RSQL Criteria builder for Typescript


Installation

Install via npm
``bash
npm install rsql-criteria-typescript
`

Usage

Import into the needed files via
`javascript
import { RSQLCriteria, RSQLFilterExpression, Operators } from 'rsql-criteria-typescript';
`

Add your own criteria and call build() to create it!
`javascript
let rsql = new RSQLCriteria();
rsql.filters.and(new RSQLFilterExpression('code', Operators.Equal, 'abc'));
rsql.build()
// returns $where=code=in=%22abc%22 (URL encoded)
`

There are build methods on most things, so feel free to use whatever part you need.

The RSQLCriteria.build() method will generate a query string with the following defaults:
* Filter expressions will be prefixed with $where. ex: $where=code=="abc"
* Order By expressions will be prefixed with $orderBy. ex: $orderBy=code asc, description desc
* Page Size pagination setting will be prefixed with $pageSize. ex: $pageSize=10
* Page Number pagination setting will be prefixed with $pageNumber. ex: $pageNumber=1
* Include Total Count pagination setting will be prefixed with $includeTotalCount. ex: $includeTotalCount=true

These can be overridden by passing in the prefixes you would like when creating the RSQLCriteria object.
`javascript
let rsql = new RSQLCriteria('filterBy', 'order');
`

$3

A filter builder is included as well. You can choose to use this if you prefer this method of constructing
the filter expressions.

`javascript
let builder = new RSQLFilterBuilder();
let list = builder.column('blah').greaterThan(123).toList();
list.build();
// returns blah>123 (URL encoded)
`

Or a more complex example that shows chaining of the expressions:
`javascript
let rsql = new RSQLCriteria();
let builder = new RSQLFilterBuilder();
rsql.filters.and(builder.column('blah').equalTo(123)
.or().column('test').equalTo('abc').toList());
rsql.build();
// returns $where=(blah=in=123 or test=in="abc") (URL encoded)
`

$3


You can add your own Custom Operator if you need as well. An interface of CustomOperator is provided by the library. Create a new class that extends
that interface and implement the convertToRSQLString method. The method is passed the original value, the formatted string value that the library would
use, and the boolean the library uses to know if it should quote a value or not. The quote method is exported for your use as well.
`javascript
export class TestOperator implements CustomOperator {
convertToRSQLString(value: string | number | boolean | (string | number | boolean)[] | Date, valueString: string, shouldQuote: boolean): string {
return "=custom=" + encodeURIComponent(shouldQuote ? quote(valueString) : valueString);
}
}
`
And then you can use it either directly with the RSQLFilterExpression constructor, or with the RSQLFilterBuilder with the custom method.
`javascript
let list = new RSQLFilterBuilder()
.column('blah')
.custom(new TestOperator(), "support")
.toList();
//returns blah=custom="support" (URL encoded)
`

$3

You can combine multiple RSQLCriteria instances by the and or or functions that are available. The major thing to know about this is that the criteria that you call and or or on will be the one that the pagination and order by parts will be taken from. The combination is a way to combine the filters together in a nice fashion.
`javascript
let criteria1 = new RSQLCriteria();
criteria1.pageSize = 10;
let criteria2 = new RSQLCriteria();
criteria2.pageSize = 5;
criteria1.and(criteria2);
criteria1.build();
// returns $pageSize=10 instead of pageSize = 5
`

$3

An optional RSQLBuildOptions object can be passed into each of the build() methods to change the behavior of how the strings get built.
#### encodeString
encodeString can be used to chose whether or not you want the results to be encoded or not. By default the library WILL encode the resulting string, but if you pass in {encodeString: false} to the build() method, then the results will not be encoded. Example:
`javascript
const builder: RSQLFilter = new RSQLFilterBuilder();
const list = builder
.column('blah').equalTo('123')
.and().column('name').equalTo('John')
.toList();
expect(list.build()).toEqual(
(blah=in=%22123%22%20and%20name=in=%22John%22)
);
expect(list.build({encodeString: false})).toEqual(
(blah=in="123" and name=in="John")
);
`

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This library has been tested against a SQL Server backend and some irregularities have been found. A RSQL == operation turns into a LIKE in SQL Server so that wildcard characters are available for use. However, in most other languages an equals operation is an exact match. To handle this, the Operators.Equal and RSQLFilterBuilder.equalTo methods will create an =in= RSQL string. This doesn't allow wildcards to be used in and will intuitively make more sense for those of us that are used to equals meaning exactly equal to. Wildcard characters are still allowed to be passed in, but they will be interpreted as the characters themselves and not wildcards.

To allow wildcards to be used, another operation and function are available. Operators.Like and RSQLFilterBuilder.like will use the RSQL ==` and allow wildcard characters to be passed along.

$3

Other examples can be found in the tests folder. Many usages already have tests wrapped around them.

Acknowledgements

Created with Typescript Library Starter