我花了整整一天的时间试图弄清楚如何实现这一点。最终，我遇到了一个从2016年开始就从未合并过的Scrapy拉取请求，并实现了一个多部分表单请求：
from scrapy import FormRequestfrom six.moves.urllib.parse import urljoin, urlenpreimport lxml.htmlfrom parsel.selector import create_root_nodeimport siximport stringimport randomfrom scrapy.http.request import Requestfrom scrapy.utils.python import to_bytes, is_listlikefrom scrapy.utils.response import get_base_urlclass MultipartFormRequest(FormRequest): def __init__(self, *args, **kwargs): formdata = kwargs.pop('formdata', None) kwargs.setdefault('method', 'POST') super(MultipartFormRequest, self).__init__(*args, **kwargs) content_type = self.headers.setdefault(b'Content-Type', [b'multipart/form-data'])[0] method = kwargs.get('method').upper() if formdata and method == 'POST' and content_type == b'multipart/form-data': items = formdata.items() if isinstance(formdata, dict) else formdata self._boundary = '' # enpre the data using multipart spec self._boundary = to_bytes(''.join( random.choice(string.digits + string.ascii_letters) for i in range(20)), self.encoding) self.headers[b'Content-Type'] = b'multipart/form-data; boundary=' + self._boundary request_data = _multpart_enpre(items, self._boundary, self.encoding) self._set_body(request_data)class MultipartFile(object): def __init__(self, name, content, mimetype='application/octet-stream'): self.name = name self.content = content self.mimetype = mimetypedef _get_form_url(form, url): if url is None: return urljoin(form.base_url, form.action) return urljoin(form.base_url, url)def _urlenpre(seq, enc): values = [(to_bytes(k, enc), to_bytes(v, enc)) for k, vs in seq for v in (vs if is_listlike(vs) else [vs])] return urlenpre(values, doseq=1)def _multpart_enpre(items, boundary, enc): body = [] for name, value in items: body.append(b'--' + boundary) if isinstance(value, MultipartFile): file_name = value.name content = value.content content_type = value.mimetype body.append( b'Content-Disposition: form-data; name="' + to_bytes(name, enc) + b'"; filename="' + to_bytes(file_name,enc) + b'"') body.append(b'Content-Type: ' + to_bytes(content_type, enc)) body.append(b'') body.append(to_bytes(content, enc)) else: body.append(b'Content-Disposition: form-data; name="' + to_bytes(name, enc) + b'"') body.append(b'') body.append(to_bytes(value, enc)) body.append(b'--' + boundary + b'--') return b'rn'.join(body)def _get_form(response, formname, formid, formnumber, formxpath): """Find the form element """ root = create_root_node(response.text, lxml.html.HTMLParser, base_url=get_base_url(response)) forms = root.xpath('//form') if not forms: raise ValueError("No <form> element found in %s" % response) if formname is not None: f = root.xpath('//form[@name="%s"]' % formname) if f: return f[0] if formid is not None: f = root.xpath('//form[@id="%s"]' % formid) if f: return f[0] # Get form element from xpath, if not found, go up if formxpath is not None: nodes = root.xpath(formxpath) if nodes: el = nodes[0] while True: if el.tag == 'form': return el el = el.getparent() if el is None: break enpred = formxpath if six.PY3 else formxpath.enpre('unipre_escape') raise ValueError('No <form> element found with %s' % enpred) # If we get here, it means that either formname was None # or invalid if formnumber is not None: try: form = forms[formnumber] except IndexError: raise IndexError("Form number %d not found in %s" % (formnumber, response)) else: return formdef _get_inputs(form, formdata, dont_click, clickdata, response): try: formdata = dict(formdata or ()) except (ValueError, TypeError): raise ValueError('formdata should be a dict or iterable of tuples') inputs = form.xpath('descendant::textarea' '|descendant::select' '|descendant::input[not(@type) or @type[' ' not(re:test(., "^(?:submit|image|reset)$", "i"))' ' and (../@checked or' ' not(re:test(., "^(?:checkbox|radio)$", "i")))]]', namespaces={ "re": "http://exslt.org/regular-expressions"}) values = [(k, u'' if v is None else v) for k, v in (_value(e) for e in inputs) if k and k not in formdata] if not dont_click: clickable = _get_clickable(clickdata, form) if clickable and clickable[0] not in formdata and not clickable[0] is None: values.append(clickable) values.extend(formdata.items()) return valuesdef _value(ele): n = ele.name v = ele.value if ele.tag == 'select': return _select_value(ele, n, v) return n, vdef _select_value(ele, n, v): multiple = ele.multiple if v is None and not multiple: # Match browser behaviour on simple select tag without options selected # And for select tags wihout options o = ele.value_options return (n, o[0]) if o else (None, None) elif v is not None and multiple: # This is a workround to bug in lxml fixed 2.3.1 # fix https://github.com/lxml/lxml/commit/57f49eed82068a20da3db8f1b18ae00c1bab8b12#L1L1139 selected_options = ele.xpath('.//option[@selected]') v = [(o.get('value') or o.text or u'').strip() for o in selected_options] return n, vdef _get_clickable(clickdata, form): """ Returns the clickable element specified in clickdata, if the latter is given. If not, it returns the first clickable element found """ clickables = [ el for el in form.xpath( 'descendant::*[(self::input or self::button)' ' and re:test(@type, "^submit$", "i")]' '|descendant::button[not(@type)]', namespaces={"re": "http://exslt.org/regular-expressions"}) ] if not clickables: return # If we don't have clickdata, we just use the first clickable element if clickdata is None: el = clickables[0] return (el.get('name'), el.get('value') or '') # If clickdata is given, we compare it to the clickable elements to find a # match. We first look to see if the number is specified in clickdata, # because that uniquely identifies the element nr = clickdata.get('nr', None) if nr is not None: try: el = list(form.inputs)[nr] except IndexError: pass else: return (el.get('name'), el.get('value') or '') # We didn't find it, so now we build an XPath expression out of the other # arguments, because they can be used as such xpath = u'.//*' + u''.join(u'[@%s="%s"]' % c for c in six.iteritems(clickdata)) el = form.xpath(xpath) if len(el) == 1: return (el[0].get('name'), el[0].get('value') or '') elif len(el) > 1: raise ValueError("Multiple elements found (%r) matching the criteria " "in clickdata: %r" % (el, clickdata)) else: raise ValueError('No clickable element matching clickdata: %r' % (clickdata,))这是我用来调用请求的代码（在我的情况下，我需要上传图片）：
with open(img_path, 'rb') as file: img = file.read() file_name = os.path.basename(img_path) multipart_file = MultipartFile(file_name, img, "image/png") form_data = { "param": "value", # this is an example of a text parameter "PicUpload": multipart_file } yield MultipartFormRequest(url=upload_url, formdata=form_data, callback=self.my_callback)可惜的是，已经过去了这么长时间，而Scrapy仍然没有内置的方法来执行此操作，特别是因为几年前有人编写了一个非常简单的实现。
