我有以下对象 records
:
{
"notes":[
{
"id":1,
"description":"hey",
"userId":2,
"replyToId":null,
"postId":2,
"parentId":null
},
{
"id":5,
"description":"hey test",
"userId":3,
"replyToId":null,
"postId":2,
"parentId":null
},
{
"id":2,
"description":"how are you",
"userId":null,
"replyToId":2,
"postId":2,
"parentId":null,
"user":null
}
]
}
我想把它输出为。
2
object with id 1
object with id 2 (because replyToId value is same as userId
3
object with id 5
所以基本上我想把UserId和replyToId的值放在同一个组里。
我在lodash下建立了自己的mixin,把groupBy方法包装成。
mixin({
splitGroupBy: function(list, groupByIter){
if (_.isArray(groupByIter)) {
function groupBy(obj) {
return _.forEach(groupByIter, function (key){
if ( !!obj[key] ) return obj[key]
});
}
} else {
var groupBy = groupByIter;
}
debugger;
var groups = _.groupBy(list, groupBy);
return groups;
}
});
调用是这样的
_.splitGroupBy(data.notes,['userId', 'replyToId']);
输出没有分组。即使我已经尝试与 _.map
而是 _.forEach
分割不能正确进行。
使用下划线的解决方案。
var props = ['userId', 'replyToId'];
var notNull = _.negate(_.isNull);
var groups = _.groupBy(record.notes, function(note){
return _.find(_.pick(note, props), notNull);
});
这也许可以做得更漂亮,但应该可以用。
lodash.mixin({
splitGroupBy: function(list, groupByIter) {
var _ = this, groupBy;
if (lodash.isArray(groupByIter)) {
groupBy = function(obj) {
return _(obj) .pick(groupByIter)
.values()
.without(null, undefined)
.first();
};
} else {
groupBy = groupByIter;
}
var groups = _.groupBy(list, groupBy);
return groups;
}
});
你可以把你的属性列表映射到它们各自的值上 然后选取第一个非伪造的值作为你的组键:
_.mixin({
splitGroupBy: function(list, groupByIter){
if (!_.isArray(groupByIter))
return _.groupBy(list, groupByIter);
return _.groupBy(list, function(o) {
var values = _.map(groupByIter, function(k) {
return o[k];
});
return _.find(values);
});
}
});
var data = {
"notes":[
{
"id":1,
"userId":2,
"replyToId":null
},
{
"id":5,
"userId":3,
"replyToId":null
},
{
"id":2,
"userId":null,
"replyToId":2
}
]
};
_.mixin({
splitGroupBy: function(list, groupByIter){
if (!_.isArray(groupByIter))
return _.groupBy(list, groupByIter);
return _.groupBy(list, function(o) {
var values = _.map(groupByIter, function(k) {
return o[k];
});
return _.find(values);
});
}
});
snippet.log(JSON.stringify(_.splitGroupBy(data.notes,['userId', 'replyToId'])));
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假设... userId
和 replyToId
是相互排斥的(即你要么有一个 userId
或 replyToId
但绝不是两者都有),因为它们在样本数据中,然后指定一个自定义分组函数就可以了。
_.groupBy(data.notes, function(note) {
return note.userId || note.replyToId;
});
你可以使用stringify对象作为键。
_.groupBy(notes, ({ userId, replyToId }) => JSON.stringify({ userId, replyToId }));
输出。
{
"{\"userId\":2,\"replyToId\":null}": [
{
"id": 1,
"description": "hey",
"userId": 2,
"replyToId": null,
"postId": 2,
"parentId": null
}
],
"{\"userId\":3,\"replyToId\":null}": [
{
"id": 5,
"description": "hey test",
"userId": 3,
"replyToId": null,
"postId": 2,
"parentId": null
}
],
"{\"userId\":null,\"replyToId\":2}": [
{
"id": 2,
"description": "how are you",
"userId": null,
"replyToId": 2,
"postId": 2,
"parentId": null,
"user": null
}
]
}