JSONDecodeError When Accessing a Feature Layer

J_R_Matchett

I'm trying to query a particular feature layer (https://www.visalia.city/server/rest/services/OpenData/CurrentAddresses/FeatureServer/0)

but receive a JSONDecodeError. Here's my code and result:

<SPAN class="keyword token">from</SPAN> arcgis<SPAN class="punctuation token">.</SPAN>features <SPAN class="keyword token">import</SPAN> FeatureLayer

adds_layer <SPAN class="operator token">=</SPAN> FeatureLayer<SPAN class="punctuation token">(</SPAN><SPAN class="string token">'https://www.visalia.city/server/rest/services/OpenData/CurrentAddresses/FeatureServer/0'</SPAN><SPAN class="punctuation token">)</SPAN>

adds <SPAN class="operator token">=</SPAN> adds_layer<SPAN class="punctuation token">.</SPAN>query<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN>

Traceback <SPAN class="punctuation token">(</SPAN>most recent call last<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN>
  File <SPAN class="string token">"<stdin>"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">1</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> <SPAN class="operator token"><</SPAN>module<SPAN class="operator token">></SPAN>
  File <SPAN class="string token">"/Users/jrmatchett/opt/anaconda3/envs/arcgis17/lib/python3.7/site-packages/arcgis/features/layer.py"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">1019</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> query
    record_count <SPAN class="operator token">=</SPAN> self<SPAN class="punctuation token">.</SPAN>_query<SPAN class="punctuation token">(</SPAN>url<SPAN class="punctuation token">,</SPAN> params<SPAN class="punctuation token">,</SPAN> raw<SPAN class="operator token">=</SPAN>as_raw<SPAN class="punctuation token">)</SPAN>
  File <SPAN class="string token">"/Users/jrmatchett/opt/anaconda3/envs/arcgis17/lib/python3.7/site-packages/arcgis/features/layer.py"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">1960</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> _query
    <SPAN class="keyword token">raise</SPAN> queryException
  File <SPAN class="string token">"/Users/jrmatchett/opt/anaconda3/envs/arcgis17/lib/python3.7/site-packages/arcgis/features/layer.py"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">1930</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> _query
    postdata<SPAN class="operator token">=</SPAN>params<SPAN class="punctuation token">,</SPAN> token<SPAN class="operator token">=</SPAN>self<SPAN class="punctuation token">.</SPAN>_token<SPAN class="punctuation token">)</SPAN>
  File <SPAN class="string token">"/Users/jrmatchett/opt/anaconda3/envs/arcgis17/lib/python3.7/site-packages/arcgis/gis/__init__.py"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">10101</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> _token
    self<SPAN class="punctuation token">.</SPAN>_hydrate<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN>
  File <SPAN class="string token">"/Users/jrmatchett/opt/anaconda3/envs/arcgis17/lib/python3.7/site-packages/arcgis/gis/__init__.py"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">10071</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> _hydrate
    self<SPAN class="punctuation token">.</SPAN>_refresh<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN>
  File <SPAN class="string token">"/Users/jrmatchett/opt/anaconda3/envs/arcgis17/lib/python3.7/site-packages/arcgis/gis/__init__.py"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">10038</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> _refresh
    <SPAN class="keyword token">raise</SPAN> e
  File <SPAN class="string token">"/Users/jrmatchett/opt/anaconda3/envs/arcgis17/lib/python3.7/site-packages/arcgis/gis/__init__.py"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">10033</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> _refresh
    dictdata <SPAN class="operator token">=</SPAN> self<SPAN class="punctuation token">.</SPAN>_con<SPAN class="punctuation token">.</SPAN>post<SPAN class="punctuation token">(</SPAN>self<SPAN class="punctuation token">.</SPAN>url<SPAN class="punctuation token">,</SPAN> params<SPAN class="punctuation token">,</SPAN> token<SPAN class="operator token">=</SPAN>self<SPAN class="punctuation token">.</SPAN>_lazy_token<SPAN class="punctuation token">)</SPAN>
  File <SPAN class="string token">"/Users/jrmatchett/opt/anaconda3/envs/arcgis17/lib/python3.7/site-packages/arcgis/_impl/connection.py"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">1148</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> post
    resp_json <SPAN class="operator token">=</SPAN> json<SPAN class="punctuation token">.</SPAN>loads<SPAN class="punctuation token">(</SPAN>resp_data<SPAN class="punctuation token">)</SPAN>
  File <SPAN class="string token">"/Users/jrmatchett/opt/anaconda3/envs/arcgis17/lib/python3.7/json/__init__.py"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">348</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> loads
    <SPAN class="keyword token">return</SPAN> _default_decoder<SPAN class="punctuation token">.</SPAN>decode<SPAN class="punctuation token">(</SPAN>s<SPAN class="punctuation token">)</SPAN>
  File <SPAN class="string token">"/Users/jrmatchett/opt/anaconda3/envs/arcgis17/lib/python3.7/json/decoder.py"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">337</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> decode
    obj<SPAN class="punctuation token">,</SPAN> end <SPAN class="operator token">=</SPAN> self<SPAN class="punctuation token">.</SPAN>raw_decode<SPAN class="punctuation token">(</SPAN>s<SPAN class="punctuation token">,</SPAN> idx<SPAN class="operator token">=</SPAN>_w<SPAN class="punctuation token">(</SPAN>s<SPAN class="punctuation token">,</SPAN> <SPAN class="number token">0</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">.</SPAN>end<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN>
  File <SPAN class="string token">"/Users/jrmatchett/opt/anaconda3/envs/arcgis17/lib/python3.7/json/decoder.py"</SPAN><SPAN class="punctuation token">,</SPAN> line <SPAN class="number token">355</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">in</SPAN> raw_decode
    <SPAN class="keyword token">raise</SPAN> JSONDecodeError<SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Expecting value"</SPAN><SPAN class="punctuation token">,</SPAN> s<SPAN class="punctuation token">,</SPAN> err<SPAN class="punctuation token">.</SPAN>value<SPAN class="punctuation token">)</SPAN> <SPAN class="keyword token">from</SPAN> None
json<SPAN class="punctuation token">.</SPAN>decoder<SPAN class="punctuation token">.</SPAN>JSONDecodeError<SPAN class="punctuation token">:</SPAN> Expecting value<SPAN class="punctuation token">:</SPAN> line <SPAN class="number token">1</SPAN> column <SPAN class="number token">1</SPAN> <SPAN class="punctuation token">(</SPAN>char <SPAN class="number token">0</SPAN><SPAN class="punctuation token">)</SPAN>
<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

I can access and query the layer just fine via its webpage or when adding it to a web map. Accessing some other feature layer properties, such as properties and metadata, generates the same error. I experience the issue when using either versions 1.6.2 or 1.7.1 of the arcgis python API.

bixb0012

This question/issue intrigued me, so I spent some time last night looking into it.

The security service/device is definitely responsible for the inability of the ArcGIS API for Python to query the GIS services on the site.  The site requires both full cookie and Javascript support, the latter being the challenge for the ArcGIS API for Python.  There might be a way to get special cookie and session information in a browser and then copy it over to the ArcGIS API for Python, but it would be a bit hack-y/messy even if you could get it work.