NWS Client

A Crystal library for querying the United States' National Weather Service API.

Installation

1. Add the dependency to your shard.yml:

   dependencies:
     nws-client:
       github: dscottboggs/nws-client
   

2. Run shards install

Usage

require "nws-client/gridpoints/forecast"

NWSClient.gridpoints("PBZ", 74, 68)
  .forecast
  .properties
  .periods
  .each do |forecast|
    puts "it will be #{forecast.temperature} #{forecast.name}"
  end

Output:

it will be 81 Today
it will be 62 Tonight
it will be 82 Tuesday
it will be 58 Tuesday Night
it will be 82 Wednesday
it will be 58 Wednesday Night
it will be 86 Thursday
it will be 62 Thursday Night
it will be 89 Friday
it will be 65 Friday Night
it will be 88 Saturday
it will be 65 Saturday Night
it will be 85 Sunday
it will be 64 Sunday Night

Development

Not all API endpoints are currently implemented. If you need to query an endpoint which hasn't been implemented yet, the procedure for implementing it is:

1. Download a sample(s) from the endpoint you want to be able to query from Crystal

curl -L api.weather.gov/gridpoints/PBZ/74,68/forecast > src/types/gridpoints_forecast.json

2. Run jenerator on the downloaded sample(s).

cd samples
jenerator .

3. Write a spec for the new type, based on the existing examples in the spec dir, which tests that your generated types successfully parse the sample you downloaded.

4. Edit the generated file(s) until the specs pass. This involves removing redundant ArrayMember types, and changing any Nil types to the optional of what they're expected to be (i.e. String? or Float64?). This may include pulling class definitions from nested structures other redundant ArrayMember types. This is definitely the hardest part of the process, but it should only take a few minutes.

5. Add a fetch class method to your type:

   • If your query can be constant, assign it to FETCH_PATH in your type, and include APIHelper. See src/types/alerts.cr for an example.
   • If your query needs some parameters, define a custom fetch method like in src/types/gridpoints_forecast.cr

6. Add a convenience class method to the NWSClient in src/nws-client/. This method and any support types should be defined in a single file in that folder. For example:

   • alerts queries should be requirable with require "nws-client/alerts"
   • all queries related to gridpoints should be requirable with require "nws-client/gridpoints", while the forecasts for a gridpoint should be able to be required with require "nws-client/gridpoints/forecast".

   These client files should only require the types under src/types/ which are needed to make a given request.

Contributing

1. Fork it (https://github.com/dscottboggs/nws-client/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• D. Scott Boggs - creator and maintainer