Section 2: Active Record: Persistence, Associations & Query Optimization

📄 Lecciones de la Sección

• Lección 1: 2.1 Object-Relational Mapping: Inside Active Record

  Official Guide: Active Record Basics. The complete guide to Object Relational Mapping (ORM) in Rails, Active Record pattern, convention over configuration, CRUD lifecycle, and naming rules.

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• Lección 2: 2.2 Schema Evolution: Migration Fundamentals & Generators

  Official Guide: Active Record Migrations (Part 1). Migration anatomy, generators for standalone changes, adding and removing columns, column data types, table creation, and references.

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• Lección 3: 2.3 Advanced Schema Evolution: Join Tables, Modifiers & Reversibility

  Official Guide: Active Record Migrations (Part 2). Advanced schema operations: join tables, modifying columns, foreign key constraints, composite primary keys, reversible migrations, zero-downtime indexing, and schema dumping.

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• Lección 4: 2.4 Data Integrity: Built-in Validation Helpers & Guardrails

  Official Guide: Active Record Validations (Part 1). The complete reference on model validations: validation triggers, checking validity with valid?, skipping validations, and the catalog of built-in validation helpers.

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• Lección 5: 2.5 Advanced Validations: Conditional Logic, Custom Validators & Errors API

  Official Guide: Active Record Validations (Part 2). Advanced validation patterns: common validation options, strict validations, conditional validations, custom validator classes, and working with the Active Model Errors API.

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• Lección 6: 2.6 Persistence Hooks: Lifecycle Callbacks & Execution Flow

  Official Guide: Active Record Callbacks (Part 1). Deep dive into the Active Record lifecycle: callback registration, available creation/update/destruction callbacks, callback execution, and halting execution.

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• Lección 7: 2.7 Advanced Callbacks: Association Hooks, Callback Classes & Transactions

  Official Guide: Active Record Callbacks (Part 2). Advanced callback mechanics: relational callbacks, association collection hooks, conditional callbacks, reusable callback classes, and transactional commit/rollback hooks.

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• Lección 8: 2.8 Relational Modeling: Core Association Types & Schema Design

  Official Guide: Active Record Associations (Part 1). Master relational data modeling: belongs_to, has_one, has_many, has_many :through, polymorphic associations, self-joins, composite keys, and bi-directional relationships.

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• Lección 9: 2.9 Detailed Association Reference: Options, Extensions, STI & Delegated Types

  Official Guide: Active Record Associations (Part 2). Comprehensive detailed reference: complete options catalog for all association macros, association callbacks, extensions, Single Table Inheritance (STI), and Delegated Types.

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• Lección 10: 2.10 Active Record Querying: Retrieval, Conditions & Aggregations

  Official Guide: Active Record Query Interface (Part 1). Foundational query methods: single record finders, batch iteration with find_each, condition construction (hash, array, NOT, OR, AND), ordering, field projection, and aggregations.

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• Lección 11: 2.11 Advanced Query Optimization: Joins, Eager Loading, Scopes & EXPLAIN

  Official Guide: Active Record Query Interface (Part 2). Advanced query optimization: overriding conditions, table joins, eager loading strategies, strict loading, scope design, dynamic finders, enums, pluck/pick, and analyzing query plans with EXPLAIN.

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• Lección 12: 2.12 Decoupled Logic: Active Model for Non-Persisted Objects

  Official Guide: Active Model Basics. Build rich, tableless Ruby models with Active Model: Model, Attributes, Dirty tracking, Conversions, and Translations.

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