Arch Lens Repository Access

Repository/Data Access Architecture Lens

Cognitive Mode: Data-Centric Primary Question: "How is data accessed?" Focus: Repository Pattern, Entity Relationships, Query Patterns, Format Conversion

When to Use

• Need to understand data access layer architecture
• Documenting repository pattern implementation
• Analyzing entity relationships and query patterns
• User invokes /arch-lens-repository-access or /make-arch-diag repository

Critical Constraints

NEVER:

• Modify any source code files
• Focus on data flow (that's data lineage lens)
• Include business logic details

ALWAYS:

• Focus on REPOSITORIES and their methods
• Show entity relationships (1:1, 1:N, N:N)
• Document key query patterns
• Identify format conversion boundaries
• BEFORE creating any diagram, LOAD the /mermaid skill using the Skill tool - this is MANDATORY

---

Analysis Workflow

Step 1: Launch Parallel Exploration Subagents

Spawn Explore subagents to investigate:

Repository Classes

• Find all repository implementations
• Identify base repository patterns
• Look for: Repository classes, DAO (Data Access Object) patterns, base repository abstractions

Entity Models

• Find entity/model classes
• Identify table/collection definitions
• Look for: ORM models (ActiveRecord, Entity Framework, TypeORM, etc.), data models, entity classes

CRUD Operations

• Find standard CRUD methods
• Identify specialized query methods
• Look for: create, get, update, delete, save, find, getby_, query methods

Query Patterns

• Find complex queries and joins
• Identify index usage patterns
• Look for: filter, where, join, orderby, groupby, query builders

Factory/Scoping

• Find repository factory patterns
• Identify scope management
• Look for: Factory patterns, dependency injection, session/context management

Format Conversion

• Find adapter/converter patterns
• Identify boundary conversions
• Look for: Adapters, DTOs, to/from methods, serializers, mappers

Step 2: Map Entity Relationships

Document:

• Entities: All model classes
• Relationships: Foreign key relationships, cardinality
• Key Fields: Primary keys, business keys
• Repositories: Which repo manages which entity

CRITICAL - Analyze Read/Write Direction: For EVERY repository method and data access:

• Read methods: get_*, find_*, query_* - data flows OUT of storage
• Write methods: save_*, create_*, update_*, delete_* - data flows INTO storage
• Bulk operations: Direction of each operation in batch

For EVERY caller-to-repository relationship:

• Does the caller READ from this repository?
• Does the caller WRITE to this repository?
• Or both?

Label connections accordingly (reads, writes, reads/writes)

Step 3: Document Access Patterns

| Pattern | Repository Method | Use Case | |---------|------------------|----------| | By ID | getbyid() | Single entity lookup | | By Business Key | getby | Domain-specific lookup | | List | getall(), getfor | Collection queries | | Bulk | savemany() | Batch operations |

Step 4: Create the Diagram

Use flowchart with:

Direction: LR (left-to-right) for caller-to-storage flow

Subgraphs:

• Callers (who uses repositories)
• Factory (repository construction)
• Repositories by Category
• Conversion (format boundaries)
• Storage (database tables)

Node Styling:

• cli class: Callers (nodes, handlers)
• phase class: Factory, scoping
• newComponent class: Repositories (green to highlight)
• handler class: Conversion adapters
• integration class: Database storage

Show Relationships:

• Entity relationships with cardinality (1:N)
• Repository-to-table mapping
• Conversion flow

Step 5: Write Output

Write the diagram to: temp/arch-lens-repository-access/arch_diag_repository_access_{YYYY-MM-DD_HHMMSS}.md

---

Output Template

# Repository/Data Access Diagram: {System Name}

**Lens:** Repository/Data Access (Data-Centric)
**Question:** How is data accessed?
**Date:** {YYYY-MM-DD}
**Scope:** {What was analyzed}

## Repository Overview

| Category | Count | Key Repositories |
|----------|-------|------------------|
| {category} | {N} | {names} |

