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JAVASCRIPTHTMLCSSPYTHONSQLJAVACPPCSHARPPHPTYPESCRIPTCRUBYGOSWIFTKOTLINRUSTRBASHSCALAOBJECTIVE-CDARTPERLLUAMATLABXMLJSONMARKDOWNASSEMBLYLATEXYAMLSOLIDITYBLOCKCHAIN

Topics

Introduction to YAML

What is YAMLYAML vs. JSON and XMLYAML Use CasesYAML File Extension

YAML Syntax Basics

YAML IndentationYAML CommentsYAML Key-Value PairsYAML StringsYAML NumbersYAML BooleansYAML Null Values

YAML Data Structures

YAML ListsYAML Nested ListsYAML DictionariesYAML Nested DictionariesYAML Complex Structures

YAML Advanced Features

YAML AnchorsYAML AliasesYAML Merge KeysYAML Block ScalarsYAML Folded ScalarsYAML Literal ScalarsYAML Multi-line Strings

YAML Data Types

YAML TimestampsYAML Binary DataYAML SetsYAML PairsYAML Omap

YAML Document Structure

YAML Multiple DocumentsYAML Document SeparatorsYAML DirectivesYAML Tags

YAML Best Practices

YAML Naming ConventionsYAML Formatting GuidelinesYAML Error HandlingYAML Version Compatibility

Working with YAML

YAML ParsingYAML GenerationYAML ValidationYAML in PythonYAML in RubyYAML in JavaScript

YAML in Configuration

YAML for App ConfigYAML in DockerYAML in KubernetesYAML in Ansible

YAML Security

YAML InjectionYAML Safe LoadingYAML Encryption

YAML Tools and Editors

YAML Online ValidatorsYAML IDE PluginsYAML Command-line Tools

YAML Tags

YAML tags are powerful features that provide explicit type information and custom data handling in YAML documents. They allow users to define and interpret data beyond YAML's basic types.

Purpose of YAML Tags

Tags serve several crucial functions in YAML:

  • Specify data types explicitly
  • Enable custom data representations
  • Facilitate language-specific object serialization
  • Enhance interoperability between different systems

Tag Syntax

YAML tags use the following syntax:

!!tag_name value

The double exclamation marks (!!) indicate a global tag, while a single exclamation mark (!) denotes a local tag.

Common YAML Tags

YAML provides several built-in tags for common data types:

  • !!str: String
  • !!int: Integer
  • !!float: Floating-point number
  • !!bool: Boolean
  • !!null: Null value
  • !!seq: Sequence (list)
  • !!map: Mapping (dictionary)

Examples

Basic Tag Usage

age: !!int "42"
pi: !!float "3.14159"
is_valid: !!bool "true"
names: !!seq
  - Alice
  - Bob
  - Charlie
person: !!map
  name: John Doe
  age: 30

Custom Tags

Users can define custom tags for specific data types or objects:

%TAG !obj! tag:example.com,2023:
---
myObject: !obj!CustomClass
  property1: value1
  property2: value2

Tag Resolution

YAML parsers use tag resolution to determine how to interpret tagged data. This process involves:

  1. Identifying the tag
  2. Locating the corresponding schema
  3. Applying the schema to construct the appropriate data type or object

Best Practices

  • Use tags judiciously to maintain readability
  • Prefer implicit typing when possible
  • Document custom tags thoroughly
  • Ensure tag compatibility across systems

Related Concepts

To deepen your understanding of YAML and its features, explore these related topics:

By mastering YAML tags, you'll enhance your ability to create precise and flexible YAML documents, improving data representation and interoperability in your projects.