Used in React with use-query-params.

$3

Using npm:

``
$ npm install --save serialize-query-params
`

By default, serialize-query-params uses URLSearchParams to handle interpreting the location string, which means it does not decode null and has limited handling of other more advanced URL parameter configurations. If you want access to those features, add a third-party library like query-string and provide its functions to updateLocation and updateInLocation as needed.

$3

- Param Types
- decodeQueryParams
- encodeQueryParams
- searchStringToObject
- objectToSearchString
- updateLocation
- updateInLocation
- Type Definitions
- Serialization Utility Functions


#### Param Types
See all param definitions here. You can define your own parameter types by creating an object with an encode and a decode function. See the existing definitions for examples.

Note that all null and empty values are typically treated as follows:

| value | encoding |
| --- | --- |
| null | ?foo |
| "" | ?foo= |
| undefined | ? (removed from URL) |

Examples in this table assume query parameter named qp.

| Param | Type | Example Decoded | Example Encoded |
| --- | --- | --- | --- |
| StringParam | string | 'foo' | ?qp=foo |
| NumberParam | number | 123 | ?qp=123 |
| ObjectParam | { key: string } | { foo: 'bar', baz: 'zzz' } | ?qp=foo-bar_baz-zzz |
| ArrayParam | string[] | ['a','b','c'] | ?qp=a&qp=b&qp=c |
| JsonParam | any | { foo: 'bar' } | ?qp=%7B%22foo%22%3A%22bar%22%7D |
| DateParam | Date | Date(2019, 2, 1) | ?qp=2019-03-01 |
| DateTimeParam | Date | Date(2019, 2, 1) | ?qp=2019-02-28T22:00:00.000Z |
| BooleanParam | boolean | true | ?qp=1 |
| NumericObjectParam | { key: number } | { foo: 1, bar: 2 } | ?qp=foo-1_bar-2 |
| DelimitedArrayParam | string[] | ['a','b','c'] | ?qp=a_b_c' |
| DelimitedNumericArrayParam | number[] | [1, 2, 3] | ?qp=1_2_3' |

Enum Param

You can define enum param using createEnumParam. It works as StringParam but restricts decoded output to a list of allowed strings:

`js
import { createEnumParam } from 'serialize-query-params';

// values other than 'asc' or 'desc' will be decoded as undefined
const SortOrderEnumParam = createEnumParam(['asc', 'desc'])
`

Array Enum Param

You can define array enum param using createEnumArrayParam or createEnumDelimitedArrayParam. It will restricts decoded output to a list of allowed values.

`js
import { createEnumArrayParam } from 'serialize-query-params';

// feel free to use Enum instead of union types
type Color = 'red' | 'green' | 'blue'

// values other than 'red', 'green' or 'blue' will be decoded as undefined
const ColorArrayEnumParam = createEnumArrayParam(['red', 'green', 'blue'])
`


Setting a default value

If you'd like to have a default value, you can wrap your param with withDefault():

`js
import { withDefault, ArrayParam } from 'serialize-query-params';

// by default, nulls are converted to defaults
const NeverNullArrayParam = withDefault(ArrayParam, []);

// if you don't want nulls to be included, pass false as a third arg
const NeverUndefinedArrayParam = withDefault(ArrayParam, [], false);
`

Example with Custom Param

You can define your own params if the ones shipped with this package don't work for you. There are included serialization utility functions to make this easier, but you can use whatever you like.

`js
import {
encodeDelimitedArray,
decodeDelimitedArray
} from 'serialize-query-params';

/* Uses a comma to delimit entries. e.g. ['a', 'b'] => qp?=a,b /
const CommaArrayParam = {
encode: (array: string[] | null | undefined): string | undefined =>
encodeDelimitedArray(array, ','),

decode: (arrayStr: string | string[] | null | undefined): string[] | undefined =>
decodeDelimitedArray(arrayStr, ',')
};
`

#### decodeQueryParams

`js
decodeQueryParams(
paramConfigMap: QPCMap,
encodedQuery: Partial>
): DecodedValueMap
`

Convert the values in query from strings to their natural types via the
decode functions configured in paramConfigMap.

