Class CronExpression

Namespace

Quartz

Assembly

Quartz.dll

Provides a parser and evaluator for unix-like cron expressions. Cron expressions provide the ability to specify complex time combinations such as "At 8:00am every Monday through Friday" or "At 1:30am every last Friday of the month".

[Serializable]
public sealed class CronExpression : ISerializable, IEquatable<CronExpression>, IParsable<CronExpression>

Inheritance

object

CronExpression

Implements

ISerializable

IEquatable<CronExpression>

IParsable<CronExpression>

Inherited Members

object.Equals(object, object)

object.GetType()

object.ReferenceEquals(object, object)

Remarks

Cron expressions are comprised of 6 required fields and one optional field separated by white space. The fields respectively are described as follows:

Field Name		Allowed Values		Allowed Special Characters
Seconds		0-59		, - /// /
Minutes		0-59		, - /// /
Hours		0-23		, - /// /
Day-of-month		1-31		, - /// ? / L W C
Month		1-12 or JAN-DEC		, - /// /
Day-of-Week		1-7 or SUN-SAT		, - /// ? / L #
Year (Optional)		empty, 1970-(the current year plus 100)		, - /// /

The '*' character is used to specify all values. For example, "*" in the minute field means "every minute".

The '?' character is allowed for the day-of-month and day-of-week fields. It is used to specify 'no specific value', and is a synonym for '*' there: both say that the field names no days, so the other field decides. When both day fields name days the expression fires on the union of the two, and when neither does it fires every day.

The '-' character is used to specify ranges. For example "10-12" in the hour field means "the hours 10, 11 and 12".

The ',' character is used to specify additional values. For example "MON,WED,FRI" in the day-of-week field means "the days Monday, Wednesday, and Friday".

The '/' character is used to specify increments. For example "0/15" in the seconds field means "the seconds 0, 15, 30, and 45". And "5/15" in the seconds field means "the seconds 5, 20, 35, and 50". Specifying '*' before the '/' is equivalent to specifying 0 is the value to start with. Essentially, for each field in the expression, there is a set of numbers that can be turned on or off. For seconds and minutes, the numbers range from 0 to 59. For hours 0 to 23, for days of the month 1 to 31, and for months 1 to 12. The "/" character simply helps you turn on every "nth" value in the given set. Thus, "7/6" in the month field only turns on month "7", it does NOT mean every 6th month, please note that subtlety.

The 'L' character is allowed for the day-of-month and day-of-week fields. This character is short-hand for "last", but it has different meaning in each of the two fields. For example, the value "L" in the day-of-month field means "the last day of the month" - day 31 for January, day 28 for February on non-leap years. If used in the day-of-week field by itself, it simply means "7" or "SAT". But if used in the day-of-week field after another value, it means "the last xxx day of the month" - for example "6L" means "the last friday of the month". You can also specify an offset from the last day of the month, such as "L-3" which would mean the third-to-last day of the calendar month. When using the 'L' option, it is important not to specify lists, or ranges of values, as you'll get confusing/unexpected results.

The 'W' character is allowed for the day-of-month field. This character is used to specify the weekday (Monday-Friday) nearest the given day. As an example, if you were to specify "15W" as the value for the day-of-month field, the meaning is: "the nearest weekday to the 15th of the month". So if the 15th is a Saturday, the trigger will fire on Friday the 14th. If the 15th is a Sunday, the trigger will fire on Monday the 16th. If the 15th is a Tuesday, then it will fire on Tuesday the 15th. However, if you specify "1W" as the value for day-of-month, and the 1st is a Saturday, the trigger will fire on Monday the 3rd, as it will not 'jump' over the boundary of a month's days. The 'W' character can only be specified when the day-of-month is a single day, not a range or list of days.

The 'L' and 'W' characters can also be combined for the day-of-month expression to yield 'LW', which translates to "last weekday of the month".

The '#' character is allowed for the day-of-week field. This character is used to specify "the nth" XXX day of the month. For example, the value of "6#3" in the day-of-week field means the third Friday of the month (day 6 = Friday and "#3" = the 3rd one in the month). Other examples: "2#1" = the first Monday of the month and "4#5" = the fifth Wednesday of the month. Note that if you specify "#5" and there is not 5 of the given day-of-week in the month, then no firing will occur that month. If the '#' character is used, there can only be one expression in the day-of-week field ("3#1,6#3" is not valid, since there are two expressions).

The legal characters and the names of months and days of the week are not case-sensitive.

