Question

How do I convert a DateTime structure to its equivalent RFC 3339 formatted string representation and/or parse this string representation back to a DateTime structure? The RFC-3339 date-time format is used in a number of specifications such as the Atom Syndication Format.

Answer 1

This is an implementation in C# of how to parse and convert a DateTime to and from its RFC-3339 representation. The only restriction it has is that the DateTime is in Coordinated Universal Time (UTC).

using System; using System.Globalization;  namespace DateTimeConsoleApplication {     /// <summary>     /// Provides methods for converting <see cref='DateTime'/> structures to and from the equivalent RFC 3339 string representation.     /// </summary>     public static class Rfc3339DateTime     {         //============================================================         //  Private members         //============================================================         #region Private Members         /// <summary>         /// Private member to hold array of formats that RFC 3339 date-time representations conform to.         /// </summary>         private static string[] formats = new string[0];         /// <summary>         /// Private member to hold the DateTime format string for representing a DateTime in the RFC 3339 format.         /// </summary>         private const string format = 'yyyy-MM-dd'T'HH:mm:ss.fffK';         #endregion          //============================================================         //  Public Properties         //============================================================         #region Rfc3339DateTimeFormat         /// <summary>         /// Gets the custom format specifier that may be used to represent a <see cref='DateTime'/> in the RFC 3339 format.         /// </summary>         /// <value>A <i>DateTime format string</i> that may be used to represent a <see cref='DateTime'/> in the RFC 3339 format.</value>         /// <remarks>         /// <para>         /// This method returns a string representation of a <see cref='DateTime'/> that          /// is precise to the three most significant digits of the seconds fraction; that is, it represents          /// the milliseconds in a date and time value. The <see cref='Rfc3339DateTimeFormat'/> is a valid          /// date-time format string for use in the <see cref='DateTime.ToString(String, IFormatProvider)'/> method.         /// </para>         /// </remarks>         public static string Rfc3339DateTimeFormat         {             get             {                 return format;             }         }         #endregion          #region Rfc3339DateTimePatterns         /// <summary>         /// Gets an array of the expected formats for RFC 3339 date-time string representations.         /// </summary>         /// <value>         /// An array of the expected formats for RFC 3339 date-time string representations          /// that may used in the <see cref='DateTime.TryParseExact(String, string[], IFormatProvider, DateTimeStyles, out DateTime)'/> method.         /// </value>         public static string[] Rfc3339DateTimePatterns         {             get             {                 if (formats.Length > 0)                 {                     return formats;                 }                 else                 {                     formats = new string[11];                      // Rfc3339DateTimePatterns                     formats[0] = 'yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffffK';                     formats[1] = 'yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'ffffffK';                     formats[2] = 'yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffK';                     formats[3] = 'yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'ffffK';                     formats[4] = 'yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffK';                     formats[5] = 'yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'ffK';                     formats[6] = 'yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fK';                     formats[7] = 'yyyy'-'MM'-'dd'T'HH':'mm':'ssK';                      // Fall back patterns                     formats[8] = 'yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffffK'; // RoundtripDateTimePattern                     formats[9] = DateTimeFormatInfo.InvariantInfo.UniversalSortableDateTimePattern;                     formats[10] = DateTimeFormatInfo.InvariantInfo.SortableDateTimePattern;                      return formats;                 }             }         }         #endregion          //============================================================         //  Public Methods         //============================================================         #region Parse(string s)         /// <summary>         /// Converts the specified string representation of a date and time to its <see cref='DateTime'/> equivalent.         /// </summary>         /// <param name='s'>A string containing a date and time to convert.</param>         /// <returns>A <see cref='DateTime'/> equivalent to the date and time contained in <paramref name='s'/>.