[GIS] ArcGIS Rest performing query on feature service layers using within and intercepts

arcgis-rest-apiarcgis-servercfeature-servicerest

I am creating an application that needs to query a bunch of layers over REST to see which layers a point or line is within.

At the moment I have a local ArcGIS server set up with some feature services published. I can successfully connect to the services and retrieve results – I'm actually doing this from a C# application using a URL to query to feature service, then deserialising the JSON result.

Here is an example of how I am querying one of my services now:
http://LocalArcGisServer.local.com:6080/arcgis/rest/services/SW/SW_2/FeatureServer/0/query?f=json&where=PROJECT='EP'

Now the bit I am struggling with. I have points and lines defined that I want to test against some layers in various feature services. For example, I want to see if my point is within a particular polygon, or if my line crosses a polygon.

How can I formulate a query to a REST service, passing in my point or line, and asking if that point is within the layer or not?

I think I need to pass in info to describe my input point or line, and ask the feature service to do a 'Within' or 'Intercepts' query. What are the parameters I need to set, or how would I reformulate that query?

Best Answer

Ok, I figured out how to do this.

As Stefan suggested, I had to add a couple of parameters to the URL:

geometry (value = e.g. 639739.5,7598259.3)

geometryType (value = esriGeometryPoint)

spatialRel (value = esriSpatialRelWithin)

Here is an example call: http://LocalArcGisServer.local.com:6080/arcgis/rest/services/SW/SW2/FeatureServer/2/query?f=json&geometry=**639739.5,7598259.3&**geometryType=esriGeometryPoint&spatialRel=esriSpatialRelWithin&returnGeometry=false";

If you do not need the geometry of the polygon which the point falls into, you need to set returnGeometry as false. It works very nicely indeed!

Here is a good example of using REST from C# to talk to an ArcGis Feature service: http://rexdotnet.blogspot.com.au/2009/11/using-arcgis-server-rest-api-in-net.html

Hope this mighthelp someone else too.

Cheers!

Related Solutions

[GIS] ArcGIS Feature Service – Return a Single Row / Record

If you wanna to get only 1 record try use TOP statement.

ie: OBJECTID IN (SELECT TOP 1 OBJECTID FROM 'customers' ORDER BY OBJECTID))

but you have note that this is bypass because TOP and LIMIT arent supported by geodatabase http://forums.arcgis.com/threads/68997-TOP-100

EDIT I digged deeper cause this subject seems to me as interesting, and I found this kind of script: http://resources.arcgis.com/gallery/file/geoprocessing/details?entryID=E780BB87-1422-2418-7FD8-A1A0D8167AAF it returns a subset of features with the same schema as oryginal. It's made in python so, maybe you could use it as geoprocessing service as gate to your sql queries.

EDIT2 From more research i think that using TOP LIMIT or ROWNUM depends on your DB engine. But the main clue is to use it as subquery - because we only can get access from WHERE part of statement by using API

NOTE FOR 10.2 USERS: This will not work because it defaults to standardized queries which don't allow subqueries. You can turn off standardized queries, but this is not recommended since it makes SQL injection attacks easier to perform.

Python GeoPandas – Querying ESRI ArcGIS REST API Feature Service

The easiest way to create a query to an ArcGIS service is to first use the HTML interface, i.e. open https://dpw.gis.lacounty.gov/dpw/rest/services/PW_Open_Data/MapServer/22/query in a browser, and then inspect the URL it creates after you click on the Query (GET) button.

Documentation for all query parameters can be found here.

The URL will contain a lot of unused parameters that you can ignore in many cases. For the most basic query, you only need to set the following parameters:

Where: 1=1 (return all features)
Out fields: * (return all fields)
Format: json (or pjson to get a nice readable json format, or even geojson if that suits your needs)
Return ID's only: False

So, the URL would be https://dpw.gis.lacounty.gov/dpw/rest/services/PW_Open_Data/MapServer/22/query?f=json&outfields=*&where=1%3D1

Most REST services will limit the returned data on an open query like the one just described. However, once you have the top 1000 rows you can see all the available data. One key piece of data which you might not have yet is the coordinate reference system (CRS). This is in the returned data as "wkid": 102645. You can read about this reference system here: http://epsg.io/102645.

Here is a screenshot of what that query returns in a JSON format and with the well known ID (CRS) highlighted.

There are two ways to query features nearby a certain location. The easiest way is to specify a point and a distance, but not all services support this option. In the geometry below, the units are in the native CRS 102645. If you want to use the latitude and longitude from Google Maps, you will need to declare the CRS you are using in the input field "Input spatial Reference" as 4326.

Geometry: 6560874.3,1863451.1
Geometry Type: Point
Query By Distance: Any distance
Units: e.g. esriSRUnit_Meter
The Where option can be omitted if a geometry is set.

Note that the HTML interface incorrectly sets the name of the distance parameter to queryByDistance, and that it doesn't provide a field to set the units. Example: https://dpw.gis.lacounty.gov/dpw/rest/services/PW_Open_Data/MapServer/22/query?f=json&outfields=*&geometry=6560874.3,1863451.1&geometryType=esriGeometryPoint&distance=100&units=esriSRUnit_Meter

The other way is to generate a buffer around a point, and use that as geometry. This option should be supported by most, if not all, services. You may have to use a POST request rather than GET, because the URL may become too long due to the size of the geometries JSON.

