R.cond 无法读取未定义的属性 'length'

Question

  const getStats = response => R.reduce(
    R.cond([
      (accum, val) => isCompleted(val), someIrrelevantFn,
      (accum, val) => isOngoing(val), someOtherIrrelevantFn
    ]),
    { planned: R.path(['data', 'length'], response), ongoing: 0, completed: 0 },
    response.data
  )

当我调用 getStats(response) 时，其中 response.data 是一个数组（我已经验证了这一点），R.cond 抛出以下错误：

(node:40290) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'length' of undefined
    at /Users/ash/dev/project/node_modules/ramda/src/cond.js:42:20
    at _map (/Users/ash/dev/project/node_modules/ramda/src/internal/_map.js:6:19)
    at map (/Users/ash/dev/project/node_modules/ramda/src/map.js:64:14)
    at /Users/ash/dev/project/node_modules/ramda/src/internal/_dispatchable.js:41:15
    at f2 (/Users/ash/dev/project/node_modules/ramda/src/internal/_curry2.js:29:14)
    at Object.cond (/Users/ash/dev/project/node_modules/ramda/src/cond.js:41:30)
    at Object.f1 [as cond] (/Users/ash/dev/project/node_modules/ramda/src/internal/_curry1.js:18:17)
    at XWrap.console.log.R.reduce [as f] (/Users/ash/dev/project/functions/commands/statsinfo.js:37:25)
    at XWrap.@@transducer/step (/Users/ash/dev/project/node_modules/ramda/src/internal/_xwrap.js:12:17)
    at _arrayReduce (/Users/ash/dev/project/node_modules/ramda/src/internal/_reduce.js:11:34)
(node:40290) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)

这发生在任何谓词被调用之前，但无论如何 isComplete 和 isOngoing 看起来像这样：

  const isCompleted = R.compose(
    R.pathEq(['value', 'name'], 'Done'),
    R.find(R.pathEq(['customFields', 'field', 'name'], 'State')),
    R.prop('fields')
  )

  const isOngoing = R.complement(isCompleted)

我正在使用节点 10.16.0 如果有任何相关性，任何建议将不胜感激

Answer 1

你好像打错了cond。输入是一个数组数组，内部数组看起来像 [testFn, consequentFn].

我认为这会解决问题：

const getStats = response => R.reduce(
  R.cond([
    [(accum, val) => isCompleted(val), someIrrelevantFn],
//  ^                                                  ^
    [(accum, val) => isOngoing(val), someOtherIrrelevantFn]
//  ^                                                     ^
  ]),
  { planned: R.path(['data', 'length'], response), ongoing: 0, completed: 0 },
  response.data
)

R.cond 无法读取未定义的属性 'length'

R.cond Cannot read property 'length' of undefined

ramda.js

R.cond 无法读取未定义的 属性 'length'

R.cond Cannot read property 'length' of undefined

ramda.js

R.cond 无法读取未定义的属性 'length'