Using the switch policy condition editor

The switch policy condition editor provides a user interface to help you build the conditions for the case clauses in a switch policy.

You build a condition script by using the Add Group and Add Condition options, together with operator selections, and pre-supplied function selections. The Output field shows the resultant condition script, and updates dynamically as you build your condition.

Adding conditions

When you open the policy condition editor, an initial condition is pre-supplied ready for you to configure.

Use the drop-down list to select the function that you want to begin your condition.

The following JSONata functions are supported:

Aggregation functions:
- $average(array)
- $max(array)
- $min(array)
- $sum(array)
Array functions:
- $append(array1, array2)
- $count(array)
- $reverse(array)
- $sort(array [, function])
- $zip(array1, ...)
Boolean functions:
- $boolean(arg)
- $exists(arg)
- $not(arg)
Numeric functions:
- $abs(number)
- $ceil(number)
- $floor(number)
- $formatBase(number [, radix])
- $number(arg)
- $power(base, exponent)
- $round(number [, precision])
- $sqrt(number)
Object functions:
- $keys(object)
- $lookup(object, key)
- $merge(array<object>)
- $spread(object)
String functions:
- $contains(str, pattern)
- $join(array[, separator])
- $length(str)
- $lowercase(str)
- $match(str, pattern [, limit])
- $pad(str, width [, char])
- $replace(str, pattern, replacement [, limit])
- $split(str, separator [, limit])
- $string(arg)
- $substring(str, start[, length])
- $substringAfter(str, chars)
- $substringBefore(str, chars)
- $trim(str)
- $uppercase(str)

You can use the following JSONata numeric operators:

+ (addition)
- (subtraction)
* (multiplication)
/ (division)
% (modulo)

You can use the following JSONata comparison operators for number values or strings:

=
!=
<
>
<=
>=

You can also use the following functional extensions to standard JSONata notation. Each extension corresponds to a part of the API context.

Extension	Variable	Description
`$header(name)`	`message.headers.name`	Message header
`$httpVerb()`	`request.verb`	HTTP method of the request
`$operationID()`	`api.operation.id`	ID of the operation
`$operationPath()`	`api.operation.path`	Path of the operation
`$queryParameter('name')`	`request.parameters.name.locations` `request.parameters.name.values`	Returns the value of a request query parameter given the parameter name. The function searches the `request.parameters.name.locations` array for the index position of the value `query`, and returns `request.parameters.name.values[index]`, where `index` is the index position. Parameter values are not URL decoded.
`$statusCode()`	`message.status.code`	Status code
`$storageType([arg])`	`variable.body` You can specify any variable in the API context. When no variable is specified, the default variable `message.body` is used.	Storage type of the message. The supported values are: `binary` `json` `stream` `xml`
`$urlParameter('name')`	`request.parameters.name.locations` `request.parameters.name.values`	Given a request parameter name, returns the parameter values for all occurrences of that parameter as a path parameter or query parameter. The function searches the `request.parameters.name.locations` array for the index positions of the values `path` and `query`, and returns, in a single array, the `request.parameters.name.values[index]` values for all identified index positions. When the URL contains both path and query parameter values, the array includes the path values first followed by the query values. The values of each parameter type are added in the order that they are received. Parameter values are URL decoded. For example, the following URL contains both path and query parameter values: `http://example.com/petstore/cats/adopt?breed=Sphynx&breed=Siamese` The function call `$urlParameter('breed')` returns the following array of values: `[cats, adopt, Sphynx, Siamese]` In this example, the URL includes an API path that is configured as `/petstore/{breed}/{breed}`, where `breed` is configured to be a path parameter of the API path. As a result, `cats` and `adopt` are included in the output.
`$xpath(path, xpathExpression)`	You can specify any writable variable in the API context. The `xpathExpression` must be a literal string.	Allows use of XPath expressions

After you select the function, additional fields are displayed, depending on the selected function, so that you can complete the condition. For example, if you select the function $httpVerb(), a comparison operator selection list is displayed (= or !=), together with a list of HTTP verbs to select on the right hand side of the expression (GET, PUT, POST, DELETE, HEAD, OPTIONS, or PATCH).

If you select NOT, your condition is negated with a $not function.

To add further conditions, click Add Condition; you then select whether to insert an and or an or operator between this condition and the preceding one.

To group two or more conditions inside parentheses, click Add Group, then add your conditions to the group; you then select whether to insert an and or an or operator between this group and the preceding condition or group.

To write your own condition from scratch, select Custom, then enter your script in the field provided.

Example

To build the following condition:

($statusCode() != 200 and ($httpVerb() = 'GET' or $httpVerb() = 'PUT'))

complete these steps in the condition editor:

Select $statusCode(), select != for the comparison operator, and enter 200 in the field on the right hand side of the condition.
Click Add Group.
In the new group sub pane that is displayed, click Add Condition.
Select httpVerb(), leave the comparison operator as =, and select GET on the right hand side of the condition.
Click Add Condition in the group sub pane again.
Select httpVerb(), leave the comparison operator as =, and select PUT on the right hand side of the condition.
For the comparison operator between the two conditions, select or.

Simple condition statements

The following examples show conditions that use a single function.

This example uses the $httpVerb() extension to specify the HTTP method of the request.

$httpVerb()="GET"

This example uses the $operationPath() extension to specify the path of the operation.

$operationPath()="/base/path-2"

This example uses the $operationID() extension to specify the operation ID.

$operationID()="test-gatewayscript-GET"

This example uses the $statusCode() extension to specify the message status code.

$statusCode()=200

This example uses the $header(name) extension to specify the content type of the message header.

$header("Content-Type")="application/json"

Combining conditions with logical operators

You can use and and or operators to combine multiple functions in a single condition.

This example specifies an HTTP GET request and an API operation path equal to test-gatewayscript-GET.

$httpVerb()="GET" and $operationPath()="test-gatewayscript-GET"

This example specifies either a POST or PUT request.

$httpVerb()="POST" or $httpVerb()="PUT"

This example specifies an API operation ID equal to test-gatewayscript_POST and a message status code equal to 200, or an API operation ID equal to test-gatewayscript-GET and a message status code equal to 500.

($operationID()="test-gatewayscript-POST" and $statusCode()=200) or ($operationID()="test-gatewayscript-GET" and $statusCode()=500)

This example specifies an API operation ID equal to test-gatewayscript-POST and a message status code equal to 200 with an API operation path equal to /base/path-2.

($operationID()="test-gatewayscript-POST" and $statusCode()=200) and $operationPath()="/base/path-2"

This example specifies a message header content type equal to text/plain and a message header length equal to 300, or a message status code equal to 200.

($header("Content-Type")="text/plain" and $header("Content-Length")=300) or $statusCode()= 200