Layers have a single endpoint for requesting features. The /query supports filtering by attributes, geography, time, as well as aggregate statistics.

Defaults

To request all the data, up to the maximum record count, you need to provide a few required parameters:

.../FeatureServer/0/query?where=1=1&outFields=*&f=json

This request states: “Return all the features all the attributes as JSON.”


Formats

GeoServices support a few common formats. Most commonly these are html and json and depending on the version of Service can include geojson, kml, and amf. Format outputs are requested by using the URI parameter f={format}. html is the default response.

.../Education_WebMercator/MapServer/5?f=json


Filter by Attributes

Examples

Total number of students by school type and number of zipcodes that have this school type:

http://maps2.dcgis.dc.gov/dcgis/rest/services/DCGIS_DATA/Education_WebMercator/MapServer/5/query
  ?where=FACUSE like 'Elementary School' AND ZIP_CODE=20002 AND STATUS='Active'
  &outFields=*
  &f=json

See API Response

Parameters

Parameter Description Example
where SQL-like string of boolean operators FACUSE like ‘Elementary’ AND ZIP_CODE=20002

Filter by Location

Example

Single point location:

http://tigerweb.geo.census.gov/arcgis/rest/services/TIGERweb/Places_CouSub_ConCity_SubMCD/MapServer/15/query
    ?outFields=*
    &geometryType=esriGeometryPoint
    &geometry=-77.06930,38.89733
    &inSR=4326
    &f=json

Extent area:

http://maps2.dcgis.dc.gov/dcgis/rest/services/DCGIS_DATA/Education_WebMercator/MapServer/5/query
?where=FACUSE like '%Elementary%' AND TOTAL_STUD >= 200 AND TOTAL_STUD <= 1000
&geometry={"xmin":-77.0036,"ymin":38.8879,"xmax":-76.98434,"ymax":38.90007,"spatialReference":{"wkid":4326}}
&geometryType=esriGeometryEnvelope
&inSR=4326
&outFields=*

Parameters

Parameter Description Example
geometryType Point, Line or Polygon request esriGeometryPoint
geometry Longitude, Latitude pair or JSON -77.06930,38.89733
inSR Spatial reference of input geometry 4326

Aggregation Statistics

Examples

Total number of students by school type and number of zipcodes that have this school type:

http://maps2.dcgis.dc.gov/dcgis/rest/services/DCGIS_DATA/Education_WebMercator/MapServer/5/query
  ?groupByFieldsForStatistics=FACUSE,
  &outStatistics= [{
        "statisticType": "sum", 
        "onStatisticField": "TOTAL_STUD", 
        "outStatisticFieldName": "TOTAL_STUD_SUM"
      },{
        "statisticType": "count", 
        "onStatisticField": "ZIP_CODE", 
        "outStatisticFieldName": "ZIP_CODE_COUNT"
      }]
  &where=1=1
  &outFields=*
  &f=json

See API Response

Parameters

Parameter Description Example
groupByFieldsForStatistics Attribute to use as key for aggregation ZIP_CODE
outStatistics Array of statistics calculations. Can be one or many [{"statisticType": "sum", "onStatisticField": "TOTAL_STUD", "outStatisticFieldName": "TOTAL_STUD_SUM"}]
outStatistics.statisticType Type of Statistic to calculate: count,sum, avg, var, max, min sum
outStatistics.onStatisticField Layer attribute to use with statistic type NUM_STUDENTS
outStatistics.outStatisticFieldName Name to use for the field NUM_STUDENTS_SUM