[Maps] Provide ability to create MapEmbeddable directly from a map configuration

[nreese]

fixes #43834

Adds createFromState method to MapEmbeddableFactory so map embeddables can be created from javascript objects instead of requiring saved objects. This will be useful for applications like SIEM and APM that want to embed maps that are programmatically defined and do not need to be saved in .kibana index.

Usage

const state = {
  layerList: [],  // where layerList is same as saved object layerListJSON property (unstringified)
  title: 'panel title',
}
const input = {
  hideFilterActions: true,
  isLayerTOCOpen: false,
  openTOCDetails: [],
  mapCenter: { lat: 0.0, lon: 0.0, zoom: 7 }
}
factory.createFromState(state, input, parent);

cc @spong @ogupte

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Pinging @elastic/kibana-gis

[nreese]

@stacey-gammon

Why does abstract Embeddable constructor reset the this.input to parent.getInputForChild<TEmbeddableInput>(this.id)?

Why does the embeddable constructor even take initialInput as an argument if its going to overridden by the super constructor?

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[stacey-gammon]

We discussed offline but will summarize here for documentation.

Why does abstract Embeddable constructor reset the this.input to parent.getInputForChild(this.id)?

It's setting up a listener on the parent so that when the parent changes, this child's input changes too, so it gets any new inherited or explicit input variables.

Why does the embeddable constructor even take initialInput as an argument if it's going to overridden by the super constructor?

It only overwrites it if there is a parent, and will continue to update it when the parent changes.

There might be a better way to code this to make this easier to understand. Do something like, if there is a parent, then only get input from the parent, don't take it as a constructor argument. I'm slightly suspicious that reseting the input is actually the right thing to do vs updating only the input parameters given by the parent explicitly (e.g. resetInput vs updateInput). I know I had it as updateInput at some point but changed it. I should have commented on why. It probably had something to do with clearing variables out, so you can say something like "don't use an explicit time range on this panel anymore, I want to set this as undefined". Though thinking about it now, if you want to explicitly clear out a variable, you should just do { timeRange: undefined }.

How to fix it

The issue was that the updates coming from the container were overwriting the updating initially passed in from the constructor. One way to fix that is to call embeddable.updateInput(explicitInput) after the embeddable is created, which will save that input as explicitInput on the parent and it will not be overwritten anymore.

But like I said, there might be an issue here where we really should only be calling this.updateInput instead of this.resetInput.

cc @streamich

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[nreese]

retest

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[kindsun]

Best option for a near-term win. Nice work!

• code review
• tested locally in chrome

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