$filter

Allows to query the data in a dataclass or method (e.g., $filter="firstName!='' AND salary>30000")

Description

This parameter allows you to define the filter for your dataclass or method.

Using a simple filter

A filter is composed of the following elements:

{attribute} {comparator} {value}

For example: $filter="firstName=john" where firstName is the attribute, = is the comparator and john is the value.

Using a complex filter

A more compex filter is composed of the following elements, which joins two queries:

{attribute} {comparator} {value} {AND/OR/EXCEPT} {attribute} {comparator} {value}

For example: $filter="firstName=john AND salary>20000" where firstName and salary are attributes in the Employee dataclass.

Using the params property

You can also use 4D's params property.

{attribute} {comparator} {placeholder} {AND/OR/EXCEPT} {attribute} {comparator} {placeholder}&$params='["{value1}","{value2}"]"'

For example: $filter="firstName=:1 AND salary>:2"&$params='["john",20000]' where firstName and salary are attributes in the Employee dataclass.

For more information regarding how to query data in 4D, refer to the dataClass.query() documentation.

When inserting quotes (') or double quotes ("), you must escape them using using their character code:

Quotes ('): \u0027 Double quotes ("): \u0022

For example, you can write the following when passing a value with a quote when using the params property:
http://127.0.0.1:8081/rest/Person/?$filter="lastName=:1"&$params='["O\u0027Reilly"]'

If you pass the value directly, you can write the following: http://127.0.0.1:8081/rest/Person/?$filter="lastName=O'Reilly"

Attribute

If the attribute is in the same dataclass, you can just pass it directly (e.g., firstName). However, if you want to query another dataclass, you must include the relation attribute name plus the attribute name, i.e. the path (e.g., employer.name). The attribute name is case-sensitive (firstName is not equal to FirstName).

You can also query attributes of type Object by using dot-notation. For example, if you have an attribute whose name is "objAttribute" with the following structure:

{
    prop1: "this is my first property",
    prop2: 9181,
    prop3: ["abc","def","ghi"]
}

You can search in the object by writing the following:

GET /rest/Person/?filter="objAttribute.prop2 == 9181"

Comparator

The comparator must be one of the following values:

Comparator	Description
=	equals to
!=	not equal to
>	greater than
>=	greater than or equal to
<	less than
<=	less than or equal to
begin	begins with

Examples

In the following example, we look for all employees whose last name begins with a "j":

 GET  /rest/Employee?$filter="lastName begin j"

In this example, we search the Employee dataclass for all employees whose salary is greater than 20,000 and who do not work for a company named Acme:

 GET  /rest/Employee?$filter="salary>20000 AND  
 employer.name!=acme"&$orderby="lastName,firstName"

In this example, we search the Person dataclass for all the people whose number property in the anotherobj attribute of type Object is greater than 50:

 GET  /rest/Person/?filter="anotherobj.mynum > 50"