NOTES:

• Support for specifying both a day-of-week and a day-of-month value is not complete (you'll need to use the '?' character in one of these fields).
• Overflowing ranges are supported - that is, having a larger number on the left-hand side than the right. You might do 22-2 to catch 10 o'clock at night until 2 o'clock in the morning, or you might have NOV-FEB. It is very important to note that overuse of overflowing ranges creates ranges that don't make sense and no effort has been made to determine which interpretation CronExpression chooses. An example would be "0 0 14-6 ? * FRI-MON".

Constructors

CronExpression(string)

Constructs a new CronExpressionString based on the specified parameter.

public CronExpression(string cronExpression)

Parameters

cronExpression string

String representation of the cron expression the new object should represent

Remarks

An @ macro - @yearly, @annually, @monthly, @weekly, @daily, @midnight or @hourly - is expanded here, which is what puts it behind every entry point that reads an expression string. The expansion is what CronExpressionString then holds, in the same way that it holds MON-FRI for a caller who wrote mon-fri.

Exceptions

ArgumentNullException

cronExpression is null.

FormatException

cronExpression is not a valid cron expression.

CronExpression(string, TimeZoneInfo?)

Constructs a new CronExpression resolved in the given time zone.

public CronExpression(string cronExpression, TimeZoneInfo? timeZone)

Parameters

cronExpression string

String representation of the cron expression the new object should represent

timeZone TimeZoneInfo

The time zone the expression's times are resolved in; null means the system's local time zone.

Properties

CronExpressionString

Gets the cron expression string.

public string CronExpressionString { get; }

Property Value

string

The cron expression string.

TimeZone

Gets the time zone the expression's times are resolved in. Defaults to the system's local time zone.

public TimeZoneInfo TimeZone { get; }

Property Value

TimeZoneInfo

Remarks

A CronExpression is immutable; use WithTimeZone(TimeZoneInfo?) to get a copy resolved in another time zone.

Methods

Equals(CronExpression?)

Determines whether the specified CronExpression is equal to the current CronExpression.

public bool Equals(CronExpression? other)

Parameters

other CronExpression

The CronExpression to compare with the current CronExpression.

Returns

bool

true if the specified CronExpression is equal to the current CronExpression; otherwise, false.

Equals(object?)

Determines whether the specified object is equal to the current object.

public override bool Equals(object? obj)

Parameters

obj object

The object to compare with the current object.

Returns

bool

true if the specified object is equal to the current object; otherwise, false.

GetHashCode()

Serves as a hash function for a particular type.

public override int GetHashCode()

Returns

int

A hash code for the current object.

GetNextInvalidTimeAfter(DateTimeOffset)

Returns the next date/time after the given date/time which does not satisfy the expression.

public DateTimeOffset? GetNextInvalidTimeAfter(DateTimeOffset date)

Parameters

date DateTimeOffset

the date/time at which to begin the search for the next invalid date/time

Returns

DateTimeOffset?

The first whole second at or after date that this expression does not fire at, or null when it fires at every second through to the give-up year.

Remarks

The expression fires on whole seconds, so the answer is the first whole second at or after date that it does not fire at. It is read off the expression's own field sets rather than walked to: the complement of a cron field is as enumerable as the field is, so a run of firing seconds is stepped over a minute, an hour, a day or a month at a time.

An expression can fire at every second there is — * * * * * ? is the plain one — and then there is no such time to return. That answers null rather than walking a century, one second at a time, to the year the scheduler gives up looking for a fire in.

GetNextValidTimeAfter(DateTimeOffset)

Returns the next date/time after the given date/time which satisfies the cron expression.

public DateTimeOffset? GetNextValidTimeAfter(DateTimeOffset date)

Parameters

date DateTimeOffset

the date/time at which to begin the search for the next valid date/time

Returns

DateTimeOffset?

the next valid date/time

GetObjectData(SerializationInfo, StreamingContext)

Writes this expression's fields into a serialization payload.

[SecurityCritical]
public void GetObjectData(SerializationInfo info, StreamingContext context)

Parameters

info SerializationInfo

The payload being written.

context StreamingContext

The serialization context.

GetPreviousValidTimeBefore(DateTimeOffset)

Returns the latest time before endTime that this expression fires at, the mirror of GetNextValidTimeAfter(DateTimeOffset).

public DateTimeOffset? GetPreviousValidTimeBefore(DateTimeOffset endTime)

Parameters

endTime DateTimeOffset

The instant to search back from; the result is strictly before it.

Returns

DateTimeOffset?

The preceding fire time, or null when the expression has none.

IsSatisfiedBy(DateTimeOffset)

Indicates whether the given date satisfies the cron expression.

public bool IsSatisfiedBy(DateTimeOffset dateUtc)

Parameters

dateUtc DateTimeOffset

The date to evaluate.

