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A simple example to download geography data of DETER Amazon project via WFS service using authentication.
"""
Download WFS
Download Shapefile DETER
Copyright 2020 TerraBrasilis
Usage:
download-deter-data.py
Options:
no have
Disclaimer.
This is an example, therefore, we do not implement all error handling or cover all
problems related to the download process.
It is highly recommended that you improve and adapt this code to your specifics.
If you run this script in the same directory on the same day, the output file will be replaced.
Before start, read the tecnical posts into our Blog.
http://terrabrasilis.dpi.inpe.br/categoria/conteudo-tecnico/
"""
import requests, os, io
from requests.auth import HTTPBasicAuth
from datetime import datetime
from xml.etree import ElementTree as xmlTree
class DownloadWFS:
"""
Define configurations on instantiate.
First parameter: user, The user name used to authentication on the server.
Second parameter: password, The password value used to authentication on the server.
To change the predefined settings, inside the constructor, edit the
parameter values ​​in accordance with the respective notes.
"""
def __init__(self,user=None,password=None):
"""
Constructor with predefined settings.
The start date is set by manually changing the value of the START_DATE parameter, below.
The end date is automatically detected in the machine's calendar.
The next filter on the states, uses the UF parameter and the
values ​​are the acronyms of the state names, like PA or AM.
Important note: If the range used to filter is very wide, the number of resources
returned may be greater than the maximum limit allowed by the server.
In this case, this version has been prepared for pagination and the shapefile is
downloaded in parts.
"""
# warning: before change the time interval, pay attention into notes on constructor.
self.START_DATE="2018-01-01"
self.END_DATE=datetime.today().strftime('%Y-%m-%d')
self.UF=None
self.WORKSPACE_NAME="deter-amz"
# To change the desired layer, change the following value.
# The public layer "deter_amz" or the controled layer "deter_amz_auth"
self.LAYER_NAME="deter_amz"
# The output file name (layer_name_start_date_end_date)
self.OUTPUT_FILENAME="{0}_{1}_{2}".format(self.LAYER_NAME,self.START_DATE,self.END_DATE)
self.AUTH=None
if user and password:
self.AUTH=HTTPBasicAuth(user, password)
def __buildBaseURL(self):
host="terrabrasilis.dpi.inpe.br"
url="http://{0}/geoserver/{1}/{2}/wfs".format(host,self.WORKSPACE_NAME,self.LAYER_NAME)
return url
def __buildQueryString(self, OUTPUTFORMAT=None):
"""
Building the query string to call the WFS service.
The parameter: OUTPUTFORMAT, the output format for the WFS GetFeature operation described
in the AllowedValues ​​section in the capabilities document.
<ows:Parameter name="outputFormat">
<ows:AllowedValues>
<ows:Value>application/gml+xml; version=3.2</ows:Value>
<ows:Value>GML2</ows:Value>
<ows:Value>KML</ows:Value>
<ows:Value>SHAPE-ZIP</ows:Value>
<ows:Value>application/json</ows:Value>
<ows:Value>application/vnd.google-earth.kml xml</ows:Value>
<ows:Value>application/vnd.google-earth.kml+xml</ows:Value>
<ows:Value>csv</ows:Value>
<ows:Value>gml3</ows:Value>
<ows:Value>gml32</ows:Value>
<ows:Value>json</ows:Value>
<ows:Value>text/xml; subtype=gml/2.1.2</ows:Value>
<ows:Value>text/xml; subtype=gml/3.1.1</ows:Value>
<ows:Value>text/xml; subtype=gml/3.2</ows:Value>
</ows:AllowedValues>
</ows:Parameter>
To change defined filters and discover more possibilities
you should learn more about WFS standard and how to filter using CQL.
https://www.ogc.org/standards/wfs
"""
# Filters example (by date interval and uf)
CQL_FILTER="view_date BETWEEN '{0}' AND '{1}'".format(self.START_DATE,self.END_DATE)
if self.UF: CQL_FILTER="{0} AND uf='{1}'".format(CQL_FILTER,self.UF)
# WFS parameters
SERVICE="WFS"
REQUEST="GetFeature"
VERSION="2.0.0"
# if OUTPUTFORMAT is changed, check the output file extension within the get method in this class.
OUTPUTFORMAT= ("SHAPE-ZIP" if not OUTPUTFORMAT else OUTPUTFORMAT)
exceptions="text/xml"
# define the output projection. We use the layer default projection. (Geography/SIRGAS2000)
srsName="EPSG:4674"
# the layer definition
TYPENAME="{0}:{1}".format(self.WORKSPACE_NAME,self.LAYER_NAME)
allLocalParams=locals()
allLocalParams.pop("self",None)
PARAMS="&".join("{}={}".format(k,v) for k,v in allLocalParams.items())
return PARAMS
def __xmlRequest(self, url):
root=None
if self.AUTH:
response=requests.get(url, auth=self.AUTH)
else:
response=requests.get(url)
if response.ok:
xmlInMemory = io.BytesIO(response.content)
tree = xmlTree.parse(xmlInMemory)
root = tree.getroot()
return root
def __getServerLimit(self):
"""
Read the data download service limit via WFS
"""
url="{0}?{1}".format(self.__buildBaseURL(),"service=wfs&version=2.0.0&request=GetCapabilities")
# the default limit on our GeoServer
serverLimit=100000
XML=self.__xmlRequest(url)
if XML.tag is not None and '{http://www.opengis.net/wfs/2.0}WFS_Capabilities'==XML.tag:
for p in XML.findall(".//{http://www.opengis.net/ows/1.1}Operation/[@name='GetFeature']"):
dv=p.find(".//{http://www.opengis.net/ows/1.1}Constraint/[@name='CountDefault']")
serverLimit=dv.find('.//{http://www.opengis.net/ows/1.1}DefaultValue').text
return int(serverLimit)
def __countMaxResult(self):
"""
Read the number of lines of results expected in the download using the defined filters.
"""
url="{0}?{1}".format(self.__buildBaseURL(), self.__buildQueryString())
url="{0}&{1}".format(url,"resultType=hits")
numberMatched=0
XML=self.__xmlRequest(url)
if XML.tag is not None and '{http://www.opengis.net/wfs/2.0}FeatureCollection'==XML.tag:
numberMatched=XML.find('[@numberMatched]').get('numberMatched')
return int(numberMatched)
def __pagination(self):
# get server limit and count max number of results
sl=self.__getServerLimit()
rr=self.__countMaxResult()
# define the start page number
pagNumber=1
# define the start index of data
startIndex=0
# define the attribute to sort data
sortBy="gid"
# using the server limit to each download
count=sl
# pagination iteraction
while(startIndex<rr):
paginationParams="&count={0}&sortBy={1}&startIndex={2}".format(count,sortBy,startIndex)
self.__download(paginationParams,pagNumber)
startIndex=startIndex+count
pagNumber=pagNumber+1
def __download(self, pagination="startIndex=0", pagNumber=1):
url="{0}?{1}&{2}".format(self.__buildBaseURL(), self.__buildQueryString(), pagination)
dir_name=os.path.realpath(os.path.dirname(__file__))
# the extension of output file is ".zip" because the OUTPUTFORMAT is defined as "SHAPE-ZIP"
output_file="{0}/{1}_part{2}.zip".format(dir_name, self.OUTPUT_FILENAME, pagNumber)
if self.AUTH:
response=requests.get(url, auth=self.AUTH)
else:
response=requests.get(url)
if response.ok:
with open(output_file, 'wb') as f:
f.write(response.content)
else:
print("Download fail with HTTP Error: {0}".format(response.status_code))
def get(self):
self.__pagination()
# end of class
# To call without credentials (uses the public layer name)
down=DownloadWFS()
# To call with credentials (needs change the layer name)
# down=DownloadWFS("user","pass")
# Call download
down.get()
@Wanhenri
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Boa tarde André, tudo bom?
Recentemente estou passou esse erro que não consigo solucionar:

