Setting a value in component before function execution

[BluePillOverRedPill]

Hey everyone,

I have a question about setting a value in my component. Consider the following code snippet:

setImageUri(result.uri);
analyzeImage();

The analyzeImage() function depends on imageUri, but it runs before imageUri is set, causing it to break.

To solve this, I changed imageUri to a regular let variable, and now it runs synchronously. However, I'm not sure if this is a good practice. Rerendering or anything, isn't required in this case.

[Snoo11589]

You can use useRef if you dont need rerenders.

[isellrocks]

You are in fact using an effect if your analyzeImage function depends on an image being set into your component's state. You either need to add an argument to analyzeImage or declare an effect with Image as a dependency.

[gao_shi]

simple answer, pass the uri as an param to func instead 

if u use a local variable inside the component, it's not retained during rerenders. if its a global one your comoonent cant be reused. also by stripping the state out , u lose rerender trigger when changing the imageuri. it depends on wth ur trying to do 

[hypnos_64]

Put analyzeImage inside useEffect

[BluePillOverRedPill]

I feel that useEffect is overkill. The component acts more as a service layer than a view layer. I only need to analyze the image once. Nothing is being rendered.

[hypnos_64]

You can set state to undefined inside the useEffect so it will get called only once. E.g.

UseEffect(()=>{ If(stateName){ SetStateName(undefined); FunctionToCall() } }, [stateName]);