Deserialize DD4T content error while validating DXA Model service

Question

I am following the below url to configure DD4T 2.0 to consume DXA Model Service: http://blog.trivident.com/switching-to-the-dxa-2-model-service-in-your-dd4t-application/

As per above article, when we try to validate the Model Service to read content published from DD4T 2.0 templates using Postman, we are getting the below error:

{
    "timestamp": [
        "String",
        "2018-06-01T07:50:12.821+0000"
    ],
    "status": 500,
    "error": "Internal Server Error",
    "exception": "com.sdl.webapp.common.api.content.ContentProviderException",
    "message": "Couldn't deserialize DD4T content for request PageRequestDto(publicationId=32, uriType=tcm, path=/somepage/index.htm, includePages=INCLUDE, contentType=MODEL, dataModelType=R2, expansionDepth=100, depthCounter=com.sdl.dxa.common.dto.DepthCounter@9f)",
    "path": "/PageModel/tcm/32/somepage/index.htm"
}

The content is coming fine when we are using the content service URL in compressed JSON format

Updated v2: Updated the logback of model service - debug mode.

The logs genrated in dxa.date.log shows below error:

DEBUG c.s.d.m.s.ContentService - Trying to request a page with localization id = '32' and path = '/somepage/index.htm' 

DEBUG c.s.d.m.s.ContentService - Requested publication '32', path '/somepage/index.htm', result is '[tcm:xx-xxxxxx-xx]'

INFO  c.s.d.m.s.DefaultPageModelService - Found DD4T model while requested R2, need to convert, no expansion needed, request PageRequestDto(publicationId=32, uriType=tcm, path=/somepage/index.htm, includePages=INCLUDE, contentType=MODEL, dataModelType=R2, expansionDepth=100, depthCounter=com.sdl.dxa.common.dto.DepthCounter@9f) 

ERROR o.d.d.b.j.JsonDataBinder - Error deserializing. 
com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'H4sIAAAAAAAEAO1d647bOJZ': was expecting ('true', 'false' or 'null')
 at [Source: (String)"H4sIAAAAAAAEAO1d647bOJZ+Fa5.......tNXVVEErz59eAs+"[truncated 10300 chars]; line: 1, column: 24]
    at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1804)
    ......

Can you please help in resolving the above error.

Answer 1

It's related to DD4T compressed JSON.

To fix this issue disable the compress JSON output on the DD4T templates on both CT and PT and republish the pages and DCPs.

Model Service supports DXA R2 format and DD4T format, maybe not compressed output.

DXA 2 data format is more compact and will probably make publishing a bit faster. you might consider to replace the DD4T template building blocks with the new DXA R2 TBBs and republish all your pages.

I hope it helps.