Example

`js
import {
stringify,
decodeQueryParams,
NumberParam,
DelimitedArrayParam
} from 'serialize-query-params';

// encode each parameter according to the configuration
const decodedQuery = decodeQueryParams(
{ foo: NumberParam, bar: DelimitedArrayParam },
{ foo: '123', bar: 'a_b' }
);
// produces: { foo: 123, bar: ['a', 'b'] }
`


#### encodeQueryParams

`js
encodeQueryParams(
paramConfigMap: QPCMap,
query: Partial>
): Partial>
`

Convert the values in query to strings via the encode functions configured
in paramConfigMap. This can be useful for constructing links using decoded
query parameters.

Example

`js
import {
encodeQueryParams,
DelimitedArrayParam,
NumberParam,
} from 'serialize-query-params';
import { stringify } from 'query-string';

// encode each parameter according to the configuration
const encodedQuery = encodeQueryParams(
{ foo: NumberParam, bar: DelimitedArrayParam },
{ foo: 123, bar: ['a', 'b'] }
);
// produces: { foo: '123', bar: 'a_b' }

const link = /?${stringify(encodedQuery)};
`

#### searchStringToObject

`js
function searchStringToObject(searchString: string): EncodedQuery
`
Default implementation of searchStringToObject powered by URLSearchParams
This converts a search string like ?foo=123&bar=x to { foo: '123', bar: 'x' }
This is only a very basic version, you may prefer the advanced versions offered
by third party libraries like query-string ("parse") or qs.

Example

`js
import { searchStringToObject } from 'serialize-query-params';

const obj = searchStringToObject('?foo=a&bar=x&foo=z');
// -> { foo: ['a', 'z'], bar: 'x'}
`


#### objectToSearchString

`js
function objectToSearchString(encodedParams: EncodedQuery): string
`

Default implementation of objectToSearchString powered by URLSearchParams.
Does not support null values. Does not prefix with "?"
This converts an object { foo: '123', bar: 'x' } to a search string ?foo=123&bar=x
This is only a very basic version, you may prefer the advanced versions offered
by third party libraries like query-string ("stringify") or qs.

Example

`js
import { objectToSearchString } from 'serialize-query-params';

const obj = objectToSearchString({ foo: ['a', 'z'], bar: 'x' });
// '?foo=a&foo=z&bar=x'
`

#### updateLocation

`js
function updateLocation(
encodedQuery: EncodedQuery,
location: Location,
objectToSearchStringFn = objectToSearchString
): Location {
`

Creates a new location-like object with the new query string (the search field)
based on the encoded query parameters passed in via encodedQuery. Parameters not
specified in encodedQuery will be dropped from the URL.

Example

`js
import { updateLocation } from 'serialize-query-params';

// location has search: ?foo=123&bar=abc
const newLocation = updateLocation({ foo: '555' }, location);

// newLocation has search: ?foo=555
// note that unspecified query parameters (bar in this case) are not retained.
`


#### updateInLocation

`js
function updateInLocation(
encodedQueryReplacements: EncodedQuery,
location: Location,
objectToSearchStringFn = objectToSearchString,
searchStringToObjectFn = searchStringToObject
): Location {
`

Creates a new location-like object with the new query string (the search field)
based on the encoded query parameters passed in via encodedQueryReplacements. Only
parameters specified in encodedQueryReplacements are affected by this update,
all other parameters are retained.

Example

`js
import { updateInLocation } from 'serialize-query-params';

// location has search: ?foo=123&bar=abc
const newLocation = updateLocation({ foo: '555' }, location);

// newLocation has search: ?foo=555&bar=abc
// note that unspecified query parameters (bar in this case) are retained.
`

$3

Run the typescript compiler in watch mode:

`
npm run dev
``