Returns

bool

a boolean indicating whether the given date satisfies the cron expression

Remarks

Note that milliseconds are ignored, so two Dates falling on different milliseconds of the same second will always have the same result here.

Parse(string)

Parses a cron expression string into a CronExpression.

public static CronExpression Parse(string cronExpression)

Parameters

cronExpression string

String representation of the cron expression.

Returns

CronExpression

The parsed expression.

Exceptions

ArgumentNullException

cronExpression is null.

FormatException

cronExpression is not a valid cron expression.

Parse(string, CronFormat)

Parses a cron expression string written in the given format into a CronExpression.

public static CronExpression Parse(string cronExpression, CronFormat format)

Parameters

cronExpression string

String representation of the cron expression.

format CronFormat

The dialect cronExpression is written in.

Returns

CronExpression

The parsed expression.

Remarks

Unix reads the five-field crontab form, whose day-of-week is numbered 0-7 with both 0 and 7 meaning Sunday. The result is an ordinary CronExpression holding the canonical Quartz spelling of the same schedule, so "30 4 * * 1" becomes "0 30 4 ? * MON" and that is what CronExpressionString, the dashboard and the database show. The format is not recorded anywhere and the original text is not recoverable.

A time zone composes: CronExpression.Parse(s, CronFormat.Unix).WithTimeZone(tz).

Exceptions

ArgumentNullException

cronExpression is null.

ArgumentOutOfRangeException

format is not a cron format.

FormatException

cronExpression is not a valid cron expression in format.

ParseWithHash(string, CronFormat, int)

Parses a cron expression string written in the given format, whose H (hash) tokens are resolved against the given integer seed.

public static CronExpression ParseWithHash(string cronExpression, CronFormat format, int hashSeed)

Parameters

cronExpression string

Cron expression that may contain H tokens.

format CronFormat

The dialect cronExpression is written in.

hashSeed int

An integer seed the hash values are derived from.

Returns

CronExpression

The parsed expression, with every H token resolved to a value.

Remarks

The expression is read as the Quartz expression that says the same thing before its H tokens are resolved, so a token is hashed over the range the field has in Quartz — an H in a five-field day-of-week is spread over 1-7, not 0-7. What comes back is an ordinary CronExpression in the canonical Quartz spelling, as Parse(string, CronFormat) describes.

Exceptions

ArgumentNullException

cronExpression is null.

FormatException

cronExpression is not a valid cron expression in format.

See Also

ParseWithHash(string, int)

ParseWithHash(string, CronFormat, string)

Parses a cron expression string written in the given format, whose H (hash) tokens are resolved against the given hash key.

public static CronExpression ParseWithHash(string cronExpression, CronFormat format, string hashKey)

Parameters

cronExpression string

Cron expression that may contain H tokens.

format CronFormat

The dialect cronExpression is written in.

hashKey string

A stable string key the hash values are derived from (e.g. the trigger name).

Returns

CronExpression

The parsed expression, with every H token resolved to a value.

Remarks

The expression is read as the Quartz expression that says the same thing before its H tokens are resolved, so a token is hashed over the range the field has in Quartz — an H in a five-field day-of-week is spread over 1-7, not 0-7. What comes back is an ordinary CronExpression in the canonical Quartz spelling, as Parse(string, CronFormat) describes.

Exceptions

ArgumentNullException

cronExpression or hashKey is null.

FormatException

cronExpression is not a valid cron expression in format.

See Also

ParseWithHash(string, string)

ParseWithHash(string, int)

Parses a cron expression string whose H (hash) tokens are resolved against the given integer seed.

public static CronExpression ParseWithHash(string cronExpression, int hashSeed)

Parameters

cronExpression string

Cron expression that may contain H tokens.

hashSeed int

An integer seed the hash values are derived from.

Returns

CronExpression

The parsed expression, with every H token resolved to a value.

Exceptions

ArgumentNullException

cronExpression is null.

FormatException

cronExpression is not a valid cron expression.

See Also

ResolveHash(string, int)

ParseWithHash(string, string)

Parses a cron expression string whose H (hash) tokens are resolved against the given hash key. The key is typically the trigger or job name, so that every trigger written with the same expression lands on a different minute instead of all firing at once.

public static CronExpression ParseWithHash(string cronExpression, string hashKey)

Parameters

cronExpression string

Cron expression that may contain H tokens.

hashKey string

A stable string key the hash values are derived from (e.g. the trigger name).

Returns

CronExpression

The parsed expression, with every H token resolved to a value.

Exceptions

ArgumentNullException

cronExpression or hashKey is null.

FormatException

cronExpression is not a valid cron expression.

