Question

我想创建一个类似的功能，以这种方式使用：

const objectCreator = createObject({
  foo: functionFoo,
  bar: functionBar
})

objectCreator(42) // => { foo: functionFoo(42), bar: functionBar(42) }

因此，想法是从应用于值的一组函数中创建一个对象。例如，用例是从一个唯一的对象中提取不同的数据，然后将此函数放入管道中。

我可以手动创建这样的功能，但是在Ramda（或类似产品）中是否已经不存在此功能？我不知道怎么命名。

Answer 1

Map可以满足您的大部分需求，但前提是您要用代码包围起来以提供正确的值。例如：

--create some sample data that you gave

declare @inventory table (  PartNumber int, 
                            Quantity int, 
                            NewCount int, 
                            diff int)

insert into @inventory
values
(2871451,1,0,1),
(4932615,6,1,5)

declare @PARTSREMAININGFIFO table ( id int, 
                                    PartNumber int, 
                                    PartDescription varchar(64), 
                                    Quantity int, 
                                    TotalPrice decimal (8,6), 
                                    brand varchar(64), 
                                    Location varchar(16), 
                                    Account varchar(64))

insert into @PARTSREMAININGFIFO
values

(9183,2871451,'AFM DEVICE GASKET',1,19.815225,'CUMMINS','A1','6015-Z'),
(9183,2871451,'AFM DEVICE GASKET',1,19.815225,'CUMMINS','A2','6015-Z'), --notice the extra (2nd) row here for part 2871451
(9183,2871451,'AFM DEVICE GASKET',1,19.815225,'CUMMINS','A3','6015-Z'), --notice the extra (3nd) row here for part 2871451

(3264,4932615,'GASKET',1,2.907144,'CUMMINS','A1','6015-Z'),
(9780,4932615,'GASKET',1,5.053475,'CUMMINS','A1','6015-Z'),
(9781,4932615,'GASKET',1,5.053475,'CUMMINS','A1','6015-Z'),
(9782,4932615,'GASKET',1,5.053475,'CUMMINS','A1','6015-Z'),
(9783,4932615,'GASKET',1,5.053475,'CUMMINS','A1','6015-Z'),
(9783,4932615,'GASKET',1,5.053475,'CUMMINS','A6','6015-Z')  --notice the 6th (extra) row here for part 4932615


--staging table for your results

declare @tempResults table (        id int, 
                                    PartNumber int, 
                                    PartDescription varchar(64), 
                                    Quantity int, 
                                    TotalPrice decimal (8,6), 
                                    brand varchar(64), 
                                    Location varchar(16), 
                                    Account varchar(64))



declare cur cursor local fast_forward for 
select distinct 
    PartNumber,
    diff 
from (select 
            PartNumber, 
            Quantity, 
            NewCount, 
            diff
        from @inventory
        where NewCount <> Quantity) x

declare @partNumber int
declare @diff int

open cur

fetch next from cur into @partNumber, @diff 

while @@FETCH_STATUS = 0
begin
    insert into @tempResults
    select top (@diff) 
        id, 
        PartNumber, 
        PartDescription, 
        Quantity, 
        TotalPrice,
        Brand, 
        Location, 
        Account
    from @PARTSREMAININGFIFO
    where PartNumber = @partNumber
    order by Quantity   --note you need to specify WHAT you want to order by 

    fetch next from cur into @partNumber, @diff 
end


select * 
from @tempResults
order by PartNumber

close cur
deallocate cur

或者如果您希望将其咖喱处理（因此您可以同时或分别传入规范和值）：

const createObject = specification => value => R.map(f => f(value), specification);

const objectCreator = createObject({
  foo: val => val * 2,
  bar: val => val + 1,
});

let result = objectCreator(42); // { foo: 84, bar: 43 }

编辑：

如果输入的顺序颠倒了（即先输入值，后指定），则会更简单：

const createObject = R.curry((specification, value) => R.map(f => f(value), specification))

let result = createObject({
  foo: val => val * 2,
  bar: val => val + 1,
}, 42); // { foo: 84, bar: 43 }

Answer 2

applySpec这样做：

const functionFoo = x => 'Foo: ' + x;
const functionBar = x => 'Bar: ' + x;

const objectCreator = applySpec({
  foo: functionFoo,
  bar: functionBar
});

objectCreator(42); // {"bar": "Bar: 42", "foo": "Foo: 42"}

用Ramda创建对象

2 个答案: