X`)
`\|`	`Or()`	OR composition
`!`	`Not()`	NOT negation

ExpressionSpecification<T>

An Expression Tree-based Specification abstract class. Implementing ToExpression() automatically provides IsSatisfiedBy().

public abstract class ExpressionSpecification<T> : Specification<T>, IExpressionSpec<T>
{
    public abstract Expression<Func<T, bool>> ToExpression();
    public sealed override bool IsSatisfiedBy(T entity);  // Expression compile + caching
}

Member	Description
`ToExpression()`	Returns the condition as `Expression<Func<T, bool>>` (must be implemented by subclass)
`IsSatisfiedBy(entity)`	Compiles and evaluates the Expression. Compiled delegate is cached (`sealed`)

IExpressionSpec<T>

An interface indicating that a Specification can provide an Expression Tree. Used by LINQ providers such as EF Core for automatic SQL translation.

namespace Functorium.Domains.Specifications;

public interface IExpressionSpec<T>
{
    Expression<Func<T, bool>> ToExpression();
}

PropertyMap<TEntity, TModel>

Property mapping for auto-converting Entity Expression to Model Expression. Used in EfCoreRepositoryBase’s BuildQuery() method for Specification to SQL conversion.

namespace Functorium.Domains.Specifications.Expressions;

public sealed class PropertyMap<TEntity, TModel>
{
    public PropertyMap<TEntity, TModel> Map<TValue, TModelValue>(
        Expression<Func<TEntity, TValue>> entityProp,
        Expression<Func<TModel, TModelValue>> modelProp);

    public string? TranslateFieldName(string entityFieldName);
    public Expression<Func<TModel, bool>> Translate(Expression<Func<TEntity, bool>> expression);
}

Method	Return Type	Description
`Map(entityProp, modelProp)`	`PropertyMap<TEntity, TModel>`	Registers Entity-Model property mapping. Fluent API
`TranslateFieldName(name)`	`string?`	Translates Entity field name to Model field name (`null` if no mapping)
`Translate(expression)`	`Expression<Func<TModel, bool>>`	Converts Entity Expression to Model Expression

Supported Entity property expressions:

Form	Example
Direct member access	`p => p.Name`
Type conversion	`p => (decimal)p.Price`
`ToString()` call	`p => p.Id.ToString()`

SpecificationExpressionResolver

A utility that extracts Expression Trees from Specifications and recursively composes And/Or/Not combinations.

namespace Functorium.Domains.Specifications.Expressions;

public static class SpecificationExpressionResolver
{
    public static Expression<Func<T, bool>>? TryResolve<T>(Specification<T> spec);
}

Method	Return Type	Description
`TryResolve(spec)`	`Expression<Func<T, bool>>?`	Extracts Expression from Specification. Direct extraction for `IExpressionSpec` implementations, recursive composition for And/Or/Not combinations. Returns `null` if unsupported

Implementation Base Classes

EfCoreRepositoryBase<TAggregate, TId, TModel>

Common base class for EF Core Repositories. Includes declared in the constructor are automatically applied to all read queries through ReadQuery(), structurally preventing N+1 problems.

namespace Functorium.Adapters.Repositories;

public abstract class EfCoreRepositoryBase<TAggregate, TId, TModel>
    : IRepository<TAggregate, TId>
    where TAggregate : AggregateRoot<TId>
    where TId : struct, IEntityId<TId>
    where TModel : class, IHasStringId
{
    protected EfCoreRepositoryBase(
        IDomainEventCollector eventCollector,
        Func<IQueryable<TModel>, IQueryable<TModel>>? applyIncludes = null,
        PropertyMap<TAggregate, TModel>? propertyMap = null);
}

Generic Constraints

Type Parameter	Constraint	Description
`TAggregate`	`AggregateRoot<TId>`	Aggregate Root type
`TId`	`struct, IEntityId<TId>`	Ulid-based EntityId type
`TModel`	`class, IHasStringId`	EF Core entity model (string Id required)

