Gzip decompression of http Response

Question

Using request module, I am trying to fetch response from a web service which has following header in the API request:

accept-encoding : gzip

and correspondingly, following header in the response :

content-encoding : gzip

When I am trying to decompress the response(get the correct readable response) using zlib(referred here), I am unable to do so.

Code Snippet :

var options = {
        url: url,
        qs: params.qparams,
        method: params.method,
        json: params.body,
        headers: {
            'api_key': configkey,
            'Content-Type': 'application/json',
            'Accept-Encoding': 'gzip'
        },
        timeout: constants.request_timeout
    };
request(options, function(err, response, body) {

        var encoding = response.headers['content-encoding']
        if (encoding && encoding.indexOf('gzip') >= 0) {
          zlib.gunzip(body, function(err, dezipped) {
            //ERROR : { [Error: incorrect header check] errno: -3, code: 'Z_DATA_ERROR' }
            var json_string = dezipped.toString('utf-8');
            var json = JSON.parse(json_string);
            console.log('\nJSON ::\n',json);
          });
        } else {
            console.log('\n\nRESPONSE IS NOT GZIPPED!');
        }
}

I am getting an error here(as commented in the code), using zlib.

I could not figure out as where is it going wrong, tried with multiple npm modules like unzipResponse and compress-buffer and tried different approaches as well as suggested at various places for handling gzip.

If someone can help out in resolving this, I'll be really thankful.

Mayank Shukla · Accepted Answer · 2019-09-06 14:54:46Z

4

I have got a solution as need to add one more key to the options object as :

var options = {
    url: url,
    qs: params.qparams,
    method: params.method,
    json: params.body,
    headers: {
        'api_key': configkey,
        'Content-Type': 'application/json',
        'Accept-Encoding': 'gzip'
    },
    timeout: constants.request_timeout,
    encoding: null 
};

If someone has a better approach to perform the decompression, please add-on.

edited Sep 6, 2019 at 14:54

Mayank Shukla

105k19 gold badges163 silver badges146 bronze badges

answered Aug 31, 2016 at 11:49

Prerna Jain

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1 Comment

z0d14c Over a year ago

I was using node-wget and getting similar issues for a certain URL. I switched to request and adopted your pattern and then it works. I wish I knew what exactly is going on here.

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