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# Core Validation
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Essential validation functionality providing the main entry points for JSON Schema validation. These functions offer the most convenient ways to validate data against schemas.
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## Capabilities
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### Main Validation Function
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The primary validation function that automatically selects the appropriate validator and validates data against a schema.
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```python { .api }
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def validate(instance, schema, cls=None, *args, **kwargs):
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    """
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    Validate an instance under the given schema.
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    Parameters:
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    - instance: The data to validate
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    - schema: The JSON schema to validate against
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    - cls: Validator class to use (optional, auto-detected from schema)
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    - format_checker: FormatChecker instance for format validation
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    - registry: Schema registry for reference resolution
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    Raises:
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    - ValidationError: If the instance is invalid
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    - SchemaError: If the schema itself is invalid
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    """
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```
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Usage example:
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```python
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from jsonschema import validate, ValidationError
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schema = {"type": "string", "minLength": 5}
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try:
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    validate("hello", schema)  # Valid
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    validate("hi", schema)     # Raises ValidationError
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except ValidationError as e:
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    print(f"Validation failed: {e.message}")
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```
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### Validator Selection
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Automatically determine the appropriate validator class for a given schema based on its $schema keyword.
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```python { .api }
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def validator_for(schema, default=_UNSET):
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    """
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    Retrieve the validator class appropriate for validating the given schema.
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    Parameters:
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    - schema: The schema to analyze
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    - default: Default validator class if $schema not found
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    Returns:
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    - Validator class appropriate for the schema
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    Raises:
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    - SchemaError: If no appropriate validator can be determined
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    """
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```
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Usage example:
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```python
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from jsonschema import validator_for
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# Schema with explicit $schema
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schema = {
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    "$schema": "https://json-schema.org/draft/2020-12/schema",
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    "type": "object",
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    "properties": {"name": {"type": "string"}}
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}
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ValidatorClass = validator_for(schema)
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validator = ValidatorClass(schema)
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# Use the validator
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if validator.is_valid({"name": "John"}):
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    print("Valid!")
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```
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### Quick Validation Check
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Check if data is valid without raising exceptions:
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```python
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from jsonschema import Draft202012Validator
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validator = Draft202012Validator(schema)
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is_valid = validator.is_valid(data)  # Returns boolean
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```
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### Detailed Error Information
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Get all validation errors for comprehensive feedback:
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```python
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from jsonschema import Draft202012Validator
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validator = Draft202012Validator(schema)
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errors = list(validator.iter_errors(data))
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for error in errors:
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    print(f"Error at {'.'.join(str(p) for p in error.path)}: {error.message}")
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```