wanderson.santos@terrama:/dados/terrama/volumes/terrama2_data_vol/_data/deter$python main.py
entrou
Traceback (most recent call last):
  File "main.py", line 57, in <module>
    main()
  File "main.py", line 35, in main
    import_deter()
  File "/dados/terrama/volumes/terrama2_data_vol/_data/deter/deter.py", line 240, in import_deter
    down.get()
  File "/dados/terrama/volumes/terrama2_data_vol/_data/deter/deter.py", line 227, in get
    self.__pagination()
  File "/dados/terrama/volumes/terrama2_data_vol/_data/deter/deter.py", line 191, in __pagination
    rr=self.__countMaxResult()
  File "/dados/terrama/volumes/terrama2_data_vol/_data/deter/deter.py", line 183, in __countMaxResult
    if '{http://www.opengis.net/wfs/2.0}FeatureCollection'==XML.tag:
AttributeError: 'NoneType' object has no attribute 'tag'
wanderson.santos@terrama:/dados/terrama/volumes/terrama2_data_vol/_data/deter$

Teria alguma ideia de como solucionar esse problema?

@andre-carvalho
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Author

Olá Wanderson, tudo certo, espero que com você também.
Este código não está bom com relação ao tratamento de exceções.
O problema está sendo gerado por uma alteração no nome dos atributos publicados na camada WFS em questão.
Troque o atributo "date" por "view_date" que o problema deve ser resolvido.
Vou corrigir o exemplo.
Abraço, André

@andre-carvalho
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Author

Olá Wanderson, veja a última revisão do código para identificar exatamente o local da alteração.
Grato pelo interesse, André

@Wanhenri
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Boa Noite André, tudo ótimo?
Excelente dica!!! Funcionou perfeitamente.

Muitíssimo obrigado pela ajuda.

@Wanhenri
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Boa tarde Andre, tudo bom?
Saberia dizer se mudaram a tag?...eu tinha pego a versão com a view_date (CQL_FILTER="view_date BETWEEN '{0}' AND '{1}'".format(self.START_DATE,self.END_DATE) porém esta dando novamente o erro de AttributeError: 'NoneType' object has no attribute 'tag'

Muito obrigado pela ajuda.

@andre-carvalho
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Author

Olá Wanderson,
Acredito que tenha relação com as instabilidades do serviço. Tivemos muitas quedas/desligamentos de energia especialmente em 07/09 e 13/09.
Testei aqui e continua funcionando.

Como informado no cabeçalho do script, os tratamentos de possíveis falhas precisam ser melhorados/adaptados.

Sugiro que você inclua a verificação de validade do membro "tag" do objeto "XML". Há necessidade em dois pontos, linha 156 e 172.

Tente usar assim:

if XML.tag is not None and

Incluí isso ao código, basta conferir.

Mas ainda não é o ideal, já que a execução irá continuar, utilizando os valores default para os limites. Caso o problema seja com o serviço remoto, irá parar mais à frente.

Abraço, André

@Wanhenri
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Boa tarde Andre, tudo bom?

Excelente dica! Funcionou perfeitamente.
Muitissimo obrigado pela ajuda.

Abraços,
Wanderson Santos

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