Scrapy crawling not working on ASPX website

If you look at the data posted to the form in chrome or firebug you can see there are many fields passed in the post request, there are a few that are essential and must be parsed from the original page, parsing the ids from the div.sangria ul li a tags is not sufficient as the actual data posted is slightly different, what is posted is in the Javascript function, WebForm_DoPostBackWithOptions which is in the href not the id attribute:

href='javascript:WebForm_DoPostBackWithOptions(new 
 WebForm_PostBackOptions("ctl00$m$g_36ea0310_893d_4a19_9ed1_88a133d06423$ctl00$Repeater1$ctl03$lnk_Grupo", "", true, "", "", false, true))'>

Sometimes all the underscores are replaced with dollar signs so it is easy to do a str.replace to get them in the correct order but not really in this case, we could use a regex to parse but I like the js2xml lib which can parse a javascript function and its args into an xml tree.

The following code using requests shows you how can get the data from the initial request and get to all the pages you want:

import requests
from  lxml import html
import js2xml

post = "http://www.asambleamadrid.es/ES/QueEsLaAsamblea/ComposiciondelaAsamblea/LosDiputados/Paginas/RelacionAlfabeticaDiputados.aspx"


def validate(xml):
    # these fields are the minimum required as cannot be hardcoded
    data = {"__VIEWSTATEGENERATOR": xml.xpath("//*[@id='__VIEWSTATEGENERATOR']/@value")[0],
            "__EVENTVALIDATION": xml.xpath("//*[@id='__EVENTVALIDATION']/@value")[0],
            "__VIEWSTATE": xml.xpath("//*[@id='__VIEWSTATE']/@value")[0],
            " __REQUESTDIGEST": xml.xpath("//*[@id='__REQUESTDIGEST']/@value")[0]}
    return data



with requests.Session() as s:
    # make initial requests to get the links/hrefs and the from fields
    r = s.get(
        "http://www.asambleamadrid.es/ES/QueEsLaAsamblea/ComposiciondelaAsamblea/LosDiputados/Paginas/RelacionAlfabeticaDiputados.aspx")
    xml = html.fromstring(r.content)
    hrefs = xml.xpath("//*[@id='moduloBusqueda']//div[@class='sangria']/ul/li/a/@href")
    form_data = validate(xml)
    for h in hrefs:
        js_xml = js2xml.parse(h)
        _id = js_xml.xpath(
            "//identifier[@name='WebForm_PostBackOptions']/following-sibling::arguments/string[starts-with(.,'ctl')]")[
            0]
        form_data["__EVENTTARGET"] = _id.text
        r = s.post(post, data=form_data)
        xml = html.fromstring(r.content)
        print(xml.xpath("//ul[@class='listadoVert02']/ul/li/a/text()"))

If we run the code above we see the different text output from all teh anchor tags:

In [2]: with requests.Session() as s:
   ...:         r = s.get(
   ...:             "http://www.asambleamadrid.es/ES/QueEsLaAsamblea/ComposiciondelaAsamblea/LosDiputados/Paginas/RelacionAlfabeticaDiputados.aspx")
   ...:         xml = html.fromstring(r.content)
   ...:         hrefs = xml.xpath("//*[@id='moduloBusqueda']//div[@class='sangria']/ul/li/a/@href")
   ...:         form_data = validate(xml)
   ...:         for h in hrefs:
   ...:                 js_xml = js2xml.parse(h)
   ...:                 _id = js_xml.xpath(
   ...:                     "//identifier[@name='WebForm_PostBackOptions']/following-sibling::arguments/string[starts-with(.,'ctl')]")[
   ...:                     0]
   ...:                 form_data["__EVENTTARGET"] = _id.text
   ...:                 r = s.post(post, data=form_data)
   ...:                 xml = html.fromstring(r.content)
   ...:                 print(xml.xpath("//ul[@class='listadoVert02']/ul/li/a/text()"))
   ...:         
[u'Abo\xedn Abo\xedn, Sonsoles Trinidad', u'Adrados Gautier, M\xaa Paloma', u'Aguado Del Olmo, M\xaa Josefa', u'\xc1lvarez Padilla, M\xaa Nadia', u'Arribas Del Barrio, Jos\xe9 M\xaa', u'Ballar\xedn Valc\xe1rcel, \xc1lvaro C\xe9sar', u'Berrio Fern\xe1ndez-Caballero, M\xaa In\xe9s', u'Berzal Andrade, Jos\xe9 Manuel', u'Cam\xedns Mart\xednez, Ana', u'Carballedo Berlanga, M\xaa Eugenia', 'Cifuentes Cuencas, Cristina', u'D\xedaz Ayuso, Isabel Natividad', u'Escudero D\xedaz-Tejeiro, Marta', u'Fermosel D\xedaz, Jes\xfas', u'Fern\xe1ndez-Quejo Del Pozo, Jos\xe9 Luis', u'Garc\xeda De Vinuesa Gardoqui, Ignacio', u'Garc\xeda Mart\xedn, Mar\xeda Bego\xf1a', u'Garrido Garc\xeda, \xc1ngel', u'G\xf3mez Ruiz, Jes\xfas', u'G\xf3mez-Angulo Rodr\xedguez, Juan Antonio', u'Gonz\xe1lez Gonz\xe1lez, Isabel Gema', u'Gonz\xe1lez Jim\xe9nez, Bartolom\xe9', u'Gonz\xe1lez Taboada, Jaime', u'Gonz\xe1lez-Mo\xf1ux V\xe1zquez, Elena', u'Gonzalo L\xf3pez, Rosal\xeda', 'Izquierdo Torres, Carlos', u'Li\xe9bana Montijano, Pilar', u'Mari\xf1o Ortega, Ana Isabel', u'Moraga Valiente, \xc1lvaro', u'Mu\xf1oz Abrines, Pedro', u'N\xfa\xf1ez Guijarro, Jos\xe9 Enrique', u'Olmo Fl\xf3rez, Luis Del', u'Ongil Cores, M\xaa Gador', 'Ortiz Espejo, Daniel', u'Ossorio Crespo, Enrique Mat\xedas', 'Peral Guerra, Luis', u'P\xe9rez Baos, Ana Isabel', u'P\xe9rez Garc\xeda, David', u'Pla\xf1iol De Lacalle, Regina M\xaa', u'Redondo Alcaide, M\xaa Isabel', u'Roll\xe1n Ojeda, Pedro', u'S\xe1nchez Fern\xe1ndez, Alejandro', 'Sanjuanbenito Bonal, Diego', u'Serrano Guio, Jos\xe9 Tom\xe1s', u'Serrano S\xe1nchez-Capuchino, Alfonso Carlos', 'Soler-Espiauba Gallo, Juan', 'Toledo Moreno, Lucila', 'Van-Halen Acedo, Juan']
[u'Andaluz Andaluz, M\xaa Isabel', u'Ardid Jim\xe9nez, M\xaa Isabel', u'Carazo G\xf3mez, M\xf3nica', u'Casares D\xedaz, M\xaa Luc\xeda Inmaculada', u'Cepeda Garc\xeda De Le\xf3n, Jos\xe9 Carmelo', 'Cruz Torrijos, Diego', u'Delgado G\xf3mez, Carla', u'Franco Pardo, Jos\xe9 Manuel', u'Freire Campo, Jos\xe9 Manuel', u'Gabilondo Pujol, \xc1ngel', 'Gallizo Llamas, Mercedes', u"Garc\xeda D'Atri, Ana", u'Garc\xeda-Rojo Garrido, Pedro Pablo', u'G\xf3mez Montoya, Rafael', u'G\xf3mez-Chamorro Torres, Jos\xe9 \xc1ngel', u'Gonz\xe1lez Gonz\xe1lez, M\xf3nica Silvana', u'Leal Fern\xe1ndez, M\xaa Isaura', u'Llop Cuenca, M\xaa Pilar', 'Lobato Gandarias, Juan', u'L\xf3pez Ruiz, M\xaa Carmen', u'Manguan Valderrama, Eva M\xaa', u'Maroto Illera, M\xaa Reyes', u'Mart\xednez Ten, Carmen', u'Mena Romero, M\xaa Carmen', u'Moreno Navarro, Juan Jos\xe9', u'Moya Nieto, Encarnaci\xf3n', 'Navarro Lanchas, Josefa', 'Nolla Estrada, Modesto', 'Pardo Ortiz, Josefa Dolores', u'Quintana Viar, Jos\xe9', u'Rico Garc\xeda-Hierro, Enrique', u'Rodr\xedguez Garc\xeda, Nicol\xe1s', u'S\xe1nchez Acera, Pilar', u'Sant\xedn Fern\xe1ndez, Pedro', 'Segovia Noriega, Juan', 'Vicente Viondi, Daniel', u'Vinagre Alc\xe1zar, Agust\xedn']
['Abasolo Pozas, Olga', 'Ardanuy Pizarro, Miguel', u'Beirak Ulanosky, Jazm\xedn', u'Camargo Fern\xe1ndez, Ra\xfal', 'Candela Pokorna, Marco', 'Delgado Orgaz, Emilio', u'D\xedaz Rom\xe1n, Laura', u'Espinar Merino, Ram\xf3n', u'Espinosa De La Llave, Mar\xeda', u'Fern\xe1ndez Rubi\xf1o, Eduardo', u'Garc\xeda G\xf3mez, M\xf3nica', 'Gimeno Reinoso, Beatriz', u'Guti\xe9rrez Benito, Eduardo', 'Huerta Bravo, Raquel', u'L\xf3pez Hern\xe1ndez, Isidro', u'L\xf3pez Rodrigo, Jos\xe9 Manuel', u'Mart\xednez Abarca, Hugo', u'Morano Gonz\xe1lez, Jacinto', u'Ongil L\xf3pez, Miguel', 'Padilla Estrada, Pablo', u'Ruiz-Huerta Garc\xeda De Viedma, Lorena', 'Salazar-Alonso Revuelta, Cecilia', u'San Jos\xe9 P\xe9rez, Carmen', u'S\xe1nchez P\xe9rez, Alejandro', u'Serra S\xe1nchez, Isabel', u'Serra S\xe1nchez, Clara', 'Sevillano De Las Heras, Elena']
[u'Aguado Crespo, Ignacio Jes\xfas', u'\xc1lvarez Cabo, Daniel', u'Gonz\xe1lez Pastor, Dolores', u'Iglesia Vicente, M\xaa Teresa De La', 'Lara Casanova, Francisco', u'Marb\xe1n De Frutos, Marta', u'Marcos Arias, Tom\xe1s', u'Meg\xedas Morales, Jes\xfas Ricardo', u'N\xfa\xf1ez S\xe1nchez, Roberto', 'Reyero Zubiri, Alberto', u'Rodr\xedguez Dur\xe1n, Ana', u'Rubio Ruiz, Juan Ram\xf3n', u'Ruiz Fern\xe1ndez, Esther', u'Sol\xeds P\xe9rez, Susana', 'Trinidad Martos, Juan', 'Veloso Lozano, Enrique', u'Zafra Hern\xe1ndez, C\xe9sar']

You can add the exact same logic to your spider, I just used requests to show you a working example. You should also be aware that not every asp.net site behaves the same, you may have to re-validate for every post as in this related answer.