I want to encode a complex json/javascript object into the standard querystring encoding. And i want to decode this querystring back to an json/javascript object. It should be recursively, with arrays, objects, strings, booleans and numbers.
I thought this should be easy, but was proven wrong. Does anyone have an idea, how to solve this problem? Either in Javascript or preferably in Typescript.
I think, what you want to do, is encode and decode nested objects.
There is no single standard, but very often, QS (Query String) syntax is used:
{
"attribute": "value",
"array": ["apples", "bananas"],
"object": { "number": 55 },
}
will become:
?attribute=value&array[0]=apples&array[1]=bananas&object[number]=55
Example code:
function decode(querystring: string): object {
function parseValue(value: string): any {
if (value === 'TRUE') return true;
if (value === 'FALSE') return false;
return isNaN(Number(value)) ? value : Number(value);
}
function dec(list: any[], isArray = false): object {
let obj: any = isArray ? [] : {};
let recs: any[] = list.filter((item) => {
if (item.keys.length > 1) return true;
obj[item.keys[0]] = parseValue(item.value);
});
let attrs = {};
recs.map((item) => {
item.key = item.keys.shift();
attrs[item.key] = [];
return item;
}).forEach((item) => attrs[item.key].push(item));
Object.keys(attrs).forEach((attr) => {
let nextKey = attrs[attr][0].keys[0];
obj[attr] = dec(attrs[attr], typeof nextKey === 'number');
});
return obj;
}
return dec(
querystring
.split('&')
.map((item) => item.split('=').map((x) => decodeURIComponent(x)))
.map((item) => {
return {
keys: item[0]
.split(/[\[\]]/g)
.filter((n) => n)
.map((key) => (isNaN(Number(key)) ? key : Number(key))),
value: item[1],
};
})
);
}
export function encode(object: object): string {
function reducer(obj, parentPrefix = null) {
return function (prev, key) {
const val = obj[key];
key = encodeURIComponent(key);
const prefix = parentPrefix ? `${parentPrefix}[${key}]` : key;
if (val == null || typeof val === 'function') {
prev.push(`${prefix}=`);
return prev;
}
if (typeof val === 'boolean') {
prev.push(`${prefix}=${val.toString().toUpperCase()}`);
return prev;
}
if (['number', 'string'].includes(typeof val)) {
prev.push(`${prefix}=${encodeURIComponent(val)}`);
return prev;
}
prev.push(
Object.keys(val).reduce(reducer(val, prefix), []).join('&')
);
return prev;
};
}
return Object.keys(object).reduce(reducer(object), []).join('&');
}
const obj = { key: 1, key1: 2, key2: 3 }
const params = encodeURIComponent(JSON.stringify(obj))
window.location.href = `http://example.com/?query=${params}`
end like this:
http://example.com/?query=%7B%22key%22%3A1%2C%22key1%22%3A2%2C%22key2%22%3A3%7D