See Also

ResolveHash(string, string)

ResolveHash(string, int)

Resolves H (hash) tokens in a cron expression to deterministic numeric values based on the given integer seed.

public static string ResolveHash(string cronExpression, int hashSeed)

Parameters

cronExpression string

Cron expression that may contain H tokens

hashSeed int

An integer seed used to derive hash values

Returns

string

A standard cron expression string with all H tokens resolved to numeric values

Remarks

A leading @ macro is expanded first, as the constructor expands it, so a macro means the same schedule here as everywhere else.

ResolveHash(string, string)

Resolves H (hash) tokens in a cron expression to deterministic numeric values based on the given hash key. The resulting expression is a standard cron expression with no H tokens.

public static string ResolveHash(string cronExpression, string hashKey)

Parameters

cronExpression string

Cron expression that may contain H tokens

hashKey string

A stable string key used to derive hash values (e.g., trigger name)

Returns

string

A standard cron expression string with all H tokens resolved to numeric values

Remarks

The H symbol can be thought of as a deterministic value over a range, derived from a hash of the key. It produces stable scheduling that spreads load across time.

Supported H token forms:

• H — hash value within the full range of the field
• H(min-max) — hash value within the specified range
• H/step — hash-derived offset, then every step
• H(min-max)/step — hash-derived offset in range, then every step

A leading @ macro is expanded first, as the constructor expands it, so a macro means the same schedule here as everywhere else. A macro names a whole schedule and so carries no H token; it simply passes through with nothing to resolve.

ToString()

Returns the string representation of the CronExpression

public override string ToString()

Returns

string

The string representation of the CronExpression

TryParse(string?, out CronExpression?)

Attempts to parse a cron expression string into a CronExpression.

public static bool TryParse(string? cronExpression, out CronExpression? result)

Parameters

cronExpression string

String representation of the cron expression; may be null.

result CronExpression

The parsed expression, or null when parsing failed.

Returns

bool

true when cronExpression is a valid cron expression.

TryParse(string?, CronFormat, out CronExpression?)

Attempts to parse a cron expression string written in the given format into a CronExpression.

public static bool TryParse(string? cronExpression, CronFormat format, out CronExpression? result)

Parameters

cronExpression string

String representation of the cron expression; may be null.

format CronFormat

The dialect cronExpression is written in.

result CronExpression

The parsed expression, or null when parsing failed.

Returns

bool

true when cronExpression is a valid cron expression in format. An undefined format answers false as well: a Try that throws is a Try its caller has to wrap, which is the thing it exists to save them.

See Also

Parse(string, CronFormat)

TryParseWithHash(string?, CronFormat, string, out CronExpression?)

Attempts to parse a cron expression string written in the given format, whose H (hash) tokens are resolved against the given hash key.

public static bool TryParseWithHash(string? cronExpression, CronFormat format, string hashKey, out CronExpression? result)

Parameters

cronExpression string

Cron expression that may contain H tokens; may be null.

format CronFormat

The dialect cronExpression is written in.

hashKey string

A stable string key the hash values are derived from (e.g. the trigger name).

result CronExpression

The parsed expression, or null when parsing failed.

Returns

bool

true when cronExpression is a valid cron expression in format under hashKey.

Remarks

The expression is read as the Quartz expression that says the same thing before its H tokens are resolved, so a token is hashed over the range the field has in Quartz — an H in a five-field day-of-week is spread over 1-7, not 0-7. What comes back is an ordinary CronExpression in the canonical Quartz spelling, as Parse(string, CronFormat) describes.

Exceptions

ArgumentNullException

hashKey is null.

See Also

TryParseWithHash(string?, string, out CronExpression?)

TryParseWithHash(string?, string, out CronExpression?)

Attempts to parse a cron expression string whose H (hash) tokens are resolved against the given hash key.

public static bool TryParseWithHash(string? cronExpression, string hashKey, out CronExpression? result)

Parameters

cronExpression string

Cron expression that may contain H tokens; may be null.

hashKey string

A stable string key the hash values are derived from (e.g. the trigger name).

result CronExpression

The parsed expression, or null when parsing failed.

Returns

bool

true when cronExpression is a valid cron expression under hashKey.

Remarks

An H token can be malformed in its own right — H(0-60) names a minute that does not exist — so the resolution is inside the attempt rather than ahead of it.

Exceptions

ArgumentNullException

hashKey is null.

WithTimeZone(TimeZoneInfo?)

Returns a copy of this expression resolved in the given time zone.

public CronExpression WithTimeZone(TimeZoneInfo? timeZone)

Parameters

timeZone TimeZoneInfo

The time zone the copy's times are resolved in; null means the system's local time zone.

Returns

CronExpression

A new CronExpression with the same expression string, or this instance when the time zone would not change.