Javascript - 拆分并返回多个数组或字符串中的数组

Question

I have a json like this:

{"search":{"updated":"2018-11-07","name":[{"tag":"Peter"}]}}

... and I dynamically fetch the values and create a variable this:

var existingParams = [
"name",
"updated"].filter(field => getBody.search[field]);

var sqlVal = existingParams.map(field => {
 if (field === 'name') {
     function getValues(item, index) {
       var getVal = [item.tag];
       return "%" + getVal + "%";
     }
     console.log(name.map(getValues));
     return name.map(getValues);

   } else {
     return getBody.search[field];
   }
 })

For the above example I get for sqlVal:

console.log(sqlVal);         

[ [ '%Peter%' ], '2018-11-07' ]

... which is fine.

BUT, if I have two values:

{"search":{"updated":"2018-11-07","name":[{"tag":"Peter"},{"tag":"Jack"}]}} 

... I'm getting this structure:

[ [ '%Peter%', '%Jack%' ], '2018-11-07' ]   

... but what I need is sth like:

[ '%Peter%', '%Jack%', '2018-11-07' ]

... or:

[ ['%Peter%'], ['%Jack%'], '2018-11-07' ]

And in case of further eg 3 names:

{"search":{"updated":"2018-11-07","name":[{"tag":"Peter"},{"tag":"Jack"},{"tag":"Maria"}]}} 

... I need sth like:

[ '%Peter%', '%Jack%', '%Maria%', '2018-11-07' ]        

... or:

[ ['%Peter%'], ['%Jack%'], ['%Maria%'], '2018-11-07' ]

... and so on

How do I need to adjust the above query to get this?

Answer 1

If I understand your question correctly, then this problem can be solved via the Array#reduce() method.

The general idea with this approach is to transform your input object to an array - the reduce operation can be used to do this, with the special-case rule of "flattening" the nested value on the name key into the final result:

 var input = {"search":{"updated":"2018-11-07","name":[{"tag":"Peter"},{"tag":"Jack"}]}} var result = Object .entries(input.search) .reduce(function(result, entry) { const key = entry[0] const value = entry[1] if(key === 'name') { // When the 'name' key is encountered, handle the value // differently, by addting the items of this value array // to the result value.forEach(function(item) { result.push('%' + item.tag + '%') }) } else { // Append values for other keys directly to the result result.push(value) } return result }, []) console.log(result ) 

Answer 2

You could simply use Object.values + reduce for something like this:

 const json = { "search": { "updated": "2018-11-07", "name": [{ "tag": "Peter" }, { "tag": "Jack" }, { "tag": "Maria" }] } } const result = Object.values(json.search).reduce((r,c) => (Array.isArray(c) ? r.push(...c.map(({tag}) => `%${tag}%`)) : r.push(c), r),[]) console.log(result) 

If the order is important (names first then date) you could use reverse :

 const json = { "search": { "updated": "2018-11-07", "name": [{ "tag": "Peter" }, { "tag": "Jack" }, { "tag": "Maria" }] } } const result = Object.values(json.search).reverse().reduce((r,c) => (Array.isArray(c) ? r.push(...c.map(({tag}) => `%${tag}%`)) : r.push(c), r),[]) console.log(result) 

Answer 3

First of all you did not provide a Minimal, Complete, and Verifiable example so it is quite hard for me to figure out where you are running into issues. For example, you are referencing existingParam but nowhere are they defined. This is key to understanding the problem because all of the code that you posted is heavily invested in the values and format of this value.

Second, how are you parsing the JSON? With the standard JSON#parse function you would get back an object with the same structure as your provided JSON. However, you are either not using this or you are mutating the object after it was parsed into a new format. Either way, the object that JSON#parse returns for the provided JSON is not an array and therefor you cannot use Array#map on it.

For the sake of being productive though I am going to try and explain how to do things.

JSON:

let data1 = '{"search":{"updated":"2018-11-07","name":[{"tag":"Peter"}]}}',
    data2 = '{"search":{"updated":"2018-11-07","name":[{"tag":"Peter"},{"tag":"Jack"}]}} ',
    data3 = '{"search":{"updated":"2018-11-07","name":[{"tag":"Peter"},{"tag":"Jack"},{"tag":"Maria"}]}}';

Now that we have our JSON data we need to parse it and store it as a JSON object. To do so I am going to create a function; this way the data can be passed to the same function and handled the same way but the implementation will stay the same. Also, since we are only looking at the values in the search property we are going to go ahead and jump right into it.

