Spring RestRemplate postforobject with request parameter having integer value

rest, resttemplate, spring, spring-mvc

Solution

The root cause of this error is that by specifying an `Integer` in the `LinkedMultiValueMap`, the `RestTemplate` will take that to mean that your request is a multipart request. There is no `HttpMessageConverter` registered by default that can handle writing values of type `Integer` to a request body.

As you said, you can handle this situation by changing the `count` to be a `String`. After all, there is no `Integer` type in HTTP request parameters. However, you were worried

But I might need to pass complex data types as parameters later.

Assume something like this

public @ResponseBody MyResponse processRequest(String RequestId, int count, Complex complex) {

with

public class Complex {
    private String someValue;
    private int intValue;

    public String getSomeValue() {
        return someValue;
    }

    public void setSomeValue(String someValue) {
        this.someValue = someValue;
    }

    public int getIntValue() {
        return intValue;
    }

    public void setIntValue(int intValue) {
        this.intValue = intValue;
    }

    public String toString() {
        return someValue + " " + intValue;
    }
}

The the following will work just fine

MultiValueMap<String, Object> map = new LinkedMultiValueMap<String, Object>();
map.add("RequestId", "asd");
map.add("count", "42");
map.add("someValue", "complex");
map.add("intValue", "69");
restTemplate.postForObject(url, map,MyResponse.class);

Remember that the request parameters are used to populate the fields of model attributes by their names.

An even better solution would have you using a serialization standard like JSON or XML.

Problem

I have a method in Spring rest service. ``` @RequestMapping(value = "test/process", method = RequestMethod.POST) public @ResponseBody MyResponse processRequest(String RequestId, int count) ``` I am using Spring RestTemplate to call this service like this. ``` RestTemplate restTemplate = this.getRestTemplate(); MultiValueMap<String, Object> map = new LinkedMultiValueMap<String, Object>(); map.add("RequestId", RequestId); map.add("count", count); restTemplate.postForObject(url, map,MyResponse.class); ``` When I try to invoke the client method I get the exception that no suitable HttpMessageConverter found for request type [java.lang.Integer] ``` org.springframework.http.converter.HttpMessageNotWritableException: Could not write request: no suitable HttpMessageConverter found for request type [java.lang.Integer] at org.springframework.http.converter.FormHttpMessageConverter.writePart(FormHttpMessageConverter.java:310) at org.springframework.http.converter.FormHttpMessageConverter.writeParts(FormHttpMessageConverter.java:270) at org.springframework.http.converter.FormHttpMessageConverter.writeMultipart(FormHttpMessageConverter.java:260) at org.springframework.http.converter.FormHttpMessageConverter.write(FormHttpMessageConverter.java:200) at org.springframework.http.converter.FormHttpMessageConverter.write(FormHttpMessageConverter.java:1) at org.springframework.web.client.RestTemplate$HttpEntityRequestCallback.doWithRequest(RestTemplate.java:596) at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:444) at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:409) at org.springframework.web.client.RestTemplate.postForObject(RestTemplate.java:287) ``` I know one of the ways is to pass all the parameters as String. But I might need to pass complex data types as parameters later. What is the ways to achieve this. I have googled and some option seem to be writing my own converters. How should I start about solving this problem.

Original source