[HELP] Unable to retrieve data from RESTful sensor using json_attributes

Configuration
1

I am trying to build my first custom RESTful sensor for integrating data from Surfline onto my dashboard, but I can’t seem to access the data with json_attributes.

In my sensors.yaml file, which is included by my configuration.yaml file as sensor: !include sensors.yaml

- platform: rest
  resource: https://services.surfline.com/kbyg/regions/forecasts/conditions?spotId=5842041f4e65fad6a7708b8d&days=1
  method: GET
  name: surfline
  value_template: '{{ (value_json["data"].conditions[0]) }}'
  json_attributes_path: "$.data.conditions[0]"
  json_attributes:
    - am
    - pm
    - observation
  scan_interval: 900
- platform: template
  sensors:
    surfline_am:
      friendly_name: "AM"
      value_template: "{{ state_attr('sensor.surfline', 'am')['maxHeight']}}"
    surfline_pm:
      friendly_name: "PM"
      value_template: "{{ state_attr('sensor.surfline', 'pm') }}"
    surfline_observation:
      friendly_name: "Observation"
      value_template: "{{ state_attr('sensor.surfline', 'observation') }}"

And here is the JSON response from the API (or you can try it yourself, no authentication is required)

// Unnecessary data omitted for brevity
{
  "associated": {
  },
  "data": {
    "conditions": [
      {
        "observation": "Very small very short period waves from the SW. Light WSW winds with semi clean to slightly sideshore textured conditions.",
        "am": {
          "maxHeight": 2,
          "minHeight": 1,
        },
        "pm": {
          "maxHeight": 1,
          "minHeight": 0.5,
        }
      }
    ]
  }
}

I’ve tried eliminating the json_attributes_path and just making the attribute ‘data’, amongst several other things, and just can’t seem to get it to work. Any help? The state says ‘Unknown’ with my current configuration.

2

In HA, states cannot be more than 255 characters, while attributes do not have size constraints.
Your value_template: '{{ (value_json["data"].conditions[0]) }}'returns more than that.

Typically, for JSON RESTfull sensors, value_json is set to OK (value_template: "OK") and only attributes are used.