React Component for Gutenberg - Post Selector using `withSelect`

block.jsx

const { _x } = wp.i18n;

import editMask from './postSelector.jsx';

wp.blocks.registerBlockType( 'sht/clubgallery-teaser', {
	title: _x('Bildergalerie - Teaser', 'Block title', 'sha'),
	icon: 'format-gallery',
	category: 'sht/custom',
	supports: {
		align: [
			'wide', 'full'
		],
		anchor: true,
		html: false
	},
	attributes: {
		post: {
			type: 'string',
			default: ''
		}
	},

	edit: editMask,

	save() {
		return null;
	}
});

PostSelector.jsx

const { _x } = wp.i18n;
const { ServerSideRender, PanelBody, SelectControl } = wp.components;
const { select, withSelect } = wp.data;
const { InspectorControls } = wp.editor;
const { Component } = wp.element;

class PostSelector extends Component {

	constructor() {
		super( ...arguments );
	}

	setPost( post ) {
		const { setAttributes } = this.props;
		setAttributes( { post } );
	}

	/**
	 * Must return a single DOM node, hence the anonymous wrapper
	 */
	render() {

		const { attributes, name, selectOptions } = this.props;
		const { post } = attributes;

		return (<>
			<InspectorControls>
				<PanelBody title={_x( 'Block Options', 'Editor panel title', 'sha' )} initialOpen={true}>
					<SelectControl
						label={_x( 'Bildgalerie auswählen', 'Select field label', 'sha' )}
						value={post}
						options={selectOptions}
						onChange={this.setPost.bind( this )}
					/>
				</PanelBody>
			</InspectorControls>
			<ServerSideRender block={name} attributes={attributes}/>
		</> );
	}
}

export default withSelect( ( select, props ) => {

	const { getEntityRecords } = select( 'core' );
	const POST_TYPE = 'clubgallery';
	const POST_LIST_QUERY_PARAMS = {
		per_page: -1,
		orderby: 'title',
		order: 'asc'
	};

	let selectOptions = [{
		label: _x( 'Auswählen', 'Default selector label', 'sha' ),
		value: ''
	}];

	let posts = getEntityRecords( 'postType', POST_TYPE, POST_LIST_QUERY_PARAMS );

	if ( !posts ) {
		return posts;
	}

	posts.map( post => {
		selectOptions.push( { value: post.id, label: post.title.raw } );
	} );

	return {
		selectOptions: selectOptions
	};
} )( PostSelector );