React-dnd: Custom Drag Layer Shows both HTML style and Custom Layer

Created on 16 May 2017 · 3Comments · Source: react-dnd/react-dnd

Hi there, I have an issue where my custom drag layer is rendering both with my custom and HTML defined style. At the same time I am being warned that "setState cannot be called during an update transition".

Here's my code:

import React from 'react';
import PropTypes from 'prop-types';
import { DragLayer } from 'react-dnd';

import ItemDragPreview from './ItemDragPreview';

const layerStyles = {
    position: 'fixed',
    pointerEvents: 'none',
    zIndex: 200000
};

function getItemStyles(props){
    const {initialOffset, currentOffset} = props;

     if (!initialOffset || !currentOffset) {
        return {
        display: 'none'
        };
    }

    let {x,y} = currentOffset;
    const transform = `translate(${x}px,${y}px)`;
    return{
        transform
    };
}

class CustomDragLayer extends React.Component{
    static propTypes = {
        item: PropTypes.object,
        itemType: PropTypes.string,
        initialOffset: PropTypes.shape({
            x: PropTypes.number.isRequired,
            y: PropTypes.number.isRequired
        }),
        currentOffset: PropTypes.shape({
            x: PropTypes.number.isRequired,
            y: PropTypes.number.isRequired
        }),
        isDragging: PropTypes.bool.isRequired,
    }

    renderItem(type,item){
        return (<ItemDragPreview ruleitem={item}/>);
    }

    render(){
        const {item,itemType,isDragging} = this.props;
        if(!isDragging){
            return null;
        }

        return (
            <div style={layerStyles}>
                <div style={getItemStyles(this.props)}>
                    {this.renderItem(itemType,item)}
                </div>
            </div>
        );
    }

}

let collect = monitor =>{
    return {
        item: monitor.getItem(),
        itemType: monitor.getItemType(),
        currentOffset: monitor.getSourceClientOffset(),
        initialOffset: monitor.getInitialSourceClientOffset(),
        isDragging: monitor.isDragging()
    };
}

export default DragLayer(collect)(CustomDragLayer);

Here's the warning:

Warning: setState(...): Cannot update during an existing state transition (such as within render or another component's constructor). Render methods should be a pure function of props and state; constructor side-effects are an anti-pattern, but can be moved to componentWillMount.

I'm wondering if this is an error on my end or on the end of the library.
Thanks!

Source

FutureProg

Most helpful comment

What does the code for ItemDragPreview look like? I ran into this problem when trying to render a DragSource component.

Make sure ItemDragPreview isnt also a DragSource. If you're managing state within ItemDragPreview, try disabling that too. Basically shave everything off EXCEPT the html/jsx within that component(s). Start with that clean slate, then add things back to it one by one.