lodash-如何_.filter孩子并从json文件返回所有父母？

Question

I have created route.js file. Based on queryString it has to filter the Json object. When I used _.filter method it returns entire object as response. Actually i want filter that productlist node and include the remaining nodes as response Please Help me .. Thanks in Advance...

Here is the code..

The JSON File

{
    "productList": [
        {
            "productName": "xyz",
            "productType": "mobile"
        },
        {
            "productName": "xyz",
            "productType": "mobile"
        },
        {
            "productName": "xyz",
            "productType": "mobile"
        }
    ],
    "totalProducts": 3,
    "FilteredProducts": 0,
    "test1": 11,
    "test11": 12,
    "test33": 13
}

route.js

var filterByProduct = function(coll, productType){
    return  _.forEach(coll, function(o){
        return _.find(o, function(item){
        });
    });
};
var queryString = function(req, res, next) {
    if (req.query.productType ) {
        var stringObj = JSON.stringify(filterByProduct(jsonFile, req.query.productType),null,4);
        res.end(stringObj);
    } else if (req.query !== {}) {
        var stringObj = JSON.stringify(jsonFile,null,4);
        res.end(stringObj);
    } else {
        res.end('Not a Query String');
    }
}

router.get('/test', queryString, function(req,res){
//
});

Answer 1

The problem here is that the filterByProduct parameter coll isn't bound to the productList array but the top-level object that contains the productList array as well as the other nodes. So you should be targeting coll.productList instead.

Also, using _.filter (on coll.productList ) as you originally mentioned is a better idea than using _.forEach because it iterates through the array and filters the items. Try this version of filterByProduct instead:

var filterByProduct = function(coll, productType){
    return _.filter(coll.productList, function(o) {
        return o.productType === productType;
    })
};

Finally, to return an object similar to your JSON data file that has the filtered version of productList nodes plus the other top-level nodes, you could use the _.clone method to shallow clone your jsonFile object and then overwrite the productList and FilteredProducts properties with the values returned from your filterByProduct function and the length of the results of filterByProduct , respectively. Here's what I came up with:

if (req.query.productType) {
    var stringObj = _.clone(jsonFile);
    stringObj.productList = filterByProduct(jsonFile, req.query.productType);
    stringObj.FilteredProducts = stringObj.productList.length;
    res.end(stringObj);
}