feature: Integrating MeteoBlue into the providers package

[yendelevium]

Feature Request

Summary

To integrate MB into the providers package

• Structure MB models and processes
• Unmarshal the data returned by MB into the baseData struct (plumber pkg)

Motivation

MB will be the primary provider for meteomunch, so proper integration is required. Then, the other data can be filled in by other providers like open-meteo, Copernicus etc

Detailed Design

The way baseData is structed, it has separate fields for current, hourly and daily data. MB's data is different, and it doesn't get cleanly translated into baseData.
We could create intermediate models for current, hourly and daily data, unmarshal MB data into all three separately, and then add them to the baseData struct.

Alternatives

• Remove the current, hourly, and daily nested structs from baseData, and directly store the fields we want into the baseData struct. This removes the intermediate structs proposed in the first solution, at the cost of bloating up the baseData struct.

Additional Context

We would also need to pass this struct around to other providers(if available) to fill in data MB missed or doesn't provide, and then return this data back to the service which called it. The faster we can do this, the better.
We should also be able to extract the hourly,daily, and current data (incase we decide to go with the alternative option, I'm assuming we can probably access them via the baseData struct if we go with the proposed solution)

Acceptance Criteria

• MB Data must be successfully translated to the baseData struct
• The hourly, daily, and current data must be accessible separately

Additional Information

References #5

[yendelevium]

Any alternative solutions and/or outcomes are welcome. Please express your thoughts @adofm @raamsri

[raamsri]

Good call Yash! Let's try to retain the idea of unmarshalling to BaseData struct until we run into roadblocks that break the design?

[raamsri]

At a higher level, assuming the relevant new fields from MB are added to BaseStruct, I tried a two fold approach to work around the root level fields' name mismatch for seamless marshalling/unmarshalling.

I reckon that it's easier to show the approach via code for this one, so please see if this snippet makes sense.

package main

import (
	"encoding/json"
	"fmt"
)

type MyStruct struct {
	Field string `json:"field"`
}

func (m *MyStruct) UnmarshalJSON(data []byte) error {
	type Alias MyStruct
	aux := &struct {
		*Alias
		AltField string `json:"alt_field"`
	}{Alias: (*Alias)(m)}

	if err := json.Unmarshal(data, aux); err != nil {
		return err
	}

	if aux.AltField != "" {
		m.Field = aux.AltField
	}

	return nil
}

func main() {
	jsonData1 := `{"field": "value1"}`
	jsonData2 := `{"alt_field": "value2"}`

	var obj1, obj2 MyStruct

	if err := json.Unmarshal([]byte(jsonData1), &obj1); err != nil {
		fmt.Println("Error unmarshalling jsonData1:", err)
	}
	if err := json.Unmarshal([]byte(jsonData2), &obj2); err != nil {
		fmt.Println("Error unmarshalling jsonData2:", err)
	}

	fmt.Println("obj1:", obj1.Field) 
	fmt.Println("obj2:", obj2.Field) 
}

Output:
obj1: value1
obj2: value2

[raamsri]

I have picked packages that are of most relevance from MB: basic-1h_basic-day_clouds-1h_clouds-day_air-1h_air-day_wind-1h_wind-day. So, this could be the APIPath for MB config.

QP would be apikey=xxxx&lat=10.9018379&lon=76.8998445&format=json&tz=GMT&forecast_days=1

The URI looks something like: https://my.meteoblue.com/packages/basic-1h_basic-day_clouds-1h_clouds-day_air-1h_air-day_wind-1h_wind-day?apikey=xxxx&lat=10.9018379&lon=76.8998445&format=json&tz=GMT&forecast_days=1

[JrGkOG]

we can start working on this @raamsri

[JrGkOG]

At a higher level, assuming the relevant new fields from MB are added to BaseStruct, I tried a two fold approach to work around the root level fields' name mismatch for seamless marshalling/unmarshalling.

I reckon that it's easier to show the approach via code for this one, so please see if this snippet makes sense.

package main

import (
	"encoding/json"
	"fmt"
)

type MyStruct struct {
	Field string `json:"field"`
}

func (m *MyStruct) UnmarshalJSON(data []byte) error {
	type Alias MyStruct
	aux := &struct {
		*Alias
		AltField string `json:"alt_field"`
	}{Alias: (*Alias)(m)}

	if err := json.Unmarshal(data, aux); err != nil {
		return err
	}

	if aux.AltField != "" {
		m.Field = aux.AltField
	}

	return nil
}

func main() {
	jsonData1 := `{"field": "value1"}`
	jsonData2 := `{"alt_field": "value2"}`

	var obj1, obj2 MyStruct

	if err := json.Unmarshal([]byte(jsonData1), &obj1); err != nil {
		fmt.Println("Error unmarshalling jsonData1:", err)
	}
	if err := json.Unmarshal([]byte(jsonData2), &obj2); err != nil {
		fmt.Println("Error unmarshalling jsonData2:", err)
	}

	fmt.Println("obj1:", obj1.Field) 
	fmt.Println("obj2:", obj2.Field) 
}

Output: obj1: value1 obj2: value2

this does make sense
like over here we are trying to handle different field names and mapping them

[yendelevium]

Yeah, looks good to me @raamsri . How did u think of this lol i could never (like actually i wanna know your thought proccess)

[raamsri]

Nothing impressive but just a history with few years of sub-optimal design choices in the past 😅

Go's JSON package doesn't support multiple struct tags for the same field. And, I wince at the thought of maintaining new structs for every provider, so, I preferred a lazy solution as always. I've grudgingly applied similar logic for other projects where I had to transform(prefix, suffix, etc.) data before unmarshalling.

Though it may seem clean, I'm not quite content with the solution. At the worst case, extra JSON tags along with its mapping checks, grow linearly proportional to the total number of fields as new providers are added. So, I was honestly worried that you guys may not be happy with it. However, I do not have a better alternative.

[yendelevium]

@raamsri @adofm has any one started with this? If not i would like to take this up

[JrGkOG]

Yea I am working on this

[raamsri]

It would be great to try out pair programming for this one, if you hadn't done it before. Do you both fancy it?

[raamsri]

Nonetheless, @yendelevium there's more work on the plate. We haven't yet designed a way to orchestrate calls over the available meteo providers to fulfill the BaseData. There's a series of questions which we haven't sifted through yet. It may have to handle provider precedence as well when multi providers provide data for the same parameter, For instance, humidity is returned by both OM and MB, which one do we retain? In which order do we call? Does the order matter? When some of the fields couldn't be fulfilled for whatever reasons, should that be signaled separately for quick check without having to iterate the fields? If so then, what would be an efficient way to do that? And such things. It needs a new issue.