Constructor Parameters

Parameter	Type	Description
`eventCollector`	`IDomainEventCollector`	Domain event collector
`applyIncludes`	`Func<IQueryable<TModel>, IQueryable<TModel>>?`	Navigation Property Include declaration (N+1 prevention). No Includes if `null`
`propertyMap`	`PropertyMap<TAggregate, TModel>?`	Mapping for Specification to Model Expression conversion. Required when using `BuildQuery`/`ExistsBySpec`

Required Subclass Implementation

Member	Type	Description
`DbContext`	`DbContext`	EF Core DbContext (abstract property)
`DbSet`	`DbSet<TModel>`	Entity model’s DbSet (abstract property)
`ToDomain(model)`	`TAggregate`	Model to Domain mapping (abstract method)
`ToModel(aggregate)`	`TModel`	Domain to Model mapping (abstract method)

Protected Infrastructure Members

Member	Type	Description
`EventCollector`	`IDomainEventCollector`	Domain event collector
`PropertyMap`	`PropertyMap<TAggregate, TModel>?`	Specification to Model property mapping
`IdBatchSize`	`int` (virtual, default `500`)	Batch size for preventing SQL IN clause parameter limit
`ReadQuery()`	`IQueryable<TModel>`	Read-only query with Includes auto-applied (`AsNoTracking`)
`ReadQueryIgnoringFilters()`	`IQueryable<TModel>`	Read query with Includes + global filter bypass (for Soft Delete queries)
`BuildQuery(spec)`	`Fin<IQueryable<TModel>>`	Specification to Model Expression query builder (PropertyMap required)
`ExistsBySpec(spec)`	`FinT<IO, bool>`	Specification-based existence check (PropertyMap required)
`ByIdPredicate(id)`	`Expression<Func<TModel, bool>>`	Single ID matching Expression (virtual, default `IHasStringId`-based implementation)
`ByIdsPredicate(ids)`	`Expression<Func<TModel, bool>>`	Multiple ID matching Expression (virtual, default `IHasStringId`-based implementation)

Error Helpers

Method	Description
`NotFoundError(id)`	Creates `AdapterErrorType.NotFound` error. Actual subclass name is included in the error code
`PartialNotFoundError(requestedIds, foundAggregates)`	Creates `AdapterErrorType.PartialNotFound` error. Includes list of missing IDs
`NotConfiguredError(message)`	Creates `AdapterErrorType.NotConfigured` error
`NotSupportedError(currentValue, message)`	Creates `AdapterErrorType.NotSupported` error

IHasStringId

String Id interface that EF Core models must implement. Provides default implementation for EfCoreRepositoryBase’s ByIdPredicate/ByIdsPredicate.

namespace Functorium.Adapters.Repositories;

public interface IHasStringId
{
    string Id { get; set; }
}

InMemoryRepositoryBase<TAggregate, TId>

Common base class for InMemory Repositories. Provides default implementation of full IRepository CRUD based on ConcurrentDictionary.

namespace Functorium.Adapters.Repositories;

public abstract class InMemoryRepositoryBase<TAggregate, TId>
    : IRepository<TAggregate, TId>
    where TAggregate : AggregateRoot<TId>
    where TId : struct, IEntityId<TId>
{
    protected InMemoryRepositoryBase(IDomainEventCollector eventCollector);
}

Required Subclass Implementation

Member	Type	Description
`Store`	`ConcurrentDictionary<TId, TAggregate>`	In-memory store (abstract property). Subclass provides a static instance

Protected Members

Member	Type	Description
`EventCollector`	`IDomainEventCollector`	Domain event collector
`RequestCategory`	`string` (virtual, default `"Repository"`)	Observability category

DapperQueryBase<TEntity, TDto>

Common infrastructure for Dapper-based QueryAdapters. Subclasses are responsible only for SQL declaration and WHERE building.

namespace Functorium.Adapters.Repositories;

public abstract class DapperQueryBase<TEntity, TDto>
{
    protected DapperQueryBase(IDbConnection connection);
    protected DapperQueryBase(
        IDbConnection connection,
        DapperSpecTranslator<TEntity> translator,
        string tableAlias = "");
}

