[jira] [Created] (NUTCH-2471) Returning a bare string meant to be application/json doesn't properly quote the string

[Ninaad Joshi (JIRA)]

Ninaad Joshi created NUTCH-2471:
-----------------------------------

             Summary: Returning a bare string meant to be application/json 
doesn't properly quote the string
                 Key: NUTCH-2471
                 URL: https://issues.apache.org/jira/browse/NUTCH-2471
             Project: Nutch
          Issue Type: Bug
          Components: nutch server
    Affects Versions: 2.3.1
            Reporter: Ninaad Joshi
            Priority: Blocker


Nutch Server resources are JAX-RS resources and that they proclaims to produce 
JSON even for a resource method that returns a String...... 

{code:java}
@Produces({ MediaType.APPLICATION_JSON })
public abstract class AbstractResource {
.....
}

@Path("/config")
public class ConfigResource extends AbstractResource {
...
@GET
  @Path("/{configId}/{propertyId}")
  public String getProperty(@PathParam("configId") String configId,
      @PathParam("propertyId") String propertyId) {
    return configManager.getAsMap(configId).get(propertyId);
  }
}
{code}

the HTTP response indicates it is an application/json response, however the 
string returned is not properly quoted for JSON. We also get de-serialization 
errors on the client side.

{noformat}
server: Restlet-Framework/2.2.3
date: Wed, 06 Dec 2017 10:30:13 GMT
content-type: application/json; charset=UTF-8
content-length: 21
accept-ranges: bytes

There was an error parsing JSON data
Unexpected token B in JSON at position 0
{noformat}

The JAX-RS resources are configured to use JacksonJsonProvider for writing the 
JSON message body. JacksonJsonProvider.isWriteable() is indicating that it 
cannot write the value because _untouchables includes String.class. It appears 
String.class was put back into the _untouchables list as a result of this [link 
bug|https://github.com/FasterXML/jackson-jaxrs-json-provider/issues/12]
That bug, however, appears to have been targeted at dealing with an XML issue, 
not a JSON issue. 

It should have been ideally taken care by the Jackson providers. However, it's 
not and hence proposing this fix.
* Create our own custom NutchJsonProvider based on JacksonJsonProvider and 
remove the String.class from the _untouchables
* Register this NutchJsonProvider with NutchServer to be used while writing 
JSON message body 

I have attached the patch along with this issue

The other option is to JsonEscape the string and pad it with double quotes 
before returning. This has to be done at all places wherever string is returned 
as Json response and also is prone to errors in future if anybody misses this 
escaping and padding.




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