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A querystring parser with nesting support

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qs

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A querystring parsing and stringifying library.

The idea for Java qs module comes from js qs

Gradle dependencies

maven { url 'https://jitpack.io' }

implementation 'com.github.qianshui423:qs:1.0.0'

Different from js qs

PlainObjects is supported by default. 'plainObjects', 'allowPrototypes' and 'delimiter' parameter are not supported when parsing .

UTF-8 is supported by default. Can't support set other charset when parsing or stringify.

Can't support set 'indices' when stringify. I think that the parameter is conflict with arrayFormat's 'repeat'.

Can't support skip add element for arrayFormat's 'indices' when parsing.

Can't support set 'arrayLimit' when parsing. the implementation way does not need to rely on this.

Can't support custom encoder when parsing or stringify.

Remark

To make the document clearer, the examples are pseudo code.

Usage

Test Case: UsageTest

Parse

QSObject qsObject = QS.parse('a=c');

Stringify

qsObject.toQString();
// or
QS.toQString(qsObject);

Parsing Objects

Test Case: ParsingObjectsTest

parser.parse(string, [ParseOptions]);

qs allows you to create nested objects within your query strings, by surrounding the name of sub-keys with square brackets []. For example, the string 'foo[bar]=baz' converts to:

QS.parse('foo[bar]=baz');

{
    foo: {
        bar: 'baz'
    }
}

URI encoded strings work too:

QS.parse('a%5Bb%5D=c');

{
    a: { b: 'c' }
}

You can also nest your objects, like 'foo[bar][baz]=foobarbaz':

QS.parse('foo[bar][baz]=foobarbaz');

{
    foo: {
        bar: {
            baz: 'foobarbaz'
        }
    }
}

By default, when nesting objects qs will only parse up to 5 children deep. This means if you attempt to parse a string like 'a[b][c][d][e][f][g][h][i]=j' your resulting object will be:

QS.parse('a[b][c][d][e][f][g][h][i]=j');

{
    a: {
        b: {
            c: {
                d: {
                    e: {
                        f: {
                            '[g][h][i]': 'j'
                        }
                    }
                }
            }
        }
    }
}

This depth can be overridden by passing a depth option to qs.parse(string, [options]):

QS.parse('a[b][c][d][e][f][g][h][i]=j', new ParseOptions.Builder().setDepth(1).build());

{ a: { b: { '[c][d][e][f][g][h][i]': 'j' } } }

The depth limit helps mitigate abuse when qs is used to parse user input, and it is recommended to keep it a reasonably small number.

For similar reasons, by default qs will only parse up to 1000 parameters. This can be overridden by passing a parameterLimit option:

QS.parse('a=b&c=d', new ParseOptions.Builder().setParameterLimit(1).build());

{ a: 'b' }

To bypass the leading question mark, use ignoreQueryPrefix:

QS.parse('?a=b&c=d', new ParseOptions.Builder().setIgnoreQueryPrefix(true).build());

{ a: 'b', c: 'd' }

Option allowDots can be used to enable dot notation:

QS.parse('a.b=c', new ParseOptions.Builder().setAllowDots(true).build());

{ a: { b: 'c' } }

Parsing Arrays

Test Case: ParsingArraysTest

qs can also parse arrays using a similar [] notation:

QS.parse('a[]=b&a[]=c');

{ a: ['b', 'c'] }

You may specify an index as well:

QS.parse('a[0]=c&a[1]=b');

{ a: ['b', 'c'] }

Note that an empty string is also a value, and will be preserved:

QS.parse('a[]=&a[]=b');

{ a: ['', 'b'] }
QS.parse('a[0]=b&a[1]=&a[2]=c');

{ a: ['b', '', 'c'] }

To disable array parsing entirely, set parseArrays to false.

QS.parse('a[]=b', new ParseOptions.Builder().setParseArrays(false).build());

{ a: { '0': 'b' } }

If you mix notations, qs will merge the two items into an object:

QS.parse('a[0]=b&a[b]=c');

{ a: { '0': 'b', b: 'c' } }

You can also create arrays of objects:

QS.parse('a[][b]=c');

{ a: [{ b: 'c' }] }

Some people use comma to join array, qs can parse it:

QS.parse('a=b,c', new ParseOptions.Builder().setComma(true).build());

{ a: ['b', 'c'] }

(this cannot convert nested objects, such as a={b:1},{c:d})

Stringifying

Test Case: StringifyingTest

QS.toQString(object, [options]);

When stringifying, qs by default URI encodes output. Objects are stringified as you would expect:

