如何更新 JSON 数组中的属性 - Ramdajs

Question

输入：

[{
    message: 'A1 Message, B1 Message, C1 Message'
}, {
    message: 'A1 Message, B1 Message'
}];

Output：

[{
    message: 'C1 Message'
}, {
    message: null
}];

识别特定消息“C1”（子字符串）并更新字符串或在对象数组中设置为 null

尝试了以下：

var input = [{
    id: 1,
    message: 'A1 Message, B1 Message, C1 Message'
}, {
    id: 2,
    message: 'A1 Message, B1 Message'
}];

var updateMessage = (obj) => {
    var C1Message = R.pipe(
        R.prop('message'),
        R.splitAt(obj.message.indexOf('C1')),
        R.last
    )(obj);
    return R.assoc('message', C1Message, obj);
}

var updateArray = R.map(R.when(R.pipe(R.prop('message'), R.includes('C1')), updateMessage));
var output = updateArray(input);
console.log(output);

如何使用ifElse将第二条object消息设置为null？

Answer 1

你可以进化数组中的每个 object。 对于每条message ，请尝试匹配您需要的消息格式。 如果未找到匹配项（空数组），则返回null 。 如果找到匹配项， R.match的结果中取出第一个元素：

 const { map, evolve, pipe, match, ifElse, isEmpty, always, head } = R const fn = map(evolve({ message: pipe( match(/C1[^,]+/), // match C1 message ifElse(isEmpty, always(null), // if empty assign null head // if not take the 1st element ) ) })) const data = [{ message: 'A1 Message, B1 Message, C1 Message' }, { message: 'A1 Message, B1 Message' }]; const result = fn(data) console.log(result)

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动态使用 - 将 RegExp 作为参数传递：

 const { map, evolve, pipe, match, ifElse, isEmpty, always, join } = R const fn = regexp => map(evolve({ message: pipe( match(regexp), // match a RegExp ifElse(isEmpty, always(null), // if empty assign null join(', ') // if not convert to a string ) ) })) const data = [{ message: 'A1 Message, B1 Message, C1 Message 1, C1 Message 2' }, { message: 'A1 Message, B1 Message' }]; const result = fn(/C1[^,]+/g)(data) console.log(result)

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