How to merge two variables into one in a response? [duplicate]

Question

I have two APIs added to Azure API Management. It's basically the same API, but for different environments. For monitoring purposes, I want to create an operation that would call the same method in both of the APIs and merge their result into one. I currently work on mocked APIs with mocked data.

To achieve that I created a blank API with a blank operation. Inside this operation, I declared the following inbound policies:

<inbound>
    <set-variable name="env1" value="" />
    <set-variable name="env2" value="" />
    <send-request mode="new" response-variable-name="env1" timeout="20" ignore-error="false">
        <set-url>https://env1-api.azure-api.net/api/data</set-url>
        <set-method>GET</set-method>
        <set-header name="Content-Type" exists-action="override">
            <value>application/json</value>
        </set-header>
    </send-request>
    <send-request mode="new" response-variable-name="env2" timeout="20" ignore-error="false">
        <set-url>https://env2-api.azure-api.net/api/data</set-url>
        <set-method>GET</set-method>
        <set-header name="Content-Type" exists-action="override">
            <value>application/json</value>
        </set-header>
    </send-request>
    <base />
</inbound>

When tested the operation called throws 500 (which, I believe, is understandable, as no response is being set). When I look at the Trace tab I can see two messages:

GET request to 'https://env1-api.azure-api.net/api/data' has been sent, result stored in 'env1' variable.

GET request to 'https://env2-api.azure-api.net/api/data' has been sent, result stored in 'env2' variable.

Based on that I conclude that the calls are working correctly. Here's where I'm stuck. I don't know how to merge those two variables inside a response.

The API's return an array of objects in the form of a JSON object. What I want to achieve is to merge those two responses into one response that will be returned by the operation. How can I compose a response?

Please have in mind that I'm a noob in Azure, so my approach might be too primitive. If you have something better I'd love to hear about it.

Witchcraft

Answer 1

To add to Aleksander's answer, inside the return-response policy, there are two ways you can compose the final body

1. Using policy expressions

<set-body>@{
    var output = new
    {
        success = true,
        var1 = context.Variables["var1"]
    };
    return JsonConvert.SerializeObject(output);
}</set-body>

2. Use liquid templates

<set-variable name="var1body" value="@((IResponse)context.Variables["var1"]).Body.As<string>())" />
<set-body template="liquid">{
"success": true,
"var1": "{{context.Variables["var1body"]}}"
}</set-body>

You can read more about the set-body policy in its doc.

Primero

This answer lacked only parsing of IResponse :-) <set-variable name="var1body" value="@((IResponse)context.Variables["var1"]).Body.As<string>())" /> If you would add it, I would accept it as an answer. – Witchcraft

Added that. Thanks! – Primero

Answer 2

Take a look at return-response policy: https://learn.microsoft.com/en-us/azure/api-management/api-management-advanced-policies#ReturnResponse

Under set-body, you can merge those two strings.

Copilot

While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. – Robbi

Hi, Aleksandar! Although I noticed "return response" before I kind of did not use it, perhaps because the "aborts pipeline execution" sounded kind of like not the thing I wanted to use. I will try that, but still not sure how to compose to the body. – Witchcraft