## Data Access Diagram

```mermaid
%%{init: {'flowchart': {'nodeSpacing': 50, 'rankSpacing': 60, 'curve': 'basis'}}}%%
flowchart LR
    %% CLASS DEFINITIONS %%
    classDef cli fill:#1a237e,stroke:#7986cb,stroke-width:2px,color:#fff;
    classDef stateNode fill:#004d40,stroke:#4db6ac,stroke-width:2px,color:#fff;
    classDef handler fill:#e65100,stroke:#ffb74d,stroke-width:2px,color:#fff;
    classDef phase fill:#6a1b9a,stroke:#ba68c8,stroke-width:2px,color:#fff;
    classDef output fill:#00695c,stroke:#4db6ac,stroke-width:2px,color:#fff;
    classDef integration fill:#c62828,stroke:#ef9a9a,stroke-width:2px,color:#fff;
    classDef newComponent fill:#2e7d32,stroke:#81c784,stroke-width:2px,color:#fff;

    subgraph Callers ["CALLERS"]
        CALLER1["Handler/Service━━━━━━━━━━Business logic"]
    end

    subgraph Factory ["REPOSITORY FACTORY"]
        direction TB
        FAC["RepositoryFactory━━━━━━━━━━Dependency injection"]
        SCOPE["Scoping━━━━━━━━━━Context management"]
    end

    subgraph Repositories ["REPOSITORIES"]
        direction TB
        REPO1["EntityRepository━━━━━━━━━━CRUD methods"]
        BASE["BaseRepository━━━━━━━━━━Generic CRUD"]
    end

    subgraph Conversion ["FORMAT CONVERSION"]
        direction TB
        ADAPTER["Adapters/DTOs━━━━━━━━━━Serialization"]
    end

    subgraph Storage ["DATABASE"]
        direction TB
        DB[("Table/Collection━━━━━━━━━━Persistent storage")]
    end

    %% FLOW %%
    CALLER1 --> FAC
    FAC --> SCOPE
    SCOPE --> REPO1
    BASE --> REPO1
    REPO1 --> ADAPTER
    ADAPTER --> DB

    %% CLASS ASSIGNMENTS %%
    class CALLER1 cli;
    class FAC,SCOPE phase;
    class REPO1 newComponent;
    class BASE stateNode;
    class ADAPTER handler;
    class DB integration;

Color Legend: | Color | Category | Description | |-------|----------|-------------| | Dark Blue | Callers | Services/handlers that use repositories | | Purple | Factory | Repository construction and scoping | | Green | Repositories | Repository implementations | | Teal | Base | Generic base repository | | Orange | Conversion | Format adapters/DTOs | | Red | Storage | Database tables/collections |

Repository Categories

| Category | Count | Key Repositories | |----------|-------|------------------| | {category} | {N} | {list} |

Key Query Patterns

| Pattern | Repository Method | Use Case | |---------|------------------|----------| | {pattern} | {method} | {use case} |

Entity Relationships

| Parent | Child | Cardinality | FK | |--------|-------|-------------|-----| | {parent} | {child} | {1:N/1:1} | {fk field} |

---

## Pre-Diagram Checklist

Before creating the diagram, verify:

- [ ] LOADED `/mermaid` skill using the Skill tool
- [ ] Using ONLY classDef styles from the mermaid skill (no invented colors)
- [ ] Diagram will include a color legend table

---

## Related Skills

- `/make-arch-diag` - Parent skill for lens selection
- `/mermaid` - MUST BE LOADED before creating diagram
- `/arch-lens-data-lineage` - For data flow view
- `/arch-lens-c4-container` - For storage container view

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [Trecek](https://github.com/Trecek)
- **Source:** [Trecek/useful-claude-skills](https://github.com/Trecek/useful-claude-skills)
- **License:** MIT

Install and usage instructions live in the source repository linked above.