Calaf Calaf - 2 months ago 26
JSON Question

How can I avoid JSON percent-encoding and \u-escaping?

When I parse the file

<html>
<head><meta charset="UTF-8"></head>
<body><a href="Düsseldorf.html">Düsseldorf</a></body>
</html>


using

item = SimpleItem()
item['name'] = response.xpath('//a/text()')[0].extract()
item["url"] = response.xpath('//a/@href')[0].extract()
return item


I end up with either
\u
escapes

[{
"name": "D\u00fcsseldorf",
"url": "D\u00fcsseldorf.html"
}]


or with percent-encoded strings

D%C3%BCsseldorf


The item exporter described here

# -*- coding: utf-8 -*-
import json
from scrapy.contrib.exporter import BaseItemExporter

class UnicodeJsonLinesItemExporter(BaseItemExporter):

def __init__(self, file, **kwargs):
self._configure(kwargs)
self.file = file
self.encoder = json.JSONEncoder(ensure_ascii=False, **kwargs)

def export_item(self, item):
itemdict = dict(self._get_serialized_fields(item))
self.file.write(self.encoder.encode(itemdict) + '\n')


along with the appropriate feed exporter setting

FEED_EXPORTERS = {
'json': 'myproj.exporter.UnicodeJsonLinesItemExporter',
}


do not help.

How do I get a utf-8-encoded JSON output?

I'm reiterating/expanding an unanswered question.

Update:

Orthogonal to Scrapy, note that without setting

export PYTHONIOENCODING="utf_8"


running

> echo { \"name\": \"Düsseldorf\", \"url\": \"Düsseldorf.html\" } > dorf.json
> python -c'import fileinput, json;print json.dumps(json.loads("".join(fileinput.input())),sort_keys=True, indent=4, ensure_ascii=False)' dorf.json > dorf_pp.json


will fail with

Traceback (most recent call last):
File "<string>", line 1, in <module>
UnicodeEncodeError: 'ascii' codec can't encode character u'\xfc' in position 16: ordinal not in range(128)


Update

As posted my question was unanswerable. The UnicodeJsonLinesItemExporter works, but another part of the pipeline was the culprit: As a post-process to pretty-print the JSON output, I was was using
python -m json.tool in.json > out.json
.

Answer

this seems to work for me

# -*- coding: utf-8 -*-
import scrapy
import urllib

class SimpleItem(scrapy.Item):
    name = scrapy.Field()
    url = scrapy.Field()

class CitiesSpider(scrapy.Spider):
    name = "cities"
    allowed_domains = ["sitercity.info"]
    start_urls = (
        'http://en.sistercity.info/countries/de.html',
    )

    def parse(self, response):
        for a in response.css('a'):
            item = SimpleItem()
            item['name'] = a.css('::text').extract_first()
            item['url'] = urllib.unquote(
                a.css('::attr(href)').extract_first().encode('ascii')
                ).decode('utf8')
            yield item

using the feed exporter cited in your question, it worked also using another storage

# -*- coding: utf-8 -*-
import json
import io
import os
from scrapy.contrib.exporter import BaseItemExporter
from w3lib.url import file_uri_to_path

class CustomFileFeedStorage(object):

    def __init__(self, uri):
        self.path = file_uri_to_path(uri)

    def open(self, spider):
        dirname = os.path.dirname(self.path)
        if dirname and not os.path.exists(dirname):
            os.makedirs(dirname)
        return io.open(self.path, mode='ab')

    def store(self, file):
        file.close()

class UnicodeJsonLinesItemExporter(BaseItemExporter):

    def __init__(self, file, **kwargs):
        self._configure(kwargs)
        self.file = file
        self.encoder = json.JSONEncoder(ensure_ascii=False, **kwargs)

    def export_item(self, item):
        itemdict = dict(self._get_serialized_fields(item))
        self.file.write(self.encoder.encode(itemdict) + '\n')

(removing the comments if necessary)

FEED_EXPORTERS = {
    'json': 'myproj.exporter.UnicodeJsonLinesItemExporter'
}
#FEED_STORAGES = {
#   '': 'myproj.exporter.CustomFileFeedStorage'
#}
FEED_FORMAT = 'json'
FEED_URI = "out.json"