Required Subclass Implementation

Member	Type	Description
`SelectSql`	`string`	SELECT query (up to FROM + JOIN, excluding WHERE)
`CountSql`	`string`	COUNT query (up to FROM + JOIN, excluding WHERE)
`DefaultOrderBy`	`string`	Default ORDER BY clause (e.g., `"p.created_at DESC"`)
`AllowedSortColumns`	`Dictionary<string, string>`	Allowed sort column mapping (DTO field name to DB column name)

Protected Methods

Method	Description
`BuildWhereClause(spec)`	Specification to SQL WHERE clause conversion. Default implementation provided when `DapperSpecTranslator` is injected. Otherwise, subclass override is required
`PaginationClause`	DB dialect-specific Offset pagination clause (virtual, default `"LIMIT @PageSize OFFSET @Skip"`)
`CursorPaginationClause`	DB dialect-specific Keyset pagination clause (virtual, default `"LIMIT @PageSize"`)
`GetCursorValue(item, fieldName)`	Extract cursor value from DTO (virtual, Reflection-based default implementation + caching)
`Params(values)`	`DynamicParameters` creation helper (static method)

Public Methods

Method	Return Type	Description
`Search(spec, page, sort)`	`FinT<IO, PagedResult<TDto>>`	Offset-based pagination search (COUNT + SELECT multi-query)
`SearchByCursor(spec, cursor, sort)`	`FinT<IO, CursorPagedResult<TDto>>`	Keyset-based search (`PageSize + 1` strategy for HasMore determination)
`Stream(spec, sort, ct)`	`IAsyncEnumerable<TDto>`	Streaming query via `QueryUnbufferedAsync` (`DbConnection` required)

InMemoryQueryBase<TEntity, TDto>

Common infrastructure for InMemory-based QueryAdapters. InMemory counterpart base class for DapperQueryBase.

namespace Functorium.Adapters.Repositories;

public abstract class InMemoryQueryBase<TEntity, TDto>
{
    // (No constructor parameters)
}

Required Subclass Implementation

Member	Type	Description
`DefaultSortField`	`string`	Default sort field name
`GetProjectedItems(spec)`	`IEnumerable<TDto>`	Filtering + DTO projection (including JOIN logic)
`SortSelector(fieldName)`	`Func<TDto, object>`	Sort key selector (field name to selector function)

Public Methods

Method	Return Type	Description
`Search(spec, page, sort)`	`FinT<IO, PagedResult<TDto>>`	Offset-based pagination search
`SearchByCursor(spec, cursor, sort)`	`FinT<IO, CursorPagedResult<TDto>>`	Keyset-based search
`Stream(spec, sort, ct)`	`IAsyncEnumerable<TDto>`	In-memory streaming query

DapperSpecTranslator<TEntity>

A registry that translates Specifications to SQL WHERE clauses. Once configured per entity type, multiple Dapper adapters can share it with different table aliases.

namespace Functorium.Adapters.Repositories;

public sealed class DapperSpecTranslator<TEntity>
{
    public DapperSpecTranslator<TEntity> WhenAll(
        Func<string, (string Where, DynamicParameters Params)> handler);

    public DapperSpecTranslator<TEntity> When<TSpec>(
        Func<TSpec, string, (string Where, DynamicParameters Params)> handler)
        where TSpec : Specification<TEntity>;

    public (string Where, DynamicParameters Params) Translate(
        Specification<TEntity> spec, string tableAlias = "");

    public static DynamicParameters Params(params (string Name, object Value)[] values);
    public static string Prefix(string tableAlias);
}

Method	Return Type	Description
`WhenAll(handler)`	`DapperSpecTranslator<TEntity>`	Register `IsAll` (identity) Specification handler (Fluent API)
`When<TSpec>(handler)`	`DapperSpecTranslator<TEntity>`	Register SQL translation handler for a specific Specification type (Fluent API)
`Translate(spec, alias)`	`(string Where, DynamicParameters Params)`	Translates Specification to SQL WHERE clause
`Params(values)`	`DynamicParameters`	`DynamicParameters` creation helper (static)
`Prefix(tableAlias)`	`string`	Returns table alias prefix (e.g., `"p"` to `"p."`, `""` to `""`)

