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what-to-wear

Build status License

what-to-wear is a service that periodically queries the openweathermap-API to get the latest weather data and generates a dynamic info display.

Together with ePaperDisplay it can be used as an e paper weather display.

The user can specify messages to be displayed based on weather criteria. Conditions are evaluated using the Expr expression language.

Installation

Besides the what-to-wear binary, a Chrome installation is required on the host.

Configuring

An example configuration can be found here.

Note that string expressions defined in the configuration file (such as message strings) require quotation marks to be evaluated by the expression language. Therefore, double quotations are required.

Website

The file templates/index.gohtml is a templated HTML file representing the website. It can be modified to customize the view.

Any other files to be served (e.g. webfonts, images, ...) can be added in the static folder and referenced from the main template.

Images

In addition to the website, the display data will also be available as image data. The images can either be received through http from the server or can be pushed through MQTT. Whenever an update is performed, a headless Chrome instance will be used to render the display, process, and push the data.

Messages

Messages can have conditions that determine if they are displayed or not:

- message: >
      "Better bring an <i class='fas fa-umbrella'></i>."
    condition: "weather.CumulativePrecipitationTill(todayAt(20)) > 0.5"

Variables can be defined that that can be built into the message string. Variables have different choices which are evaluated top to bottom (in case the conditions overlap).

- message: "'It would be best to wear a ' + top"
    condition: "currentTime.Hour() < 20"
    variables:
      - name: "top"
        choices:
          - expression: "weather.AverageFeelsLikeTill(todayAt(20)) > 20"
            value: "t-shirt"
          - expression: "weather.AverageFeelsLikeTill(todayAt(20)) <= 20"
            value: "sweatshirt"

The variable weather is an instance of WeatherData in go-owm and all its properties can be used for evaluation.

In addition, it is possible to call WeatherData helper functions such as:

Function Description
WeatherAt(referenceTime time.Time) *HourlyWeatherSlice returns the weather closest to referenceTime
CumulativePrecipitationTill(referenceTime time.Time) float64 returns the cumulative precipitation from the beginning of the data range till referenceTime
AverageTemperatureTill(referenceTime time.Time) float64 returns the average temperature from the beginning of the data range till referenceTime
AverageFeelsLikeTill(referenceTime time.Time) float64 returns the average feels like temperature from the beginning of the data range till referenceTime

To make handling of time easier, the following two helper functions are provided:

Function Description
hoursFromNow(hours int) time.Time Returns a Time object representing hours hours from now
todayAt(hour int) time.Time Returns a Time object representing hour time of day