使用lodash合并数组

Question

I have this set of an array of objects:

 let x = [{ CategoryName: 'abc', Items: ['3A'] }, { CategoryName: 'xyz', Items: ['5Z'] }, { CategoryName: 'abc', Items: ['6B'] }, { CategoryName: 'abc', Items: ['9C'] }, { CategoryName: 'xyz', Items: ['1X'] } ]; 

what I want is:

[
    {CategoryName:'abc',Items['3A','6B','9C']},
    {CategoryName:'xyz',Items['1X','5Z']}
]

How I can I achieve this using lodash ?

Answer 1

You can group it by CategoryName and flatMap that result by Items . That's it!

_(x).groupBy('CategoryName').map((v, k)=> ({CategoryName: k, Items: _.flatMap(v, 'Items')})).value()

Working demo:

 let x = [{"CategoryName":"abc","Items":["3A"]},{"CategoryName":"xyz","Items":["5Z"]},{"CategoryName":"abc","Items":["6B"]},{"CategoryName":"abc","Items":["9C"]},{"CategoryName":"xyz","Items":["1X"]}], res; res = _(x).groupBy('CategoryName').map((v, k)=> ({CategoryName: k, Items: _.flatMap(v, 'Items')})).value(); console.log(res); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script> 

Answer 2

With lodash you could do this also with _.groupBy and mergeWith :

 let data = [{ CategoryName: 'abc', Items: ['3A'] }, { CategoryName: 'xyz', Items: ['5Z'] }, { CategoryName: 'abc', Items: ['6B'] }, { CategoryName: 'abc', Items: ['9C'] }, { CategoryName: 'xyz', Items: ['1X'] } ]; const result = _.map(_.groupBy(data, 'CategoryName'), x => _.mergeWith(...x, (o,s) => _.isArray(s) ? o.concat(s) : o)) console.log(result) 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.min.js"></script> 

Or with _.transform :

 let data = [{ CategoryName: 'abc', Items: ['3A'] }, { CategoryName: 'xyz', Items: ['5Z'] }, { CategoryName: 'abc', Items: ['6B'] }, { CategoryName: 'abc', Items: ['9C'] }, { CategoryName: 'xyz', Items: ['1X'] } ]; const result = _.transform(data, (r, {CategoryName, Items}) => { r[CategoryName] = r[CategoryName] || ({CategoryName}) r[CategoryName].Items = [...Items, ...r[CategoryName].Items || []] }, {}) console.log(Object.values(result)) 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.min.js"></script> 

Or simply with just ES6 and Array.reduce :

 let data = [{ CategoryName: 'abc', Items: ['3A'] }, { CategoryName: 'xyz', Items: ['5Z'] }, { CategoryName: 'abc', Items: ['6B'] }, { CategoryName: 'abc', Items: ['9C'] }, { CategoryName: 'xyz', Items: ['1X'] } ]; const result = data.reduce((r,{CategoryName, Items}) => { r[CategoryName] = r[CategoryName] || ({CategoryName}) r[CategoryName].Items = [...Items, ...r[CategoryName].Items || []] return r }, {}) console.log(Object.values(result))