SolidJS•16mo ago

Reactivity when passing props down not reactive on nested component

Hi guys and girls, I'm currently struggling with reactivity. Here's a look at the code: ParentComponent.tsx

                  
export default function ParentComponent(props) {
  // signal stuff
  const [level, setLevel] = createSignal(...)
  // create effect stuff

  return level()?.placements.map((placement) => {
    const [x, y] = placement.displayXY()

    return (
        <div
            style={{
              position: 'absolute',
              transform: `translate3d(${x}px, ${y}px, 0px`,
            }
            }>
          {placement.renderComponent()}
        </div>
    )
  }
}

                  
export default function ParentComponent(props) {
  // signal stuff
  const [level, setLevel] = createSignal(...)
  // create effect stuff

  return level()?.placements.map((placement) => {
    const [x, y] = placement.displayXY()

    return (
        <div
            style={{
              position: 'absolute',
              transform: `translate3d(${x}px, ${y}px, 0px`,
            }
            }>
          {placement.renderComponent()}
        </div>
    )
  }
}

If I add this in the parent to test, everything works correctly and properties are reactive. However, when I move this into another component ChildComponent.tsx I loose reactivity and instead get static values... ParentComponent.tsx:

export default function ParentComponent(props) {
  // signal stuff
  const [level, setLevel] = createSignal(...)

  // create effect stuff

  return(
   <ChildComponent level={level()} />
  )
}

export default function ParentComponent(props) {
  // signal stuff
  const [level, setLevel] = createSignal(...)

  // create effect stuff

  return(
   <ChildComponent level={level()} />
  )
}

ChildComponent.tsx:

export default function ChildComponent(props) {
  return (
      <For each={props.level.placements}>
        {(placement) => {
          const [x, y] = placement.displayXY()

          return (
            <div
              style={{
                position: 'absolute',
                transform: `translate3d(${x}px, ${y}px, 0)`,
              }}
            >
              {placement.renderComponent()}
            </div>
          )
        }}
      </For>
  )
}

export default function ChildComponent(props) {
  return (
      <For each={props.level.placements}>
        {(placement) => {
          const [x, y] = placement.displayXY()

          return (
            <div
              style={{
                position: 'absolute',
                transform: `translate3d(${x}px, ${y}px, 0)`,
              }}
            >
              {placement.renderComponent()}
            </div>
          )
        }}
      </For>
  )
}

Any help would be greatly appreciated, thanks in advance!

10 Replies

foolswisdom•16mo ago

Quick sanity check - the code as two components and one component are me the same. Namely, one uses the map method, and the other uses For (and also doesn't use optional chaining, so level may be undefined?) Can you confirm that it behaves differently even when the two version are the same?

Casacobra•16mo ago

@foolswisdom If I do it in the root component, ParentComponent as a map it works and reactivity works, the minute i move it to a child component is when it does not become reactive when I use <For> or map... It's so strange..

foolswisdom•16mo ago

So, when you say that it's not reactive, does that mean the x and y properties don't update, or that nothing happens when you add items

Casacobra•16mo ago

@foolswisdom Exactly, x and y do not update for some bizarre reason But if i move the code to the root component, it's reactive, with the exception of using .map

foolswisdom•16mo ago

It looks like x and y aren't signals, ah the only way for them to update would be to rerun the whole block. Which would require the display method to access reactive values. So does it access signals / stores? (i don't know why this would have been working in a single component 🤷)

Casacobra•16mo ago

It accesses one signal called [level, setLevel] Please bare in mind, which I forgot to say. level is constantly looping as in using requestAnimationFrame...

high1•16mo ago

I think that you should just wrap the result in a function const placement = () => placement.displayXY() And then access it like placement().x and placement().y

Casacobra•16mo ago

Yeah I tried this too and for some bizarre reason it isn’t playing nicely! Thanks for the response. I’ll continue debugging and see where I get to!

REEEEE•16mo ago

You could perhaps use a store? It could be the values for level are updated maybe?

high1•16mo ago

The function approach should work. Solid is not detecting that something has changed, so you need to add a hint to make this reactive. Or you could use a store, which also must work.

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Reactivity when passing props down not reactive on nested component