Variable references in API Connect

Types of variables

Methods of referencing variables

GatewayScript references

When you want to reference a variable in a GatewayScript context, use one of the following methods:

apim.getvariable(variable)

where variable is the name of the context variable or API property that you want to reference.

apim.setvariable(variable, value, action)

where

• variable is the name of the context variable or API property that you want to reference.
• value is the string value that you want to set the variable to. This can be a literal value, or another variable. For example, to set your named variable to the value of the Content-Type header in a request, use the following code:

  var contentType = apim.getvariable('request.headers.content-type');
  apim.setvariable(variable, contentType, 'set');

  This property is required only when set or add is specified as the action.
• action is the action that you want to apply to the variable. Valid options are:
  • set
  • add
  • clear
  If no option is set, the default option of set is applied.

Use the getvariable method to retrieve the value of a context variable or API property, and the setvariable method to change one.

Some of the situations where you would use this type of reference are:

• GatewayScript policies. -For more information, see GatewayScript.
• if logic constructs. For more information, see if.
• User-defined policies. For more information, see Authoring policies.

Stylesheet references

You can reference a variable by using functions and elements in an XSLT policy with the following syntax:

<xsl:variable name="variable_name" select="apim:getVariable(variable)" />

where variable is a literal value, another variable, or a valid XSLT XPath statement.

<xsl:call-template name="apim:setVariable"> 
    <xsl:with-param name="varName" select="variable"/>
    <xsl:with-param name="value" select="value"/>
    <xsl:with-param name="action" select="action"/>
</xsl:call-template> 

where

• variable is the name of the context variable or API property that you want to reference. This can be a literal value, another variable, or a valid XSLT XPath statement.
• value is the string value that you want to set the variable to. This can be a literal value, another variable, or a valid XSLT XPath statement. This property is required only when set or add is specified as the action.
• action is the action that you want to apply to the variable. This can be a literal value, another variable, or a valid XSLT XPath statement. Valid options are:
  • set
  • add
  • clear
  If no option is set, the default option of set is applied.

The following example sets a named variable to the value of the Content-Type header in a request:

<xsl:variable name="contentType" select="apim:getVariable('request.headers.content-type')" />
<xsl:call-template name="apim:setVariable"> 
    <xsl:with-param name="varName" select="'variable'"/>
    <xsl:with-param name="value" select="$contentType"/>
    <xsl:with-param name="action" select="'set'"/>
</xsl:call-template>

Inline references

In many situations you can make a simpler reference, by using the following syntax:

$(variable)

where variable is the name of the context variable or API property that you want to reference.

Some of the situations where you would use this type of reference are:

• The URL called by an Invoke or Proxy policy. For more information about the policies, see Invoke or Proxy.
• A Map policy. For more information, see Map.

Notes: The map policy can reference the following variables inline:

• Variables that are defined as inputs to the map policy and specified in the from field of a mapping.
• Context variable or API properties, provided that the x-ibm-gateway-map-resolve-apic-variables API property is not set to false. If an inline reference in a map policy resolves to a context variable or API property, it is immediately replaced by the corresponding value. For more information on the x-ibm-gateway-map-resolve-apic-variables API property, see Properties controlling the map policy.

For more information on the use of inline references, and examples, see the following About inline references section.

About inline references

curl --data-binary @request.json \
   -H 'Content-Type: application/json' \
   -H 'X-Environment: test' \
   http://apiserver/org/catalog/petstore/getPetDetails?petid=285&storeid=z03

 invoke:
    target-url: https://backend/GetPetInfo/$(request.parameters.storeid)/$(request.parameters.petid)

You can also use an inline reference in the condition property of a switch policy. Consider the following example:

- switch:
    case:
        - condition: "$(request.headers.X-Environment)" == "production"
            execute:
                - invoke:
                    http://www.finance.com/base/stockquote
        - condition: "$(request.headers.X-Environment)" == "test"
            execute:
                - invoke:
                    http://testserver1.finance.com/stockquote

condition: $(request.headers.X-Environment) == "production"

condition: $(request.headers.X-Environment) == "test"

- switch:
    case:
        - condition: request.headers["X-Environment"] == "production"
            execute:
                - invoke:
                    http://www.finance.com/base/stockquote
        - condition: request.headers["X-Environment"] == "test"
            execute:
                - invoke:
                    http://testserver1.finance.com/stockquote

- set-variable:
    actions:
        - set: saved.reqHdrs
           value: $(request.headers)
           type: string

- set-variable:
    actions:
        - set: saved.reqHdrs
           value: $(request.headers)
           type: any

$(request.body.property_name)

$(request.body.account-number)

$(request.body.account.balance)

$(message.body.property_name)