CoerceExtensions

Purpose

Provides type coercion and conversion helpers implemented in CoerceExtensions.cs. These helpers attempt to convert object values to specified target types using a series of parsing strategies and fallbacks.

When to Use

• When you need a tolerant conversion from loosely-typed values (e.g., deserialized JSON, configuration values) into primitive types or enums.
• When you want a conversion that returns defaults or fallbacks rather than throwing exceptions in common parse-failure scenarios.

Be cautious: these helpers are marked [Obsolete] in source with suggestions to prefer TryParse/Convert.ChangeType and explicit conversion logic for modern code.

API Reference

• object CoerceType(this object value, Type targetType, object defaultValue)
  • Attempts to convert value to targetType, returning defaultValue or a type-appropriate default when conversion fails.
• bool CoerceType<T>(this object value, Type targetType, out object returnValue, Func<Type, object, T> parseFunc, object defaultValue)
  • Attempt conversion using a custom parse function specialized for T.
• bool CoerceType(this object value, Type targetType, out object returnValue, Func<Type, bool> checkFunc, Func<Type, object, object> parseFunc, object defaultValue)
  • Attempt conversion when checkFunc returns true for the target type, using parseFunc to produce returnValue. On exception, falls back to defaultValue or a type default.

How It Works

CoerceType implements layered parsing:

• Special-cases for bool with tolerant parsing accepting "y"/"n".
• Enum parsing using Enum.Parse (case-insensitive).
• Sequential attempts to parse as common primitive types (bool, decimal, long, int, short, byte, char, double, float, DateTime) using Parse methods with invariant culture.
• Fallback to Convert.ChangeType when specific parses fail.
• If all attempts fail, returns the original value or defaultValue depending on overload behavior.

Examples

object s = "42";
var val = s.CoerceType(typeof(int), 0); // returns int 42

object b = "y";
var boolVal = b.CoerceType(typeof(bool), false); // true

object e = "Sunday";
var day = e.CoerceType(typeof(DayOfWeek), DayOfWeek.Monday); // DayOfWeek.Sunday

Remarks

• The code is annotated [Obsolete] — prefer explicit TryParse calls and Convert.ChangeType where possible for clarity and maintainability.
• Culture: parsing uses CultureInfo.InvariantCulture for numeric and DateTime parsing to avoid culture-dependent surprises.
• Enum parsing is case-insensitive.
• CoerceType may return original value if conversions fail; review call sites to ensure this behavior is acceptable.

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This document mirrors the implementation in CoerceExtensions.cs and highlights trade-offs and modern alternatives.