</returns>         /// <remarks>         /// The string <paramref name='s'/> is parsed using formatting information in the <see cref='DateTimeFormatInfo.InvariantInfo'/> object.         /// </remarks>         /// <exception cref='ArgumentNullException'><paramref name='s'/> is a <b>null</b> reference (Nothing in Visual Basic).</exception>         /// <exception cref='FormatException'><paramref name='s'/> does not contain a valid RFC 3339 string representation of a date and time.</exception>         public static DateTime Parse(string s)         {             //------------------------------------------------------------             //  Validate parameter             //------------------------------------------------------------             if(s == null)             {                 throw new ArgumentNullException('s');             }              DateTime result;             if (Rfc3339DateTime.TryParse(s, out result))             {                 return result;             }             else             {                 throw new FormatException(String.Format(null, '{0} is not a valid RFC 3339 string representation of a date and time.', s));             }         }         #endregion          #region ToString(DateTime utcDateTime)         /// <summary>         /// Converts the value of the specified <see cref='DateTime'/> object to its equivalent string representation.         /// </summary>         /// <param name='utcDateTime'>The Coordinated Universal Time (UTC) <see cref='DateTime'/> to convert.</param>         /// <returns>A RFC 3339 string representation of the value of the <paramref name='utcDateTime'/>.</returns>         /// <remarks>         /// <para>         /// This method returns a string representation of the <paramref name='utcDateTime'/> that          /// is precise to the three most significant digits of the seconds fraction; that is, it represents          /// the milliseconds in a date and time value.         /// </para>         /// <para>         /// While it is possible to display higher precision fractions of a second component of a time value,          /// that value may not be meaningful. The precision of date and time values depends on the resolution          /// of the system clock. On Windows NT 3.5 and later, and Windows Vista operating systems, the clock's          /// resolution is approximately 10-15 milliseconds.         /// </para>         /// </remarks>         /// <exception cref='ArgumentException'>The specified <paramref name='utcDateTime'/> object does not represent a <see cref='DateTimeKind.Utc'>Coordinated Universal Time (UTC)</see> value.</exception>         public static string ToString(DateTime utcDateTime)         {             if (utcDateTime.Kind != DateTimeKind.Utc)             {                 throw new ArgumentException('utcDateTime');             }              return utcDateTime.ToString(Rfc3339DateTime.Rfc3339DateTimeFormat, DateTimeFormatInfo.InvariantInfo);         }         #endregion          #region TryParse(string s, out DateTime result)         /// <summary>         /// Converts the specified string representation of a date and time to its <see cref='DateTime'/> equivalent.         /// </summary>         /// <param name='s'>A string containing a date and time to convert.</param>         /// <param name='result'>         /// When this method returns, contains the <see cref='DateTime'/> value equivalent to the date and time          /// contained in <paramref name='s'/>, if the conversion succeeded,          /// or <see cref='DateTime.MinValue'>MinValue</see> if the conversion failed.          /// The conversion fails if the s parameter is a <b>null</b> reference (Nothing in Visual Basic),          /// or does not contain a valid string representation of a date and time.          /// This parameter is passed uninitialized.         /// </param>         /// <returns><b>true</b> if the <paramref name='s'/> parameter was converted successfully; otherwise, <b>false</b>.</returns>         /// <remarks>         /// The string <paramref name='s'/> is parsed using formatting information in the <see cref='DateTimeFormatInfo.InvariantInfo'/> object.         /// </remarks>         public static bool TryParse(string s, out DateTime result)         {             //------------------------------------------------------------             //  Attempt to convert string representation             //------------------------------------------------------------             bool wasConverted   = false;             result              = DateTime.MinValue;              if (!String.IsNullOrEmpty(s))             {                 DateTime parseResult;                 if (DateTime.TryParseExact(s, Rfc3339DateTime.Rfc3339DateTimePatterns, DateTimeFormatInfo.InvariantInfo, DateTimeStyles.AdjustToUniversal, out parseResult))                 {                     result          = DateTime.SpecifyKind(parseResult, DateTimeKind.Utc);                     wasConverted    = true;                 }             }              return wasConverted;         }         #endregion     } }