Geometry: {"rings":[[[6560878,1863351],[6560869,1863351],[6560861,1863351],[6560852,1863353],[6560843,1863355],[6560835,1863358],[6560827,1863362],[6560819,1863367],[6560812,1863372],[6560805,1863378],[6560799,1863384],[6560794,1863391],[6560789,1863398],[6560784,1863406],[6560781,1863414],[6560778,1863422],[6560776,1863431],[6560774,1863440],[6560774,1863448],[6560774,1863457],[6560775,1863466],[6560777,1863475],[6560779,1863483],[6560783,1863491],[6560786,1863499],[6560791,1863507],[6560796,1863514],[6560802,1863521],[6560809,1863527],[6560816,1863532],[6560823,1863537],[6560831,1863541],[6560839,1863544],[6560848,1863547],[6560856,1863549],[6560865,1863550],[6560874,1863551],[6560883,1863550],[6560891,1863549],[6560900,1863547],[6560908,1863544],[6560917,1863541],[6560924,1863537],[6560932,1863532],[6560939,1863527],[6560945,1863521],[6560951,1863514],[6560956,1863507],[6560961,1863499],[6560965,1863491],[6560968,1863483],[6560971,1863475],[6560973,1863466],[6560974,1863457],[6560974,1863448],[6560973,1863440],[6560972,1863431],[6560970,1863422],[6560967,1863414],[6560963,1863406],[6560959,1863398],[6560954,1863391],[6560948,1863384],[6560942,1863378],[6560935,1863372],[6560928,1863367],[6560921,1863362],[6560913,1863358],[6560904,1863355],[6560896,1863353],[6560887,1863351],[6560878,1863351]]]}
Geometry Type: Polygon

Example: https://dpw.gis.lacounty.gov/dpw/rest/services/PW_Open_Data/MapServer/22/query?f=json&outfields=*&geometry=%7B%22rings%22%3A%5B%5B%5B6560878,1863351%5D,%5B6560869,1863351%5D,%5B6560861,1863351%5D,%5B6560852,1863353%5D,%5B6560843,1863355%5D,%5B6560835,1863358%5D,%5B6560827,1863362%5D,%5B6560819,1863367%5D,%5B6560812,1863372%5D,%5B6560805,1863378%5D,%5B6560799,1863384%5D,%5B6560794,1863391%5D,%5B6560789,1863398%5D,%5B6560784,1863406%5D,%5B6560781,1863414%5D,%5B6560778,1863422%5D,%5B6560776,1863431%5D,%5B6560774,1863440%5D,%5B6560774,1863448%5D,%5B6560774,1863457%5D,%5B6560775,1863466%5D,%5B6560777,1863475%5D,%5B6560779,1863483%5D,%5B6560783,1863491%5D,%5B6560786,1863499%5D,%5B6560791,1863507%5D,%5B6560796,1863514%5D,%5B6560802,1863521%5D,%5B6560809,1863527%5D,%5B6560816,1863532%5D,%5B6560823,1863537%5D,%5B6560831,1863541%5D,%5B6560839,1863544%5D,%5B6560848,1863547%5D,%5B6560856,1863549%5D,%5B6560865,1863550%5D,%5B6560874,1863551%5D,%5B6560883,1863550%5D,%5B6560891,1863549%5D,%5B6560900,1863547%5D,%5B6560908,1863544%5D,%5B6560917,1863541%5D,%5B6560924,1863537%5D,%5B6560932,1863532%5D,%5B6560939,1863527%5D,%5B6560945,1863521%5D,%5B6560951,1863514%5D,%5B6560956,1863507%5D,%5B6560961,1863499%5D,%5B6560965,1863491%5D,%5B6560968,1863483%5D,%5B6560971,1863475%5D,%5B6560973,1863466%5D,%5B6560974,1863457%5D,%5B6560974,1863448%5D,%5B6560973,1863440%5D,%5B6560972,1863431%5D,%5B6560970,1863422%5D,%5B6560967,1863414%5D,%5B6560963,1863406%5D,%5B6560959,1863398%5D,%5B6560954,1863391%5D,%5B6560948,1863384%5D,%5B6560942,1863378%5D,%5B6560935,1863372%5D,%5B6560928,1863367%5D,%5B6560921,1863362%5D,%5B6560913,1863358%5D,%5B6560904,1863355%5D,%5B6560896,1863353%5D,%5B6560887,1863351%5D,%5B6560878,1863351%5D%5D%5D%7D&geometryType=esriGeometryPolygon

If you want to use python to build a query, here's how.

import requests
import urllib.parse
import geopandas as gpd

url_base = r'https://dpw.gis.lacounty.gov/dpw/rest/services/PW_Open_Data/MapServer/22/query?'

Note the addition of the ? at the end of the URL.

Now define all your parameters.

params = {
    'geometry': '-118.21637221791077, 34.094916196179504',
    'geometryType': 'esriGeometryPoint',
    'inSR': '4326',
    'distance': '10000', 
    'units': 'esriSRUnit_Meter', 
    'returnGeometry': 'true', 
    'outFields': 'OBJECTID,DIVISION,FACILITY_N,ADDRESS,CITY', 
    'f': 'pjson'
}

Encode the URL:

url_final = url_base + urllib.parse.urlencode(params)

Use requests to query the server:

response = requests.get(url=url_final)

Convert the response to text so geopandas can read it:

data = response.text

Now load it into a geodataframe:

gdf_temp = gpd.read_file(data)

Best Answer

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[GIS] ArcGIS Feature Service – Return a Single Row / Record

Python GeoPandas – Querying ESRI ArcGIS REST API Feature Service

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