Feature: Support for JsonPath in the response (with HandleBars)

[zubinix]

Does WireMock.Net have support for the jsonPath helper found in the java based WireMock? I want to create a template that inserts in the response items from a JSON request. It seems all I can do with WireMock-Net 'out of the box' is use {{request.body}} in the response template which returns the entire JSON body of the request?

[StefH]

Currently it's only supported that you can use a jsonmatcher on the request. See https://github.com/WireMock-Net/WireMock.Net/wiki/Stubbing-and-Request-Matching#json-jsonmatcher

It's not yet supported that you can use JsonPath in the output, like you can do with handlebars : https://github.com/WireMock-Net/WireMock.Net/wiki/Stubbing-and-Request-Matching#response-templating

[zubinix]

Is there a plan to do so? Is there a HandleBar feature I can use instead to extract parts from the request body?

[StefH]

There is no HandleBars functionality out of the box. I can extend the code to support something like this:

// select single token
"{{JSONPath.SelectToken response.body \"$.Manufacturers[?(@.Name == 'Acme Co')]\"}}"

Where response.body is the response body in json.
And the $.Manufacturers[?(@.Name == 'Acme Co')] is the JSONPath expression (copied from example here: https://www.newtonsoft.com/json/help/html/QueryJsonSelectTokenJsonPath.htm)

Also selecting multiple tokens should be possible:

// select multiple tokens
"{{#JSONPath.SelectTokens response.body \"$..Products[?(@.Price >= 50)].Name\"}}{{token}}{{/JSONPath.SelectTokens}}"

[zubinix]

That sounds great. When do you think you can add this feature?

[StefH]

Currently I am fixing this issue #148 (comment).

After that I will continue on this one.

If the proposed fix here is enough for you and will comply to all your requirements, I will implement it as is.

[StefH]

Preview NuGet can be found at
https://www.nuget.org/packages/WireMock.Net/1.0.4.7-preview-jsonpath

Note that the syntax has been changed from JSONPath.SelectToken to JsonPath.SelectToken !

[zubinix]

Thanks StefH. I will take a look and get back to you.

[zubinix]

My request input I'm trying to match is

{"username": "Zubin"}

using

    "Response": {
      "UseTransformer": true,
      "StatusCode": 200,
      "BodyAsJson": { "result": "{{JsonPath.SelectToken response.body \"@.username\"}}" },
      "Headers": {
        "Content-Type": "application/json"
      }
    }

but I get

{
    "Status": "{\"ClassName\":\"System.NotSupportedException\",\"Message\":\"The value '' with type HandlebarsDotNet.Compiler.UndefinedBindingResult cannot be used in Handlebars JsonPath.\",\"Data\":null,\"InnerException\":null,\"HelpURL\":null,\"StackTraceString\":\"   at WireMock.Transformers.HandlebarsHelpers.Parse(Object[] arguments)\\r\\n   at WireMock.Transformers.HandlebarsHelpers.<>c.<Register>b__0_0(TextWriter writer, Object context, Object[] arguments)\\r\\n   at lambda_method(Closure , TextWriter , Object )\\r\\n   at HandlebarsDotNet.Handlebars.HandlebarsEnvironment.<>c__DisplayClass7_0.<Compile>b__0(Object context)\\r\\n   at WireMock.Transformers.ResponseMessageTransformer.Transform(RequestMessage requestMessage, ResponseMessage original)\\r\\n   at WireMock.ResponseBuilders.Response.ProvideResponseAsync(RequestMessage requestMessage)\\r\\n   at WireMock.Mapping.ResponseToAsync(RequestMessage requestMessage)\\r\\n   at WireMock.Owin.WireMockMiddleware.Invoke(HttpContext ctx)\",\"RemoteStackTraceString\":null,\"RemoteStackIndex\":0,\"ExceptionMethod\":null,\"HResult\":-2146233067,\"Source\":\"WireMock.Net\",\"WatsonBuckets\":null}"
}

What am I doing wrong?

[StefH]

1] You want to use the request I guess
2] Also try request.bodyAsJson instead of request.body?

So: {{JsonPath.SelectToken request.bodyAsJson \"@.username\"}}

See also this code : https://github.com/WireMock-Net/WireMock.Net/blob/SupportJSONPath_in_the_response/test/WireMock.Net.Tests/ResponseBuilderTests/ResponseWithHandlebarsTests.cs#L384

[zubinix]

Yep should have used request.body but still getting

{
    "Status": "{\"ClassName\":\"System.NotSupportedException\",\"Message\":\"The value '' with type HandlebarsDotNet.Compiler.UndefinedBindingResult cannot be used in Handlebars JsonPath.\",\"Data\":null,\"InnerException\":null,\"HelpURL\":null,\"StackTraceString\":\"   at WireMock.Transformers.HandlebarsHelpers.Parse(Object[] arguments)\\r\\n   at WireMock.Transformers.HandlebarsHelpers.<>c.<Register>b__0_0(TextWriter writer, Object context, Object[] arguments)\\r\\n   at lambda_method(Closure , TextWriter , Object )\\r\\n   at HandlebarsDotNet.Handlebars.HandlebarsEnvironment.<>c__DisplayClass7_0.<Compile>b__0(Object context)\\r\\n   at WireMock.Transformers.ResponseMessageTransformer.Transform(RequestMessage requestMessage, ResponseMessage original)\\r\\n   at WireMock.ResponseBuilders.Response.ProvideResponseAsync(RequestMessage requestMessage)\\r\\n   at WireMock.Mapping.ResponseToAsync(RequestMessage requestMessage)\\r\\n   at WireMock.Owin.WireMockMiddleware.Invoke(HttpContext ctx)\",\"RemoteStackTraceString\":null,\"RemoteStackIndex\":0,\"ExceptionMethod\":null,\"HResult\":-2146233067,\"Source\":\"WireMock.Net\",\"WatsonBuckets\":null}"
}

The input request I'm trying to grab data from is very simple just:

{"username": "Zubin"}

I'm just trying to make "Zubin" appear the response.

