react-dnd-drag-source.js

import {DragSource, DragDropContext, DropTarget, DragLayer} from 'react-dnd';

@connect((state, ownProps) => {
    let subjectsModule = state.subjectsModule,
        //...

    return {
        //........
    }
}, {...actionCreators})
@DragSource('subject', {
    beginDrag: props => {
        props.beginDrag(props.subject._id);
        return props.subject;
    },
    endDrag: props => {
        props.clearSubjectDragging();
    }
}, (connect, monitor) => ({
    connectDragSource: connect.dragSource(),
    connectDragPreview: connect.dragPreview()
}))
class SubjectDisplayContent extends Component {