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Common Helpers

Serenity provides a set of small static helper classes in the Serenity namespace for common operations. They're used throughout the framework and are available to your application code. This page gives a brief overview — see the API reference for the full member lists.

StringHelper

StringHelper contains extension methods that operate on strings. The most commonly used ones:

  • TrimToNull() — trims a string and returns null if the result is empty (used when saving user input to the database).
  • TrimToEmpty() — trims a string and returns "" if the result is empty.
  • IsEmptyOrNull() / IsNullOrEmpty() / IsTrimmedEmpty() — null/empty checks.
  • IsTrimmedSame() — compares two strings ignoring leading/trailing whitespace.
  • ToSingleLine(), RemoveDiacritics(), and other text utilities.

DateHelper

DateHelper contains date utilities and constants:

  • ISODateTimeFormatUTC / ISODateTimeFormatLocal — ISO 8601 format strings.
  • TryParseISO8601DateTime() — parses an ISO 8601 date-time string.
  • CurrentDateElementOrder / DateElementOrderFor() — determines the date element order (dmy, mdy, ymd) for a culture.
  • DateElementOrder enum — the possible date element orders.

EnumMapper

EnumMapper provides cached enum parsing:

  • Parse<TEnum>(string key) — parses an enum key or numeric value.
  • TryParse<TEnum>(string key, out TEnum value) — tries to parse without throwing.
  • ToString(Enum) — converts an enum value to its key.

Invariants

Invariants provides invariant-culture constants and conversion helpers:

  • NumberFormat / DateTimeFormat — invariant culture format info.
  • ToInvariant() — extension methods that convert values (int, long, double, decimal, DateTime, etc.) to strings using the invariant culture.
  • ToDateTime() — parses a string to DateTime using the invariant culture.

These are important for producing culture-independent strings (e.g. for storage or serialization).

CollectionExtensions

CollectionExtensions provides basic collection helpers:

  • AddRange() — adds multiple items to a collection.
  • Get() — dictionary lookup that returns the default value if the key isn't found.

ExceptionExtensions

ExceptionExtensions provides exception helpers:

  • SetData() — sets custom data on the base exception.

UriHelper

UriHelper provides URL helpers:

  • Combine(url, fileName) — combines a URL and a filename by inserting a / (like Path.Combine), rejecting paths containing ...

PathHelper

PathHelper provides secure path helpers:

  • IsSecureRelativePath() / IsSecureRelativeFile() — checks whether a path is a safe relative path (no .., no root, no invalid characters).
  • SecureCombine(root, relativePath) — combines a root and a relative path after validating it.
  • ToUrl() — converts a path to a URL.

These are used by the upload system and other places that handle user-supplied paths.

IServiceResolver

IServiceResolver<TService> is a generic version of IServiceProvider that resolves a service on demand. It's covered in detail in Dependency Injection.

See Also