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Elixir Socrata Client

This library is intended to be as transparent a wrapper as possible for the Socrata SODA 2.1+ API.

Installation

This library is available via Hex. To add it as a dependency to your application, add the following to your mix.exs file:

defp deps do
  [
    {:socrata, "~> 2.0.0"}
  ]
end

Configuration

There are two optional configuration values that you can supply via your application's config/config.exs file:

config :socrata,
  default_format: "json",
  app_token: "blah blah blah"

Using the default_format config sets a default response type for all of your requests. This can be overwritten when calling client functions with the format option.

Using the app_token add the X-App-Token header to all of your requests. Having a token greatly increases your rate limit. For more information about tokens, see the Socrata App Tokens docs.

Reading Data from the API

There are two endpoints that the Socrata.Client module will work with:

  • the views endpoint to get data set metadata
  • the resources endpoint to get data set records

Metadata Client Example

alias Socrata.{Client, Query}

query = Query.new(fourby: "yama-9had", domain: "data.cityofchicago.org")

{:ok, %HTTPoison.Response{body: body}} = Client.get_view(query)
details = Jason.decode!(body)

Map.keys(details)
# ["oid", "publicationAppendEnabled", "category", "numberOfComments",
#  "createdAt", "attribution", "hideFromDataJson", "query", "id",
#  "tableAuthor", "rights", "tableId", "attributionLink", "owner",
#  "viewCount", "grants", "downloadCount", "flags", "publicationGroup",
#  "name", "averageRating", "publicationDate", "hideFromCatalog",
#  "provenance", "totalTimesRated", "description", "metadata",
#  "viewLastModified", "rowsUpdatedAt", "rowsUpdatedBy", "viewType",
#  "newBackend", "publicationStage", "tags", "columns"]

Getting Records as JSON

By default, calling Socrata.Client.get_records/4 will use the .json API syntax and the response body will be encoded JSON.

alias Socrata.{Client, Query}

query = Query.new("yama-9had", "data.cityofchicago.org") |> Query.limit(2)

{:ok, %HTTPoison.Response{body: body}} = Client.get_records(query)
records = Jason.decode!(body)

length(records)
# 2

Getting Records as CSV

You can provide a third argument to Socrata.Client.get_records/4 to specify the API response syntax. In this case, we'll set it to "csv" and get back an encoded CSV document in the response body.

alias Socrata.{Client, Query}

query = Query.new("yama-9had", "data.cityofchicago.org") |> Query.limit(2)

{:ok, %HTTPoison.Response{body: body}} = Client.get_records(query, format: "csv")
{:ok, stream} = StringIO.open(body)
records =
  IO.binstream(stream, :line)
  |> CSV.decode!(headers: true)
  |> Enum.map(& &1)

length(records)
# 2

Getting Records as TSV

You can provide a third argument to Socrata.Client.get_records/4 to specify the API response syntax. In this case, we'll set it to "tsv" and get back an encoded TSV document in the response body.

alias Socrata.{Client, Query}

query = Query.new("yama-9had", "data.cityofchicago.org") |> Query.limit(2)

{:ok, %HTTPoison.Response{body: body}} = Client.get_records(query, format: "tsv")

{:ok, stream} = StringIO.open(body)

records =
  IO.binstream(stream, :line)
  |> CSV.decode!(separator: ?\\t, headers: true)
  |> Enum.map(& &1)

length(records)
# 2

Getting Records as GeoJSON

You can provide a third argument to Socrata.Client.get_records/4 to specify the API response syntax. In this case, we'll set it to "geojson" and get back an encoded GeoJSON document in the response body.

alias Socrata.{Client, Query}

query = Query.new("yama-9had", "data.cityofchicago.org") |> Query.limit(2)

{:ok, %HTTPoison.Response{body: body}} = Client.get_records(query, format: "geojson")
%{"crs" => _, "type" => "FeatureCollection", "features" => records} = Jason.decode!(body)

length(records)
# 2

Passing HTTPoison Options

The fourth parameter of Socrata.Client.get_records/4 is a keyword list of options that are directly dumped to the call to HTTPoison.get!/3 under the hood.

By doing this, the library hands over full control of the request/response life cycle to you. By default it sends the request as a standard, synchronous blocking call that gets a complete response object.

  alias Socrata.{Client, Query}

  query = Query.new("yama-9had", "data.cityofchicago.org") |> Query.limit(2)
  {:ok, %HTTPoison.AsyncResponse{id: id}} = Client.get_records(query, stream_to: self())

  is_reference(id)
  # true