如何使用丰富介体 WSO2 动态添加 json 元素？

Question

I tried using

 <property name="messageType" scope="axis2" type="STRING" value="application/xml"/>
    <property expression="get-property('orderSourceSF')" name="orderSource" scope="default" type="STRING"/>
    <enrich description="">
        <source type="property"  property="orderSource"></source>
        <target action="child" xpath="$body//jsonObject"/>
    </enrich>
    <property name="messageType" scope="axis2" type="STRING" value="application/json"/>
    <payloadFactory media-type="json">
           <format>{request : $1}</format>
           <args>
               <arg evaluator="xml" expression="$body//jsonObject"/>
           </args>
       </payloadFactory>

Here I need to add a element called orderSouce to the existing payload. How can I insert that element. Existing payload is a json request. I am capturing the value of orderSource, but not getting how to insert the element orderSource and the value.

Answer 1

I believe you can use a mediation such as follows to achieve your use case.

    <?xml version="1.0" encoding="UTF-8"?>
<proxy xmlns="http://ws.apache.org/ns/synapse"
       name="enrichProxy"
       startOnLoad="true"
       statistics="disable"
       trace="disable"
       transports="http,https">
   <target>
      <inSequence>
         <property expression="json-eval($)"
                   name="orderSource"
                   scope="default"
                   type="STRING"/>
         <log>
            <property expression="json-eval($)" name="orderSource"/>
         </log>
         <call>
            <endpoint>
               <address uri="http://run.mocky.io/v3/9cf4b844-57c1-4fa5-a101-881dc36385bd"/>
            </endpoint>
         </call>
         <log level="full"/>
         <property name="messageType"
                   scope="axis2"
                   type="STRING"
                   value="application/json"/>
         <enrich>
            <source clone="false" property="orderSource" type="property"/>
            <target action="child" xpath="json-eval($)"/>
         </enrich>
         <payloadFactory media-type="json">
            <format>{"request" : $1}</format>
            <args>
               <arg evaluator="json" expression="$"/>
            </args>
         </payloadFactory>
         <respond/>
      </inSequence>
   </target>
   <description/>
</proxy>
                            

Let me explain what I have done here. Since you are dealing with JSON payloads please use the JSON paths [1] instead of XPATH in your mediation. This will avoid unnecessary data conversion in the mediation.

We are invoking the above proxy service with the following payload.

{"orderSource":"value"}

We are capturing this payload with JSON path and store the value in the property mediator orderSource. Then we are making an endpoint call and it will return the following JSON payload.

{"first":"response"}

As per my understanding, you want to add the value of the property mediator as a child element in the second payload. Thus with the enrich mediator, we can achieve the following payload.

{
        "first": "response",
        "orderSource": "value"
 }

It seems that you want to add this generated payload as a value in another JSON element, so that I have used a payload factory mediator to achieve this use case. Thus this will result in the following payload after the payload factory mediation.

{
    "request": {
        "first": "response",
        "orderSource": "value"
    }
}

[1]-https://docs.wso2.com/display/EI600/JSON+Support

Updated

I have modified the mediation to use the XPTH functions instead of the JSON path. Please refer to the following sample configuration.

<?xml version="1.0" encoding="UTF-8"?>
<proxy xmlns="http://ws.apache.org/ns/synapse"
       name="enrichProxy2"
       startOnLoad="true"
       statistics="disable"
       trace="disable"
       transports="http,https">
   <target>
      <inSequence>
         <property name="messageType"
                   scope="axis2"
                   type="STRING"
                   value="application/xml"/>
         <enrich>
            <source clone="true" xpath="$body//jsonObject/*"/>
            <target property="orderSource" type="property"/>
         </enrich>
         <call>
            <endpoint>
               <address uri="http://run.mocky.io/v3/9cf4b844-57c1-4fa5-a101-881dc36385bd"/>
            </endpoint>
         </call>
         <enrich>
            <source clone="false" property="orderSource" type="property"/>
            <target action="child" xpath="//jsonObject"/>
         </enrich>
         <enrich>
            <source clone="true" xpath="//jsonObject"/>
            <target type="body"/>
         </enrich>
         <respond/>
      </inSequence>
   </target>
   <description/>
</proxy>
           

Update 2

To prevent automatic data conversion you need to configure synapse.commons.json.output.autoPrimitive = false in [ESB_HOME]/repository/conf/synapse.properties file [2].

[2]-https://www.yenlo.com/blog/wso2torial-json-magic-in-wso2-esb-5.0.0