DI Registration (ObservablePortRegistration)

A collection of IServiceCollection extension methods for registering IObservablePort implementations in the DI container. Uses ActivatorUtilities.CreateInstance to auto-inject ActivitySource, ILogger, and IMeterFactory into implementation type constructors.

namespace Functorium.Abstractions.Registrations;

public static class ObservablePortRegistration
{
    // Single interface registration
    public static IServiceCollection RegisterScopedObservablePort<TService, TImpl>(...);
    public static IServiceCollection RegisterTransientObservablePort<TService, TImpl>(...);
    public static IServiceCollection RegisterSingletonObservablePort<TService, TImpl>(...);

    // Multiple interfaces to single implementation registration (For suffix)
    public static IServiceCollection RegisterScopedObservablePortFor<T1, T2, TImpl>(...);
    public static IServiceCollection RegisterScopedObservablePortFor<T1, T2, T3, TImpl>(...);
    public static IServiceCollection RegisterScopedObservablePortFor<TImpl>(
        ..., params Type[] serviceTypes);

    public static IServiceCollection RegisterTransientObservablePortFor<T1, T2, TImpl>(...);
    public static IServiceCollection RegisterTransientObservablePortFor<T1, T2, T3, TImpl>(...);
    public static IServiceCollection RegisterTransientObservablePortFor<TImpl>(
        ..., params Type[] serviceTypes);

    public static IServiceCollection RegisterSingletonObservablePortFor<T1, T2, TImpl>(...);
    public static IServiceCollection RegisterSingletonObservablePortFor<T1, T2, T3, TImpl>(...);
    public static IServiceCollection RegisterSingletonObservablePortFor<TImpl>(
        ..., params Type[] serviceTypes);
}

Naming Conventions

Pattern	Description
`Register{Lifetime}ObservablePort<TService, TImpl>`	Register a single interface with one implementation
`Register{Lifetime}ObservablePortFor<T1, T2, TImpl>`	Register 2 interfaces with one implementation
`Register{Lifetime}ObservablePortFor<T1, T2, T3, TImpl>`	Register 3 interfaces with one implementation
`Register{Lifetime}ObservablePortFor<TImpl>(params Type[])`	Register N interfaces with one implementation (4 or more)

Supported Lifetimes

Lifetime	Instance sharing scope
`Scoped`	One instance per HTTP request
`Transient`	New instance per request
`Singleton`	One instance for the entire application

Generic Constraints

All service interface type parameters have the class, IObservablePort constraint. The params Type[] overload validates IObservablePort implementation and interface implementation of the implementation class at runtime.

For Suffix Behavior

Methods with the For suffix first register the implementation, then register each service interface to reference the same instance via GetRequiredService<TImplementation>(). This enables resolving a single implementation through multiple interfaces.

// Usage example: Register IProductRepository and IProductQuery with the same Observable implementation
services.RegisterScopedObservablePortFor<IProductRepository, IProductQuery, ProductObservable>();

Options Configuration (OptionsConfigurator)

A utility for registering FluentValidation-based options validation in DI.

namespace Functorium.Adapters.Abstractions.Options;

public static class OptionsConfigurator
{
    public static OptionsBuilder<TOptions> RegisterConfigureOptions<TOptions, TValidator>(
        this IServiceCollection services,
        string configurationSectionName)
        where TOptions : class
        where TValidator : class, IValidator<TOptions>;
}

RegisterConfigureOptions Behavior

Order	Behavior	Description
1	`IValidator<TOptions>` registration	Registers `TValidator` as Scoped in DI
2	`BindConfiguration`	Binds the `configurationSectionName` section of `appsettings.json` to `TOptions`
3	FluentValidation connection	Connects FluentValidation validation through `IValidateOptions<TOptions>` implementation
4	`ValidateOnStart`	Run options validation at program startup
5	`IStartupOptionsLogger` auto-registration	If `TOptions` implements `IStartupOptionsLogger`, auto-registers for options value logging at startup

