Need to modify response using Azure APIM set-body policy - azure

Question

I am relatively new to Azure APIM and I have this backend which I am able to invoke which returns the response in format
{
"data": {
"attributes": {
"municipalities": []
}
}
}
I want to modify the response so that the data is returned in the format
{
"data": {
"municipalities": []
}
}
I have tried using the set body liquid template
<outbound>
<set-body template="liquid">
{
"data": {
"municipalities": {{body.data.attributes.municipalities}}
}
}</set-body>
</outbound>
But the response I get is just
{
"data": {
"municipalities":
}
}
If someone can point out to me what I am doing wrong or if there is a better way to do this?
I also tried to use the below code just to check if I am able to retrieve the "data" attribute but I got the below error in the trace part of Azure APIM Test
<outbound>
<set-body>
#{
JObject inBody = context.Request.Body.As<JObject>();
return inBody["data"].ToString();
}
</set-body>
</outbound>
ERROR:
{
"messages": [
{
"message": "Expression evaluation failed.",
"expression": " \n JObject inBody = context.Request.Body.As<JObject>();\n return inBody[\"data\"].ToString(); \n",
"details": "Object reference not set to an instance of an object."
},
"Expression evaluation failed. Object reference not set to an instance of an object.",
"Object reference not set to an instance of an object."
]
}

Answer 1

As body.data.attributes.municipalities is a array, we can't put it "municipalities": directly. For your requirement of modify the format of the json data, we need to write every property of each array item. Below is my steps for your reference.
My json is:
{
"data": {
"attributes": {
"municipalities": [
{
"name": "hury",
"email": "hury#mail.com"
},
{
"name": "mike",
"email": "mike#email.com"
}
]
}
}
}
And my liquid template show as:
==============================Update============================
First the code JObject inBody = context.Request.Body.As<JObject>(); you shared can't get the response data. You should use JObject inBody = context.Response.Body.As<JObject>();.
Then for your question about "Is there an easier way to remove .attributes part, I provide a solution below for your reference.
Do not use liquid template, use Replace to replace "attributes": { with empty and use Substring to remove the last }.
<set-body>#{
JObject inBody = context.Response.Body.As<JObject>();
string str = inBody.ToString();
string str1 = str.Replace("\"attributes\": {", "");
string result = str1.Substring(0, str1.Length-1);
return result;
}</set-body>
Notice: This approach requires a high degree of specification for your response data format.

Answer 2

I also managed to get the desired output with the below code, so that the code is generic and doesnt need to do any string operations.
<set-body>#{
JToken inBody = context.Response.Body.As<JToken>()["data"]["attributes"];
JObject jsonObject = new JObject{
["data"] = inBody
};
return jsonObject.ToString();
}</set-body>