iCalendar“字段”列表（用于基于 iCalendar 标准的数据库模式）

Question

我的应用程序必须处理日历信息（包括单次出现、重复等）。为了轻松与其他应用程序交互，我认为直接基于 iCalendar 格式（字段、关系、约束）创建我的数据库模式是一个好主意，这样我就可以通过 ORM 获得 iCalendar 兼容的对象，我可以在何时轻松公开需要。

我知道 RFC 是可用的，但它有点复杂，因为其中包含我目前不使用的所有附加信息。

有人能指出一个更简单的来源来创建基于 iCal 标准的数据库架构（即字段/字段名称的列表及其与 iCal 条目的关系）吗？

谢谢！

Answer 1

我已经这样做了（仅适用于 VEvents，不支持 TODO 项目或期刊全文或类似的东西）。我的实现看起来像这样（在删除不特定于问题的列之后）：

-- One table for each event.  An event may have multiple rRules.
Create Table [vEvent]
    (vEventID Integer Identity(1, 1) Not Null
     Constraint [vEvent.pk]
     Primary Key
     Clustered
    ,title nVarChar(200) Not Null);

-- One table for rRules.
-- My application does NOT support the "bySetPos" rule, so that is not included.
Create Table [rRule]
    (rRuleID Integer Identity(1, 1) Not Null
     Constraint [rRule.pk]
     Primary Key
     Clustered
    ,vEventID Integer Not Null
     Constraint [fk.vEvent.rRules]
     Foreign Key
     References [vEvent] (vEventID)
     On Update Cascade
     On Delete Cascade
    ,[class]            varChar(  12) Not Null Default('public')
    ,[created]         DateTime       Not Null Default(getUTCDate())
    ,[description]     nVarChar(max)      Null
    ,[dtStart]         DateTime       Not Null
    ,[dtEnd]           DateTime           Null
    ,[duration]         varChar(  20)     Null
    ,[geoLat]          Float              Null
    ,[geoLng]          Float              Null
    ,[lastModified]    DateTime       Not Null Default(getUTCDate())
    ,[location]        nVarChar(max)      Null
    ,[organizerCN]     nVarChar(  50)     Null
    ,[organizerMailTo] nVarChar( 100)     Null
    ,[seq]             Integer        Not Null Default(0)
    ,[status]           varChar(   9) Not Null Default('confirmed')
    ,[summary]         nVarChar(  75)     Null
    ,[transparent]     Bit            Not Null Default(0)
    ,[freq]             varChar(   8) Not Null Default('daily')
    ,[until]           DateTime           Null
    ,[count]           Integer            Null
    ,[interval]        Integer        Not Null Default(1)
    ,[bySecond]         varChar( 170)     Null
    ,[byMinute]         varChar( 170)     Null
    ,[byHour]           varChar(  61)     Null
    ,[byDay]            varChar(  35)     Null
    ,[byMonthDay]       varChar( 200)     Null
    ,[byYearDay]        varChar(3078)     Null
    ,[byWeekNo]         varChar( 353)     Null
    ,[byMonth]          varChar(  29)     Null
    ,[wkSt]             Char   (   2)     Null Default('mo'));

-- Class must be one of "Confidential", "Private", or "Public"
Alter Table [rRule]
Add Constraint [rRule.ck.Class]
Check ([class] In ('confidential', 'private', 'public'));

-- Start date must come before End date
Alter Table [rRule]
Add Constraint [rRule.ck.dtStart]
Check ([dtEnd] Is Null Or [dtStart] <= [dtEnd]);

-- dtEnd and duration may not both be present
Alter Table [rRule]
Add Constraint [rRule.ck.duration]
Check (Not ([dtEnd] Is Not Null And [duration] Is Not Null));

-- Check valid values for [freq]. Note that 'single' is NOT in the RFC;
-- it is an optimization for my particular iCalendar calculation engine.
-- I use it as a clue that this pattern has only a single date (dtStart),
-- and there is no need to perform extra calculations on it.
Alter Table [rRule]
Add Constraint [rRule.ck.freq]
Check ([freq] In
    ('yearly'
    ,'monthly'
    ,'weekly'
    ,'daily'
    ,'hourly'
    ,'minutely'
    ,'secondly'
    ,'single')); -- Single is NOT part of the spec!

-- If there is a latitude, there must be a longitude, and vice versa.
Alter Table [rRule]
Add Constraint [rRule.ck.geo]
Check (([geoLat] Is Null And [geoLng] Is Null)
       Or ([geoLat] Is Not Null And [geoLng] Is Not Null));

-- Interval must be positive.
Alter Table [rRule]
Add Constraint [rRule.ck.interval]
Check ([interval] > 0);

-- Status has a set of defined values.
Alter Table [rRule]
Add Constraint [rRule.ck.status]
Check ([status] In ('cancelled', 'confirmed', 'tentative'));

-- Until and Count may not coexist in the same rule.
Alter Table [rRule]
Add Constraint [rRule.ck.until and count]
Check (Not ([until] Is Not Null And [count] Is Not Null));


-- One table for exceptions to rRules.  In my application, this covers both
-- exDate and rDate.  I do NOT support extended rule logic here;  The RFC says
-- you should support the same sort of date calculations here as are supported
-- in rRules: exceptions can recur, etc.  I don't do that; mine is simply a
-- set of dates that are either "exceptions" (dates which don't appear, even
-- if the rule otherwise says they should) or "extras" (dates which do appear,
-- even if the rule otherwise wouldn't include them).  This has proved
-- sufficient for my application, and something that can be exported into a
-- valid iCalendar file--even if I can't import an iCalendar file that makes
-- use of recurring rules for exceptions to recurring rules.
Create Table [exDate]
    (exDateID Integer Identity(1, 1) Not Null
     Constraint [exDate.pk]
     Primary Key
     Clustered
    ,rRuleID Integer Not Null
     Constraint [fk.rRule.exDates]
     Foreign Key
     References [rRule] (rRuleID)
     On Update Cascade
     On Delete Cascade
    ,[date] DateTime Not Null
    ,[type] varChar(6) Not Null);  -- Type = "exDate" or "rDate" for me; YMMV.

为此，我有几个 SQL Server 2005+ CLR 函数可用于计算各种事件的日期。我发现以下表格非常有用：

Select * From dbo.getDatesByVEventID(@id, @startDate, @endDate)
Select * From dbo.getEventsByDateRange(@startDate, @endDate, @maxCount)

上面的实现非常有趣！

Answer 2

是的，有点。 Sunbird（开源 mozilla 日历）基于 sqlite，我刚刚下载并解压缩了他们的源代码。它里面有 .sql 文件。

ftp://ftp.mozilla.org/pub/mozilla.org/calendar/sunbird/releases/0.9/source/

mozilla\calendar\providers\storage\schema-7.sql -- 这是 sunbird 用来制作有效 iCal 文件的架构，所以它不会太糟糕。

Answer 3

非常感谢 Chris Nielsen 提供的上述出色解决方案。但是，我遇到了一些问题，所以我对其进行了修改。请注意，上面的解决方案是在 python sqlalchemy 中。我很快就会转换它。

我对 Chris 的解决方案的主要困难（而且它们可能并不适用于所有人）是

1. 我不需要他的解决方案中的许多列。我只需要可以帮助我处理事件和重复的列。这是 iCalendar 规范的错，而不是 Chris 的错。我下面的解决方案仅根据日历限制和顺序限制考虑重复规则。

2. 某些列——最重要的是 dtStart 和 dtEnd——属于 VEVENT，而不是 RRULE，但 Chris 将它们放在 RRULE 中。这让我很困惑。 事件：https://www.rfc-editor.org/rfc/rfc5545#section-3.6.1 规则：https://www.rfc-editor.org/rfc/rfc5545#section-3.3.10

