在策略定义中返回响应时如何使用变量? [英] How to use a variable when returning response in policy definition?

问题描述

我正在Azure API管理实例中配置入站策略.

I'm configuring inbound policies in an instance of Azure API Management.

首先，我设置一个变量:

First, I set a variable:

<set-variable name="var1" value="" />

然后我发送一个请求

<send-request mode="new" response-variable-name="var1" timeout="20" ignore-error="false">

哪个返回JSON.测试时，我在跟踪"选项卡中收到以下消息:

Which returns a JSON. When testing I get the following message in trace tab:

获取对"> https://my-api.azure-api.net的请求/api/data "已发送，结果存储在"var1"变量中.

GET request to 'https://my-api.azure-api.net/api/data' has been sent, result stored in 'var1' variable.

我猜发送请求策略有效，结果存储在变量中. 然后我想返回一个响应(仍然在入站，尝试在出站时得到500):

I guess the send-request policy works and the result is stored in the variable. Then I want to return a response (still in inbound, I get 500 when trying to do it in outbound):

<return-response response-variable-name="existing response variable">
    <set-status code="200" reason="OK" />
    <set-header name="Content-Type" exists-action="override">
        <value>application/json</value>
    </set-header>
    <set-body>
    {
        "success": true,
        "var1": context.Variables["var1"]
    }
    </set-body>
</return-response>

我的问题是它不起作用...它只是呈现context.Variables["var1"].

My problem is it doesn't work... It just renders context.Variables["var1"].

也是如此:

• @context.Variables["var1"]
• @{ context.Variables.GetValueOrDefault<string>("var1") }
• @context.Variables.GetValueOrDefault("var1")

• @context.Variables["var1"]
• @{ context.Variables.GetValueOrDefault<string>("var1") }
• @context.Variables.GetValueOrDefault("var1")

所有这些均以书面形式呈现，未提取任何值.

All of them are rendered as written, no value is being extracted.

我还尝试添加一个占位符字符串，然后使用

I also tried adding a placeholder string and then using

<find-and-replace from="Placeholder" to="context.Variables.GetValueOrDefault("var1")" />

并尝试将其放入入站和出站.但是这项政策没有启动.

And try to place it in inbound and outbound alike. But this policy did not launch.

这是我想附加到响应中的JSON对象(小细节:实际上，我有多个变量的问题).

It's a JSON object that I want to append to the response (small detail: in reality I have this issue with multiple variables).

我的问题是:如何将声明的变量添加到响应中?

My question is: how can I add my declared variable to the response?

推荐答案

有两种方法可以解决此问题.您可以为此使用策略表达式: https ://docs.microsoft.com/zh-CN/azure/api-management/api-management-policy-expressions .要记住的是，它们只能用于构建政策的整体价值，而不能构成其一部分，因此:

There are two ways you can go about this. You could to use policy expressions for that: https://docs.microsoft.com/en-us/azure/api-management/api-management-policy-expressions. The thing to remember is that they can only be used to construct whole value for policy, not part of it, so:

<set-body>@("{\"success\": true, \"var1\": " + ((IResponse)context.Variables["var1"]).Body.As<string>() + "}"</set-body>

或者通过set-body策略，您可以使用液体模板:

Or with set-body policy you could use liquid template:

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

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