Constraints

Constraints are the primary mechanism used by node-rules definitions to validate the contents of a parsed configuration document. They express concrete requirements such as value ranges, allowed formats, uniqueness, or relationships between nodes.

The meaning and applicability of a constraint depend on the declared type of the node it constrains. Some constraints—such as minimum—have different semantics depending on whether they are applied to numbers, text, lists, or other structures. Other constraints are only valid for specific node types.

This chapter documents all available constraints, explains their semantics, and describes which node types they apply to. Each constraint page includes examples and notes to help you choose the correct constraint for your use case.

Common Constraint Rules →

• Common Constraint Rules
  • Rules for Negating Constraints
  • Rules for Custom Constraint Errors
• Minimum and Maximum
  • Type Matrix
  • Rules for Minimum and Maximum
  • Examples
    • Numeric Limits
    • Text Limits
• Equals
  • Type Matrix
  • Rules
  • Examples
    • Numeric Example
    • Alternatives Example
• In
  • Type Matrix
  • Rules
  • Example
• Multiple
  • Type Matrix
  • Rules for Multiple
  • Examples
    • Numeric Constraint
    • Length-Based Constraint
• Matches
  • Type Matrix
  • Rules for Matches
  • Example
• Starts, Ends and Contains
  • Type Matrix
  • Rules for Starts, Ends and Contains
  • Example
• Chars
  • Type Matrix
  • Rules for Chars
• Key
  • Type Matrix
  • Rules for Key
  • Example
• Version
  • Type Matrix
  • Rules for Version Constraints
  • Examples
    • Schema Evolution
    • Good Examples
• The Case Sensitive Flag
  • Rules for the Case Sensitive Flag