Query Generator

Generate CQRS-compliant Queries and Query Handlers with tests.

Query Characteristics

• Immutable: final readonly class
• Interrogative naming: Get/Find/List + noun
• No side effects: Handler never modifies state
• Returns DTOs: Never returns domain entities
• Read-optimized: Can use dedicated read models

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Generation Process

Step 1: Generate Query

Path: src/Application/{BoundedContext}/Query/

1. {Name}Query.php — Immutable query DTO with parameters

Step 2: Generate Handler

Path: src/Application/{BoundedContext}/Handler/

1. {Name}Handler.php — Read model consumer

Step 3: Generate DTOs

Path: src/Application/{BoundedContext}/DTO/

1. {Name}DTO.php — Result data structure
2. PaginatedResultDTO.php — For list queries (optional)

Step 4: Generate Read Model Interface

Path: src/Application/{BoundedContext}/ReadModel/

1. {Name}ReadModelInterface.php — Query methods contract

Step 5: Generate Tests

Path: tests/Unit/Application/{BoundedContext}/

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File Placement

Component	Path
Query	src/Application/{BoundedContext}/Query/
Handler	src/Application/{BoundedContext}/Handler/
DTO	src/Application/{BoundedContext}/DTO/
Read Model Interface	src/Application/{BoundedContext}/ReadModel/
Unit Tests	tests/Unit/Application/{BoundedContext}/

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Query Naming Conventions

Purpose	Query Name	Returns
Single by ID	GetOrderDetailsQuery	DTO or throws
Single by field	FindUserByEmailQuery	DTO or null
List/Collection	ListOrdersQuery	PaginatedResult
Search	SearchProductsQuery	array of DTOs
Count	CountPendingOrdersQuery	int
Check existence	CheckEmailExistsQuery	bool

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Quick Template Reference

Query

final readonly class {Name}Query
{
    public function __construct(
        public {IdType} $id
    ) {}
}

Query with Pagination

final readonly class List{Name}Query
{
    public function __construct(
        public ?{FilterType} $filter = null,
        public int $limit = 20,
        public int $offset = 0,
        public string $sortBy = 'created_at',
        public string $sortDirection = 'desc'
    ) {
        if ($limit < 1 || $limit > 100) {
            throw new \InvalidArgumentException('Limit must be between 1 and 100');
        }
    }
}

Handler

final readonly class {Name}Handler
{
    public function __construct(
        private {ReadModelInterface} $readModel
    ) {}

    public function __invoke({Name}Query $query): {ResultDTO}
    {
        $result = $this->readModel->findById($query->id->value);

        if ($result === null) {
            throw new {NotFoundException}($query->id);
        }

        return $result;
    }
}

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Anti-patterns to Avoid

Anti-pattern	Problem	Solution
Side Effects	Handler modifies state	Keep read-only
Returning Entities	Leaking domain	Return DTOs only
No Validation	Invalid parameters	Validate in constructor
Unbounded Lists	Performance issues	Always paginate
Missing Read Model	Querying write model	Use dedicated read model

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References

For complete PHP templates and examples, see:

• references/templates.md — Query, Handler, DTO, PaginatedResult, ReadModel templates
• references/examples.md — GetOrderDetails, ListOrders, OrderDTO examples and tests