如何读取 json 文件并过滤结果

Question

I am stacked since 7 days in a simple function in javascript... but i can not find the soluction!

The problem is this: I have to read a json file, and filter the result...

This is my server-side script for read the file:

function testing(email) 
{
    let rawdata = fs.readFileSync('test.json');
    var mydata = JSON.parse(rawdata);
    console.log("parse:"+ mydata);

    const value = email;
    const result = mydata.filter(email);
    console.log("result: " + result);

    if(result == 'undefined')
    {
        return(false);
    }
    else
    {
        return(true);
    }
};

This is my json file:

[
{
    "1":"black@gmail.com"
},
{
    "2":"bad@gmail.com"
}
{
    "3":"strangemail@gmail.com"
}
]

Answer 1

That JSON data structure is rather odd, with a different key in each object, but if that's what you're stuck with, here's how it can be handled.

 // a string to stand in for JSON fie: const jsonStr = `[ {"1":"black@gmail.com"}, {"2":"bad@gmail.com"}, {"3":"strangemail@gmail.com"} ]`; function testing(email) { var mydata = JSON.parse(jsonStr); const result = mydata.filter(obj => { // search every property in object for email, since the // source JSON data doesn't have consistent keys for (let [key, value] of Object.entries(obj)) { if (value === email) { return true; } } }); console.log(result); // [ { '2': 'bad@gmail.com' } ] return result.length > 0; } let example = testing("bad@gmail.com"); console.log(example); // true

Answer 2

Every element of json array should contain the same consistent key and if you need index, index should be another key ie: const myData = [{"idx": 1, "email": "black@gmail.com"}, {"idx": 2, "email": "bad@gmail.com"}, {"idx": 3, "email": "strangemail@gmail.com"}]

And then you could filter data using the expression as

const result = myData.filter((x) => x.email === email);

Result should be something like:

[{"idx": 1, "email": "black@gmail.com"}]