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.

JSONata support in API Connect

API Connect supports v2.0 of the JSONata specification, with the following limitations:

If you use a JSONata expression to extract or redact fields, soft linked copies of the field are also affected by the Extract or Redaction policy, even if the fields exist in different locations.
API Connect does not support higher order JSONata functions (functions that process other functions).
If a JSONata function supported by API Connect calls a higher order function as an argument, that argument is not supported (due to the lack of support for higher order functions).
The following JSONata v2.0 functions are not supported:
- $eval()
- $formatNumber()
- $formatInteger()
- $parseInteger()
- $sift()
- $each()
- $error()
- $assert()
- $fromMillis()
$now() is supported with the following restrictions:
- The following component specifiers are not supported:
  - W = Week in year
  - w = Week in month
  - X = ISO week-numbering year
  - x = ISO week-numbering month
- Representing numbers as words are not supported, so the following presentation modifiers are not supported:
  - W = Uppercase word (for example: [YW] => TWO THOUSAND AND TWENTY-FOUR)
  - w = Lowercase word (for example: [Yw] => two thousand and twenty-four)
  - Ww = Title case word (for example: [YWw] => Two Thousand and Twenty-Four)
- Error messages are generic.

Table 1 lists the functional extensions that you can use with standard JSONata notation. Each extension corresponds to a part of the API context.

Table 1. Functional extensions to JSONata
Extension	Variable	Description
`$apiCtx()`	Generic access to an API context	The `$apiCtx()` extension gives generic access to an API context. Sample transform field in an extract action: `"$apiCtx().request.uri"` Sample condition of a case in a switch action: `"$apiCtx().request.path = '/simple/apictx-function'"`
`$header(name)`	`message.headers.name`	Message header
`$httpVerb()`	`request.verb`	HTTP method of the request
`$operationID()`	`api.operation.id`	ID of the operation
`$operationPath()`	`api.operation.path`	Path of the operation
`$queryParameter('name')`	`request.parameters.name.locations` The supported keyword is `query`. `request.parameters.name.values`	Searches for the index of `query` in `request.parameters.name.locations` and returns `request.parameters.name.values[index]`, where `[index]` is the value for `query` in locations. Parameter values are not URL decoded.
`$statusCode()`	`message.status.code`	Status code
`$storageType([arg])`	`variable.body` You can specify any variable in the API context. When no variable is specified, the default variable `message.body` is used.	Storage type of the message. The supported values are `binary`, `empty`, `graphql`, `json`, `stream`, or `xml`.
`$urlParameter('name')`	`request.parameters.name.locations` The supported keywords are `path` and `query` `request.parameters.name.values`	Searches for the index of `path` and `query` in `request.parameters.name.locations` and returns a single array that contains both `path` and `query` values from `request.parameters.name.values`. 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 `$urlParameter('breed')` URL returns the following array of values. `[cats, adopt, Sphynx, Siamese]` In this example, the URL includes an API path that is configured as `/petstore/{breed}/{breed}`, where `breed` is configured to be a path parameter of the API path. As a result, `cats` and `adopt` are included in the output.
`$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. The following example specifies all price elements in the source. `$xpath($, '//price')`

Table 2 lists the functional extensions that you can use with GraphQL APIs.

Table 2. Functional extensions to JSONata for GraphQL
Extension	Variable	Description
`$gqlActiveOperation([graphql_message])`	`message.body`	Gets the active operation found in the specified GraphQL message. The `operationName` must be the same as the name of the active operation.
`$gqlAlias(graphql_field_node)`	`message.body`	Gets the alias of a GraphQL field node.
`$gqlFragments([graphql_message])`	`message.body`	Gets the fragments found in the specified GraphQL message.
`$gqlName([graphql_node])`	`message.body`	Gets the node name. For operations, the node name is the `operationName`. For fields, fragment definitions, arguments, and other elements, the node name is the name of the element. By default, the `operationName` of `message.body` is retrieved.
`$gqlOperations([graphql_message])`	`message.body`	Gets the operations found in the specified GraphQL message.
`$gqlType([graphql_node])`	`message.body`	The operation type of the active operation is retrieved for Query, Mutation, and Subscription query types.

In addition to the functional extensions, you can use the following operators:

You can use the & (concatenation) navigation operator.

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 operators and expressions.

Parentheses to convert a sequence into an array, specify operator precedence, or compute complex expressions on a context value.
Array ranges and predicate expressions.
Single asterisk (*) and double asterisk (**) wildcard characters.

The following elements of a GraphQL query can be exposed in JSONata notation using the syntax shown.

query
The entire GraphQL query including operations and fragments.
operationName
For an anonymous operation, operationName can be empty.
~fragmentSpreadName
on~typeCondition
~~fragmentDefinitionName

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