Split mapper

[lowkeypriority]

Description

I've been added split mapper and unit test for it.
Also added a description in README, but I don't know how to write an axample :\

Closes #24

"Roadmap"

• splitMapper
  • Add file
  • Reexport in mappers/index.ts
  • Add unit test
  • Add section in README

[Siemienik]

@lowkeypriority it's nice to see your PR 😸
I have two suggestions for you:

1. could I ask you to do one issue in one PR? the fewer scope is much easier to review and maintain :) Additionally, it may be much quicker merge into master
2. for the split mapper, may I recommend to create a factory? Something like that:

const factory = (options) => {
  const splitMapper = (value) => value.split(options.separator);

  splitMapper.separator = (separator) => factory({...options, separator});

  return splitMapper;
}

export const splitMapper = factory({separator: ','}); // create default split mapper

usage:

importer.GetAllItems({
  workshet:'Authors',
  type: ' list',
  columns:[
     {key:"fullname", index:1},
     {key: "books", index:2, mapper:splitMapper}, // map from `"book1,book2"` to `["book1","book2"]`
     {key: "adwards", index:3, mapper:splitMapper.separator(' && ')}, // map from `"2020 Adward && 2019 Adward"` to `["2020 Adward","2019 Adward"]`
  ]
});

[Siemienik]

ups.. It wasn't expected to close it... It was done automatically after #20 become merged

[lowkeypriority]

@Siemienik thanks for review. I'll try to rewrite mappers to factory

Also I'll rename issue – one issue - one PR is food practice :)

[lowkeypriority]

@Siemienik Hello again.
I tried to implement the factory pattern but without success:

1. I've created abstract class for mappers:

export abstract class Mapper {
  private options: object

  constructor(options: object) {
    this.options = options
  }

  abstract valueOf(value: string): string | string[]
}

2. Made SplitMapper class extended from Mapper:

import { Mapper } from "./mapperFactory"

export class SplitMapper extends Mapper {
  constructor(options: object) {
    super({...options, separator: ','})
  }

  valueOf(value: string) {
    value.split(this.options.separator)
  }

  separator(separator: string) {
    this.options.separator = separator
  }
}

But this solution is not good at all - it contains TypeGuard bugs and, in my opinion, lacks a good abstraction.

Can you help with this? Any advice?

[Siemienik]

@lowkeypriority code what I write works:

there is only lack of types.

As a mappers is used as lambda function matches to: (value: string) => any it isn't required to introduce classes and abstracts.

[Siemienik]

Can you help with this? Any advice?

1. If I were doing this issue, probably I would like to create type ValueMapper<TResult> in src/config/ValueMapper.ts and use it in:

* https://github.com/Siemienik/xlsx-import/blob/master/src/config/IFieldConfig.ts#L5
* https://github.com/Siemienik/xlsx-import/blob/master/src/config/IColumnConfig.ts#L4
**EDIT: resolved in: #29 **

2. Then create additional type: (above mapper implementation in same file like splitMapper)

  type SplitMapper = 
     ValueMapper<Array<string>>  // fulfil mapper behaviour 
     & {separator: (separator:string) => SplitMapper};` // adding api for customisations

[Siemienik]

@lowkeypriority I've just updated the master branch. I added there the simplest example for a mapper (which essentially does nothing):

https://github.com/Siemienik/xlsx-import/blob/9a92510226a4c81d4d7030bc6632e9da8480e2d1/src/mappers/stringMapper.ts#L1-L3

and test for it:

https://github.com/Siemienik/xlsx-import/blob/9a92510226a4c81d4d7030bc6632e9da8480e2d1/tests/unit/mappers/stringMapper.test.ts#L1-L31

I suppose it will be handful for you 😸

[Siemienik]

@lowkeypriority how do you up to? Is any way how can I help you?

[Siemienik]

suddenly I have to close this PR because lack of activity here, please open new one if needed