3. 我还需要弄清楚如何包含可能具有多种模式的时间表。例如，一个事件可能会在每周周五的下午 6 点至晚上 9 点发生，但也可能会在五一节的全天发生。这需要 dtStart 和 dtEnd 的灵活性。为此，我创建了一个包含表“SCHEDULE”，它与 EVENTS 保持多对多关系，而 EVENTS 与 RRULES 具有包含关系。

以下是我在 sqlalchemy 中的解决方案。我会尽快将其转换为 SQL。

from app import db
from sqlalchemy import CheckConstraint
from sqlalchemy.ext.associationproxy import association_proxy


class Schedule(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    subtypes_relation = db.relationship('Event', secondary=schedule_event_association,
                                        backref=db.backref('Schedule', lazy='dynamic'))

schedule_event_association = db.Table(
    'schedule_event_association',
    db.Column('schedule_id', db.Integer, db.ForeignKey('schedule.id')),
    db.Column('event_id', db.Integer, db.ForeignKey('event.id')))

class Event(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    dt_start = db.Column(db.DateTime)  # start time
    dt_end = db.Column(db.DateTime) # end time
    tz_id = db.Column(db.String) # Time Zone

    recurrence_rule = db.Column('RecurrenceRule_id',  db.Integer, db.ForeignKey('RecurrenceRule.id'))

# Start date must come before End date
    CheckConstraint('dtEnd is NULL OR dtStart <= dtEnd', name='Valid: Time Period')

class RecurrenceRule(db.Model):
    id = db.Column(db.Integer, primary_key=True)

    # Frequency Type
    freq = db.Column(db.String(8), nullable=False, default='weekly') # type of recurrence

    # Calendar-Based Rules
    byDay = db.Column(db.String(35))   # List of Day of the Week
                                        # "mo,tu,we" for weekly
                                        # "+2MO, -1MO" = second monday, last monday for yearly or monthly
    byMonthDay = db.Column(db.String(200)) # List of Day of the Month
                                            # +1,-1"
                                            # Only for Monthly or Yearly
    byYearDay = db.Column(db.String(3078)) # List Day of the Year
                                            #"+1, -1"
                                            # Only for yearly
                                            # Take care with leap years
    byWeekNo = db.Column(db.String(353)) # Which week of Mon`enter code here`th
                                            # "+5, -3" for fifth and third-to-last
                                            # Only for yearly
    byMonth = db.Column(db.String(29))   # Month of year.

    # Sequence-Based Rules
    until = db.Column(db.DateTime)   # last day of occurence
    count = db.Column(db.Integer)    # number of occurences
    interval = db.Column(db.Integer, nullable=False, default=1) # interval between recurrences
    bysetpos = db.Column(db.String()) # Specifies specific instances of recurrence


# Valid Values
    CheckConstraint(freq in ('yearly', 'monthly', 'weekly', 'daily', 'single'),
                    name='Valid: Frequency Value')
    CheckConstraint(interval > 0, name='Valid: Positive Interval')
    CheckConstraint(byDay is not None and freq in ('daily', 'yearly', 'monthly'))
    CheckConstraint(byWeekNo is not None and freq in ('yearly', 'monthly'))
    CheckConstraint(byYearDay is not None and freq == 'yearly')

# Until and Count may not coexist in the same rule.
    CheckConstraint(not (until is not None and count is not None),
                    name='Valid: Not Both Until and Count')

Answer 4

• 你可以试试这个苹果 icalendar 的文档。您可以将字段直接复制到数据库表中。 http://developer.apple.com/library/mac/#DOCUMENTATION/AppleApplications/Reference/SyncServicesSchemaRef/Articles/Calendars.html

• 如果您使用 java，ical4j 提供模式和接口之间的粘合剂。如果你不使用java，源码中的算法生成出现次数和结构会为实现提供很好的帮助。

Answer 5

iCal 是一个 Apple 应用程序，它遵循目前称为 Icalendar（以前的 Vcalendar 的继承者）的标准。我认为 wikipedia entry 包含您所需的所有信息，并且格式简单易懂，但是，如果需要，请随时寻求更多指导！！！