Parse the JSON:

function parseResponse (response) {
    let parsedResponse = JSON.parse(response);
        parsedResponse = parsedResponse['search'];
}

Now that we have our function that takes our response and parses it we can then begin to sort through it to find and isolate the parts that we want. In this case we will add some code to loop through our properties and find the updated and name properties.

function parseResponse (response) {
    let parsedResponse = JSON.parse(response);
        parsedResponse = parsedResponse['search'];

    for (let prop in parsedResponse) {
        if (prop === 'updated') {
            // do stuff with 'updated'
        }

        if (prop === 'name') {
            // do stuff with 'name'
        }
    }
}

Because we want to return a result we are going to add a variable updated and names which will hold the values that we pull out of the string until we are ready to return them. Now that we have our loop and our temporary variables we can go ahead and pull the updated value out of our data and place it in the updated variable.

function parseResponse (response) {
    let parsedResponse = JSON.parse(response),
        updated = '',
        names = [];
        parsedResponse = parsedResponse['search'];

    for (let prop in parsedResponse) {
        if (prop === 'updated') {
            updated = parsedResponse[prop];
        }

        if (prop === 'name') {
            // do stuff with 'name'
        }
    }
}

With our updated value squared away we can jump into our names. Since you listed the format ['%name%', '%name%', '%name%'] first I am going to go ahead and show you how to do it this way. Here we are going to grab the property name , iterate through the names, grab the tag property, and then add the % s before pushing it to our names temporary variable.

function parseResponse (response) {
    let parsedResponse = JSON.parse(response),
        updated = '',
        names = [];
        parsedResponse = parsedResponse['search'];

    for (let prop in parsedResponse) {
        if (prop === 'updated') {
            updated = parsedResponse[prop];
        }

        if (prop === 'name') {
            for (let i = 0; i < parsedResponse[prop].length; i++) {
                let name = parsedResponse[prop][i].tag;
                    name = '%' + name + '%';

                names.push(name);
            }
        }
    }
}

With everything in place all that is left is to assemble the result. To do so we are going to flatten the array of names , add them to the array, and then add the updated value to the end before returning it. To flatten the array we are going to use the spread operator.

function parseResponse (response) {
    let parsedResponse = JSON.parse(response),
        updated = '',
        names = [];
        parsedResponse = parsedResponse['search'];

    for (let prop in parsedResponse) {
        if (prop === 'updated') {
            updated = parsedResponse[prop];
        }

        if (prop === 'name') {
            for (let i = 0; i < parsedResponse[prop].length; i++) {
                let name = parsedResponse[prop][i].tag;
                    name = '%' + name + '%';

                names.push(name);
            }
        }
    }

    return [...names, updated];
}

With all of that set we can go ahead and call parseResponse() with data1 , data2 , or data3 and get back a response that looks like so:

let data1 = '{"search":{"updated":"2018-11-07","name":[{"tag":"Peter"}]}}',
    data2 = '{"search":{"updated":"2018-11-07","name":[{"tag":"Peter"},{"tag":"Jack"}]}} ',
    data3 = '{"search":{"updated":"2018-11-07","name":[{"tag":"Peter"},{"tag":"Jack"},{"tag":"Maria"}]}}';

function parseResponse (response) {
    let parsedResponse = JSON.parse(response),
        updated = '',
        names = [];
        parsedResponse = parsedResponse['search'];

    for (let prop in parsedResponse) {
        if (prop === 'updated') {
            updated = parsedResponse[prop];
        }

        if (prop === 'name') {
            for (let i = 0; i < parsedResponse[prop].length; i++) {
                let name = parsedResponse[prop][i].tag;
                    name = '%' + name + '%';

                names.push(name);
            }
        }
    }

    return [...names, updated];
}

console.log(parseResponse(data1));
console.log(parseResponse(data2));
console.log(parseResponse(data3));

Answer 4

Spread operator can be used to flatten the result :

 var obj = {"search":{"updated":"2018-11-07","name":[{"tag":"Peter"},{"tag":"Jack"},{"tag":"Maria"}]}} var arr = [...obj.search.name.map(n => `%${n.tag}%`), obj.search.updated] console.log( arr ) 

---

Another alternative could be to extract during parsing :

 var arr = [], json = '{"search":{"updated":"2018-11-07","name":[{"tag":"Peter"},{"tag":"Jack"},{"tag":"Maria"}]}}' JSON.parse(json, (k, v) => v.trim && arr.push(k === 'tag' ? `%${v}%` : v)) console.log( arr )