How to access another conditional flow in the same endpoint? - node.js

Question

Background
We have an api proxy with two conditional flows:
GetAllProducts
GetSingleProduct
GetAllProducts gets all product from our backend server. Requests to GetAllProducts are cached for some time.
GetSingleProduct does not access our backend server. It will just access GetAllProducts to get all products and then find the single product and return it. It performs the request in node.
Issue
GetSingleProduct must know the url for the api proxy, and we don't want to hardcode the url. I have tried the following policy to add a query string parameter that is passed to the node server:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<AssignMessage async="false" continueOnError="false" enabled="true" name="assign-message-path">
<DisplayName>Assign Message Path</DisplayName>
<FaultRules/>
<Properties/>
<Add>
<Headers/>
<QueryParams>
<QueryParam name="apiProxyUri">{client.scheme}://{client.host}:{client.port}{message.uri}</QueryParam>
</QueryParams>
</Add>
<IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
<AssignTo createNew="false" transport="http" type="request"/>
</AssignMessage>
The issue is that client.host and client.port are 'wrong'. They are set to some other ip and port that I don't really know what mean. Perhaps they are apigee-internal. However, what matters is that it doesn't work, but if I modify the line to hard-coded host and port it works:
<QueryParam name="apiProxyUri">{client.scheme}://90.123.123.123:9001{message.uri}</QueryParam>
Other things I've tried
I have read the variable reference page to find other variables that potentially could be used, with no luck. I've also considered using the variable virtualhost.name but there is no variable called virtualhost.port that would be needed as well.
Update with remaining issues
I've modified the proxy according to the answers below from Srikanth and Mike Dunker. I've chosen to do it like Srikanth suggests (two separate proxy flows for GetAllProducts and GetSingleProduct). See current flow for GetSingleProduct here.
Extract Product policy xml:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ExtractVariables async="false" continueOnError="false" enabled="true" name="extract-product">
<DisplayName>Extract Product</DisplayName>
<FaultRules/>
<Properties/>
<IgnoreUnresolvedVariables>false</IgnoreUnresolvedVariables>
<JSONPayload>
<Variable name="product">
<JSONPath>$.[?(#.id == {main.id})]</JSONPath>
</Variable>
</JSONPayload>
<Source clearPayload="false">response</Source>
<VariablePrefix>main</VariablePrefix>
</ExtractVariables>
Remaining issues:
When the jsonpath matches a specific product, the result is an array with a single item. How can I get the item itself, instead of an array with a single item?
When the jsonpath does not match any product, the result is an empty array. In this case the step 'Fault Invalid Id' should execute. How should I define the condition for that step?

Answer 1

If you situation is same as "Call Another API Proxy from one API Proxy in the same organization" then its not recommended.
if the flows are in the same proxy, the you can put GetAllProducts in target flow and GetSingleProduct passes the request to the target flow containing GetAllProducts.
In summary,
For GetAllProducts
Proxy flow - none, Target flow - GetAllProducts
For GetSingleProduct
Proxy flow - GetSingleProduct, Target flow - GetAllProducts (same target end point as above)

Answer 2

Your solution can be simpler (and perform better) than calling back into the proxy.
1) Create a single proxy flow with a condition that matches both GetSingleProduct and GetAllProducts.
2) Proxy flow request #1: set a variable that specifies whether GetAllProducts or GetSingleProduct was called (or just save the pathsuffix). This way when you rewrite GetSingleProduct to look like GetAllProducts for your backend, you will be able to handle the GetSingleProduct steps later in the response.
3) Proxy flow request #2: handle the backend request just like you would for GetAllProducts in your current design: checking the response cache, building the GetAllProducts request, sending it.
4) Proxy flow response #1: handle the backend response just like you would for GetAllProducts in your current design: get the response, populate the response cache.
5) Proxy flow response #2: in the next steps, if the original request was GetSingleProduct, extract the single product from the response (after the cache check). You just need to have the GetSingleProduct condition for all the GetSingleProduct steps.
That should get you what you need without calling out again.
Answers to remaining issues
I don't think you can use "main.product.length == 0" in your "Fault Invalid Id" condition, but you could try it. Regardless, you'll need to do something to grab the single item (remaining issue #1).
I would probably create a JavaScript policy that follows your extract variables policy. It could check the length of the main.product array, and set a flag if the length is 0 (which could then be used for your fault rule condition). If the length is 1, you could grab the single matching product.