[StefH]

You should use username instead of @.username.
And the BodyAsJson does not (yet) work, so you need to use this solution:

{
    "Guid": "407e031f-c96b-429d-8a58-01c6a456fedd",
    "Priority": 0,
    "Request": {
        "Path": {
            "Matchers": [
                {
                    "Name": "WildcardMatcher",
                    "Pattern": "/zubinix",
                    "IgnoreCase": false
                }
            ]
        },
        "Methods": [
            "post"
        ]
    },
    "Response": {
        "StatusCode": 200,
        "BodyDestination": "SameAsSource",
        "Body": "{ \"result\": \"{{JsonPath.SelectToken request.body \"username\"}}\" }",
        "UseTransformer": true,
        "Headers": {
            "Content-Type": "application/json"
        }
    }
}

Note that you also can use request.bodyAsJson.

[zubinix]

That did the trick. Thanks.

[StefH]

I did update the code, so now also BodyAsJson (in the response) is supported, see this mapping:

{
  "Request": {
    "Path": {
      "Matchers": [
        {
          "Name": "WildcardMatcher",
          "Pattern": "/zubinix2",
          "IgnoreCase": false
        }
      ]
    },
    "Methods": [
      "post"
    ],
    "Body": {}
  },
  "Response": {
    "StatusCode": 200,
    "BodyAsJson": {
      "path": "{{request.path}}",
      "result": "{{JsonPath.SelectToken request.bodyAsJson \"username\"}}"
    },
    "UseTransformer": true,
    "Headers": {
      "Content-Type": "application/json"
    }
  }
}

New Nuget (1.0.4.8-preview-01) is available.

Please test

[zubinix]

Trying the above. What could be causing this error?

{
    "Status": "{\"ClassName\":\"System.ArgumentNullException\",\"Message\":\"Value cannot be null.\",\"Data\":null,\"InnerException\":null,\"HelpURL\":null,\"StackTraceString\":\"   at WireMock.Validation.Check.NotNull[T](T value, String parameterName)\\r\\n   at WireMock.Transformers.HandlebarsHelpers.Parse(Object[] arguments)\\r\\n   at WireMock.Transformers.HandlebarsHelpers.<>c.<Register>b__0_0(TextWriter writer, Object context, Object[] arguments)\\r\\n   at HandlebarsDotNet.Handlebars.HandlebarsEnvironment.<>c__DisplayClass7_0.<Compile>b__0(Object context)\\r\\n   at WireMock.Transformers.ResponseMessageTransformer.WalkNode(JToken node, Object template)\\r\\n   at WireMock.Transformers.ResponseMessageTransformer.WalkNode(JToken node, Object template)\\r\\n   at WireMock.Transformers.ResponseMessageTransformer.TransformBodyAsJson(Object template, ResponseMessage original, ResponseMessage responseMessage)\\r\\n   at WireMock.Transformers.ResponseMessageTransformer.Transform(RequestMessage requestMessage, ResponseMessage original)\\r\\n   at WireMock.ResponseBuilders.Response.ProvideResponseAsync(RequestMessage requestMessage)\\r\\n   at WireMock.Mapping.ResponseToAsync(RequestMessage requestMessage)\\r\\n   at WireMock.Owin.WireMockMiddleware.Invoke(HttpContext ctx)\",\"RemoteStackTraceString\":null,\"RemoteStackIndex\":0,\"ExceptionMethod\":null,\"HResult\":-2147467261,\"Source\":\"WireMock.Net\",\"WatsonBuckets\":null,\"ParamName\":\"arguments[0]\"}"
}

For input

    "Response": {
      "UseTransformer": true,
      "StatusCode": 200,
      "BodyAsJson": {
      	"path": "{{request.path}}",
        "result": "{{JsonPath.SelectToken request.bodyAsJson \"username\"}}" 
      },
      "Headers": {
        "Content-Type": "application/json"
      }
    }

[StefH]

When you send a request, do you also provide the Content-Type header with value application/json?

Like:

[zubinix]

Oh yes, I was missing the header in the request. Works now but interesting if I delete the header it still works! So the header is required the first time only? I'm using fiddler and postman as follows:

1. Add mapping (using postman).
2. Send request without application/json header using postman -> error above received. Verified in fiddler.
3. Edit request in fiddler and add application/json header -> correct response received.
4. Send the original request without the header from postman -> correct response received without using header??? caching???

[StefH]

Very strange. There is no caching on the request, that would break the whole WireMock functionality. For now, do you think it works as excepted ? If so, this issue can be closed, and then I'll create a new official NuGet.

[zubinix]

Yes. Please close and create the NuGet. Thanks! I might create another issue relating to this apparent caching after get some more experience this tool.

[zubinix]

Support for Json request parameters in response has been added.