prop-extractor
v1.0.1
Published
Get values from complicated data structures, nested arrays and objects, using request string like 'foo.[].bar.[].baz'.
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Readme
Contents
- Creating Extractor instance and test data
- Getting single values
2.1. ... if path exists
2.2. ... if path doesn't exist
2.3. ... with checking of path existence - Getting arrays of values
3.1. ... if path exists
3.2. ... if path doesn't exist
3.3. ... with checking of path existence - More examples
4.1. Getting of array elements
4.2. Getting a defined property of array elements (objects)
4.3. Getting a defined property of array elements (objects) that are deeply nested - Using filters
5.1. Getting names of countries with population bigger than 300 millions
5.2. Getting names of cities where name starts with ‘S’
5.3. Getting cities with population bigger than 20 millions in countries with population bigger than 1 billion
1. Creating Extractor instance and test data
const Extractor = require('prop-extractor');
let extractor = new Extractor();
let data = {
countries: [
{
name: 'Australia',
population: 24641662,
cities: [
{name: 'Sydney', population: 5029768},
{name: 'Melbourne', population: 4725316},
{name: 'Canberra', population: 435019}
]
},
{
name: 'Brazil',
population: 211243220,
cities: [
{name: 'São Paulo', population: 12038175},
{name: 'Rio de Janeiro', population: 6498837},
{name: 'Salvador', population: 2938092}
]
},
{
name: 'China',
population: 1388232693,
cities: [
{name: 'Shanghai', population: 24152700},
{name: 'Beijing', population: 21700000},
{name: 'Guangzhou', population: 14043500}
]
},
{
name: 'United States',
population: 326474013,
cities: [
{name: 'New York', population: 8537673},
{name: 'Los Angeles', population: 3976322},
{name: 'Chicago', population: 2704958}
]
}
],
country_codes: ['AU', 'BR', 'CN', 'US'],
count: 4
};
2. Getting single values
2.1. ... if path exists
extractor.setPath('data.count');
console.log(extractor.extractFrom(data).get());
// 4
2.2. ... if path doesn't exist
extractor.setPath('data.foo.bar.baz');
console.log(extractor.extractFrom(data).get());
// undefined
2.3. ... with checking of path existence
extractor.setPath('data.count');
let response = extractor.extractFrom(data);
if (response.has()) {
console.log(response.get());
}
// 4
3. Getting arrays of values
3.1. ... if path exists
extractor.setPath('data.country_codes.[]');
console.log(extractor.extractFrom(data).get());
// ['AU', 'BR', 'CN', 'US']
3.2. ... if path doesn't exist
extractor.setPath('data.foo.[].bar');
console.log(extractor.extractFrom(data).get());
// []
3.3. ... with checking of path existence
extractor.setPath('data.country_codes.[]');
response = extractor.extractFrom(data);
if (response.has()) {
console.log(response.get());
}
// ['AU', 'BR', 'CN', 'US']
4. More examples
4.1. Getting of array elements
extractor.setPath('data.countries.[]');
console.log(extractor.extractFrom(data).get());
// [ { name: 'Australia', population: 24641662, cities: [ ... ] },
// { name: 'Brazil', population: 211243220, cities: [ ... ] },
// { name: 'China', population: 1388232693, cities: [ ... ] },
// { name: 'United States', population: 326474013, cities: [ ... ] } ]
4.2. Getting a defined property of array elements (objects)
extractor.setPath('data.countries.[].name');
console.log(extractor.extractFrom(data).get());
// [ 'Australia', 'Brazil', 'China', 'United States' ]
4.3. Getting a defined property of array elements (objects) that are deeply nested
extractor.setPath('data.countries.[].cities.[].name');
console.log(extractor.extractFrom(data).get());
// [ 'Sydney', 'Melbourne', 'Canberra', 'São Paulo',
// 'Rio de Janeiro', 'Salvador', 'Shanghai', 'Beijing',
// 'Guangzhou', 'New York', 'Los Angeles', 'Chicago' ]
5. Using filters
5.1. Getting names of countries with population bigger than 300 millions
extractor.setPath('data.countries.[population].name');
extractor.removeAllFilters();
extractor.setFilter('population', (item) => {
return (item.population > 300000000);
});
console.log(extractor.extractFrom(data).get());
// [ 'China', 'United States' ]
5.2. Getting names of cities where name starts with 'S'
extractor.setPath('data.countries.[].cities.[city_name].name');
extractor.removeAllFilters();
extractor.setFilter('city_name', (item) => {
return (item.name[0] === 'S');
});
console.log(extractor.extractFrom(data).get());
// [ 'Sydney', 'São Paulo', 'Salvador', 'Shanghai' ]
5.3. Getting cities with population bigger than 20 millions in countries with population bigger than 1 billion
extractor.setPath('data.countries.[country_population].cities.[city_population]');
extractor.removeAllFilters();
extractor.setFilter('country_population', (item) => {
return (item.population > 1000000000);
});
extractor.setFilter('city_population', (item) => {
return (item.population > 20000000);
});
console.log(extractor.extractFrom(data).get());
// [ { name: 'Shanghai', population: 24152700 },
// { name: 'Beijing', population: 21700000 } ]