ObjectEqual.equals(QS.toQString({ a: 'b' }), 'a=b');
ObjectEqual.equals(QS.toQString({ a: { b: 'c' } }), 'a%5Bb%5D=c');

This encoding can be disabled by setting the encode option to false:

ObjectEqual.equals(QS.toQString({ a: { b: 'c' } }, new StringifyOptions.Builder().setEncode(false).build()), 'a[b]=c');

Encoding can be disabled for keys by setting the encodeValuesOnly option to true:

ObjectEqual.equals(encodeValuesOnlyObject.toQString({ a: 'b', c: ['d', 'e=f'], f: [['g'], ['h']] }, new StringifyOptions.Builder().setEncodeValuesOnly(true).build()), 'a=b&c[0]=d&c[1]=e%3Df&f[0][0]=g&f[1][0]=h');

When arrays are stringified, by default they are given explicit indices:

ObjectEqual.equals(QS.toQString({ a: ['b', 'c', 'd'] }, new StringifyOptions.Builder().setEncode(false).build()), 'a[0]=b&a[1]=c&a[2]=d');

You may use the arrayFormat option to specify the format of the output array:

ObjectEqual.equals(QS.toQString({ a: ['b', 'c'] }, new StringifyOptions.Builder().setEncode(false).setArrayFormat(ArrayFormat.INDICES).build()), 'a[0]=b&a[1]=c');
ObjectEqual.equals(QS.toQString({ a: ['b', 'c'] }, new StringifyOptions.Builder().setEncode(false).setArrayFormat(ArrayFormat.BRACKETS).build()), 'a[]=b&a[]=c');
ObjectEqual.equals(QS.toQString({ a: ['b', 'c'] }, new StringifyOptions.Builder().setEncode(false).setArrayFormat(ArrayFormat.REPEAT).build()), 'a=b&a=c');
ObjectEqual.equals(QS.toQString({ a: ['b', 'c'] }, new StringifyOptions.Builder().setEncode(false).setArrayFormat(ArrayFormat.COMMA).build()), 'a=b,c');

When objects are stringified, by default they use bracket notation:

ObjectEqual.equals(QS.toQString({ a: { b: { c: 'd', e: 'f' } } }, new StringifyOptions.Builder().setEncode(false).build()), 'a[b][c]=d&a[b][e]=f');

You may override this to use dot notation by setting the allowDots option to true:

ObjectEqual.equals(QS.toQString({ a: { b: { c: 'd', e: 'f' } } }, new StringifyOptions.Builder().setEncode(false).setAllowDots(true).build()), 'a.b.c=d&a.b.e=f');

Empty strings and null values will omit the value, but the equals sign (=) remains in place:

ObjectEqual.equals(QS.toQString({ a: '' }), 'a=');

Key with no values (such as an empty object or array) will return nothing:

ObjectEqual.equals(QS.toQString({ a: [] }), '');
ObjectEqual.equals(QS.toQString({ a: {} }), '');
ObjectEqual.equals(QS.toQString({ a: [{}] }), '');
ObjectEqual.equals(QS.toQString({ a: { b: []} }), '');
ObjectEqual.equals(QS.toQString({ a: { b: {}} }), '');

The query string may optionally be prepended with a question mark:

ObjectEqual.equals(QS.toQString({ a: 'b', c: 'd' }, new StringifyOptions.Builder().setAddQueryPrefix(true).build()), '?a=b&c=d');

Handling of null values

Test Case: HandlingNullTest

By default, null values are treated like empty strings:

ObjectEqual.equals(QS.toQString({ a: null, b: '' }), 'a=&b=');

Parsing does not distinguish between parameters with and without equal signs. Both are converted to empty strings.

ObjectEqual.equals(QS.parse('a&b='), { a: '', b: '' });

To distinguish between null values and empty strings use the strictNullHandling flag. In the result string the null values have no = sign:

ObjectEqual.equals(QS.toQString({ a: null, b: '' }, new StringifyOptions.Builder().setStrictNullHandling(true).build()), 'a&b=');

To parse values without = back to null use the strictNullHandling flag:

ObjectEqual.equals(QS.parse('a&b=', new ParseOptions.Builder().setStrictNullHandling(true).build()), { a: null, b: '' });

To completely skip rendering keys with null values, use the skipNulls flag:

ObjectEqual.equals(QS.toQString({ a: 'b', c: null}, new StringifyOptions.Builder().setSkipNulls(true).build()), 'a=b');

License 📄

Copyright 2019 qianshui423

Licensed under the Apache License, Version 2.0 (the "License");you may not use this file except in compliance with the License.You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.See the License for the specific language governing permissions and limitations under the License.

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