// Usage example
services.RegisterConfigureOptions<DatabaseOptions, DatabaseOptionsValidator>("Database");

Source Generator Attributes

[GenerateObservablePort]

Applying this attribute to an Adapter class causes the source generator to automatically generate an Observable wrapper class. The generated Observable provides OpenTelemetry-based Tracing, Logging, and Metrics.

namespace Functorium.Adapters.SourceGenerators;

[AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = false)]
public sealed class GenerateObservablePortAttribute : Attribute;

Property	Value	Description
`AttributeTargets`	`Class`	Can only be applied to classes
`AllowMultiple`	`false`	Applied only once per class
`Inherited`	`false`	Not inherited by derived classes

Prerequisites:

The project must reference the Functorium.SourceGenerators package
Interface methods in the Adapter class require the virtual keyword (Pipeline overrides)

// Usage example
[GenerateObservablePort]
public class ProductRepositoryInMemory
    : InMemoryRepositoryBase<Product, ProductId>, IProductRepository
{
    // virtual methods...
}
// -> ProductRepositoryInMemoryObservable class is auto-generated

[ObservablePortIgnore]

An attribute that excludes a specific method from Observable wrapper generation. Used for helper methods or internal methods where observability is unnecessary.

namespace Functorium.Adapters.SourceGenerators;

[AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
public sealed class ObservablePortIgnoreAttribute : Attribute;

Property	Value	Description
`AttributeTargets`	`Method`	Can only be applied to methods
`AllowMultiple`	`false`	Applied only once per method
`Inherited`	`false`	Not inherited by derived classes

// Usage example
[GenerateObservablePort]
public class ProductRepository : InMemoryRepositoryBase<Product, ProductId>, IProductRepository
{
    [ObservablePortIgnore]
    public virtual FinT<IO, int> GetCount() => ...;  // Excluded from Observable wrapper
}

Document	Description
Port Architecture and Definitions	Port design principles, interface definition pattern guide by type
Adapter Implementation	Repository, External API, Query Adapter implementation guide by type
Adapter Pipeline and DI Registration	Observable Pipeline creation and DI registration guide
Adapter Testing	Adapter unit/integration testing guide
Entity and Aggregate Specification	`AggregateRoot<TId>`, `IEntityId<TId>` API specification
Error System Specification	`AdapterErrorType` (NotFound, PartialNotFound, etc.) API specification
Observability Specification	3-Pillar field/tag specification, Meter definition rules
Source Generator Specification	`ObservablePortGenerator` source generator detailed specification

Port and Adapter Specification

Summary

Key Types

IObservablePort Interface

Interface Hierarchy

Repository Contract (IRepository<TAggregate, TId>)

Generic Constraints

Methods

QueryPort Contract (IQueryPort<TEntity, TDto>)

IQueryPort (Non-generic Marker)

IQueryPort<TEntity, TDto>

Generic Parameters

Pagination Types

PageRequest

PagedResult<T>

CursorPageRequest

CursorPagedResult<T>

SortExpression

SortField

SortDirection

Specification Pattern

Specification<T> (Abstract Base Class)

ExpressionSpecification<T>

IExpressionSpec<T>

PropertyMap<TEntity, TModel>

SpecificationExpressionResolver

Implementation Base Classes

EfCoreRepositoryBase<TAggregate, TId, TModel>

Generic Constraints

Constructor Parameters

Required Subclass Implementation

Protected Infrastructure Members

Error Helpers

IHasStringId

InMemoryRepositoryBase<TAggregate, TId>

Required Subclass Implementation

Protected Members

DapperQueryBase<TEntity, TDto>

Required Subclass Implementation

Protected Methods

Public Methods

InMemoryQueryBase<TEntity, TDto>

Required Subclass Implementation

Public Methods

DapperSpecTranslator<TEntity>

DI Registration (ObservablePortRegistration)

Naming Conventions

Supported Lifetimes

Generic Constraints

For Suffix Behavior

Options Configuration (OptionsConfigurator)

RegisterConfigureOptions Behavior

Source Generator Attributes

[GenerateObservablePort]

[ObservablePortIgnore]

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