在 esper 语句中使用自定义类型属性的 Cumulocity

Question

我很难使用自定义类型的属性来编写上下文等语句。例如，这是有效的：

create context TripContext
  context PartionBySource
    partition by source from EventCreated,

  context ContextBorders
    initiated by EventCreated(
      type="c8y_SwitchPowerReport") as startEvent

    terminated by EventCreated(
      type="c8y_SwitchPowerReport") as endEvent;

但这还不够，我需要检查我的一些自定义属性以更好地定义上下文。我希望能够做这样的事情：

create context TripContext
  context PartionBySource
    partition by
      source,
      getString(????, "customProp1"),
      getNumber(????, "customProp2"),
      ...
    from EventCreated,

  context ContextBorders
    initiated by EventCreated(
      type="c8y_SwitchPowerReport",
      getString(startEvent, "c8y_SwitchPower.newStatus") = "ON") as startEvent

    terminated by EventCreated(
      type="c8y_SwitchPowerReport",
      getString(endEvent, "c8y_SwitchPower.newStatus") = "OFF") as endEvent;

我不知道用什么代替 ????参考事件。它对 "native" 属性（如源、时间、类型等）是透明的。但是一旦有自定义属性，我就不知道如何访问它了。

至于 initiated/terminated 语法，有些东西真的很奇怪我不明白，但也许它更像是一个 Esper 而不是 Cumulocity 问题。这是有效的：

terminated by EventCreated(
  type="c8y_SwitchPowerReport",
  getString(endEvent, "c8y_SwitchPower.newStatus") = "OFF") as endEvent

但这不是：

initiated by EventCreated(
  type="c8y_SwitchPowerReport",
  getString(startEvent, "c8y_SwitchPower.newStatus") = "ON") as startEvent

我收到一条错误消息：

Failed to validate single-row function parameter expression 'startEvent': Property named 'startEvent' is not valid in any stream

如有任何见解，我们将不胜感激。

Answer 1

我也找不到像您尝试的那样快速获取它的方法运行。但我会推荐以下方法。如果您无论如何都与自定义片段有很大关系，那么通过提取此值的附加流运行事件是有意义的：

create schema MyCustomEvent(
  event Event,
  myCustomString String,
  myCustomNumber BigDecimal
);

insert into MyCustomEvent
select
  e.event as Event,
  getString(e, "myCustomString") as myCustomString,
  getNumber(e, "myCustomNumber") as myCustomNumber
from EventCreated e
where getString(e, "myCustomString") is not null
and getNumber(e, "myCustomNumber") is not null;

现在您可以轻松地在 MyCustomEvent 而不是 EventCreated 上创建上下文。

在 esper 语句中使用自定义类型属性的 Cumulocity

Cumulocity using custom type properties in esper statements

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