Develop Reference

Gojs - MiniMap ( Reactoverview is not getting loaded) , But nodes get loaded

I was integrating gojs with react and was successfully able to integrated the nodes array and links array and was able to see the nodes in my page.
But the toughest thing , integrated ReactOverview (minimap) but i can see only small rectangle box on the page with no diagram in it.
Will share my code here
import PropTypes from 'prop-types';
import { connect } from 'react-redux';
import { ReactDiagram, ReactOverview } from 'gojs-react';
import * as go from 'gojs';
class DiagramContainer extends React.Component {
diagramRef;
static propTypes = {
diagramData: PropTypes.object.isRequired,
};
constructor(props) {
super(props);
this.diagramRef = React.createRef();
this.state = {};
}
initDiagram = () => {
const $ = go.GraphObject.make;
const diagram = $(go.Diagram, {
'undoManager.isEnabled': true,
'animationManager.isEnabled': false,
// 'undoManager.maxHistoryLength': 0,
model: $(go.GraphLinksModel, {
linkKeyProperty: 'key',
linkFromPortIdProperty: 'fromPort',
linkToPortIdProperty: 'toPort',
}),
});
const defaulttemplate = $(
go.Node,
'Vertical',
$(
go.Panel,
'Auto',
$(
go.Shape,
'hexagon',
{
width: 160,
height: 160,
},
),
$(
go.TextBlock,
}
)
);
var templateMap = new go.Map();
templateMap.add('normal', defaulttemplate);
//dummy codes
},
})
);
return diagram;
};
initDiagramOverview = () => {
const $ = go.GraphObject.make;
const overview = $(go.Overview, { contentAlignment: go.Spot.Center });
return overview;
};
render() {
const { diagramData } = this.props;
return (
<>
<div style={{ height: '100%' }}>
<ReactDiagram
ref={this.diagramRef}
divClassName='diagram-main'
id='diagram'
initDiagram={this.initDiagram}
flowDiagramData={diagramData}
nodeDataArray={diagramData.dataArray}
linkDataArray={diagramData.linksArray}
skipsDiagramUpdate={diagramData.skipsDiagramUpdate}
modelData={}
/>
</div>
<ReactOverview
initOverview={this.initDiagramOverview}
divClassName='diagram-observed'
observedDiagram={this.diagramRef.current?.getDiagram() || null}
/>
</>
);
}
}
export default DiagramContainer
```
But am not seeing mini map , i can just see a rectangle box instead of minimap. Still i cross checked with various things and am not sure what went wrong
Can you guys help me to resolve this issue

The problem is that your component only renders once for the given props (any interactive diagram changes are handled internally by GoJS and React is oblivious to that). When it renders the first and only time, this.diagramRef.current is still null. You can see this if you log it in the render method.
You need to use state to keep the "observed diagram" for the overview. Then when the overview component initializes, the diagram should be all set up and you can set the new state to cause re-render:
Add the state with the value of the diagram you want to observe in the overview:
constructor(props) {
super(props);
this.state = {
observedDiagram: null
};
this.diagramRef = React.createRef();
}
Use this state in the ReactOverview component:
<ReactOverview
initOverview={this.initDiagramOverview}
divClassName="diagram-overview-component"
observedDiagram={this.state.observedDiagram}
/>
Set the state when initializing the overview component:
initDiagramOverview = () => {
this.setState({
observedDiagram: this.diagramRef.current?.getDiagram() || null
});
const $ = go.GraphObject.make;
const overview = $(go.Overview, { contentAlignment: go.Spot.Center });
return overview;
};
You can see how it works in this sandbox

ReactJS and Google Maps - Displaying Markers

I'm React newbie so maybe asking a stupid question, but this has got me perplexed. As part of my learning I'm building a three component application - a parent About, and two children (GoogleMap and MapMarkerDetails). The parent does the data coordination and one child shows a google map with two markers as default, the other child shows details of the markers when it is clicked.
I am now adding functionality to add a new marker when the map is clicked. Most of the functionality works - the maps is draw, the default markers are added, and when one of the markers is clicked, this calls a function on the parent class which updates its state and this is propagated to the MapMarkerDetails element and a simple message is displayed.
Here is the parent class which I have commented to help understanding:
import React, { Component } from 'react';
import GoogleMap from './GoogleMap'
import MapMarkerDetails from './MapMarkerDetails'
class About extends Component {
state = {
markers: [{
position: { lat: 51.438759, lng: -2.864514 },
label: 'A',
map: null,
}, {
position: { lat: 51.433636, lng: -2.868734 },
label: 'B',
map: null,
}],
greeting: 'HelloA'
}
showMarkerInfo = (label) => {
this.setState({greeting: ('Hello ' + label)})
}
/*
Adding a new Marker
This function is called from the child element GoogleMap
However, the setState(...) dosn't seem to propogate down to the GoogleMap element.
*/
addMarker = (latlng) => {
let newMarker = [{
position: { lat: latlng.lat(), lng: latlng.lng() },
label: 'New',
map: null,
}];
/* Creates a new array for updating state. Is this the best way to do this */
let markers = [...this.state.markers, ...newMarker]
this.setState({markers});
console.log(this.state) // This shows the added marker
}
render() {
return (
<div className="container">
<h4 className="center">About</h4>
<MapMarkerDetails details={this.state.greeting}/>
<GoogleMap markers={this.state.markers} clickedMarker={this.showMarkerInfo} addMarker={this.addMarker}/>
</div>
)
}
}
export default About;
Here is the class that displays Google Map and the markers:
import React, { Component } from 'react';
class GoogleMap extends Component {
constructor(props) {
super(props);
this.googleMapRef = React.createRef(); // Create a referance for Google Map to draw to
console.log('Constructore')
}
componentDidMount(){
console.log('componentDidMount')
/* Create the Map */
let googleMap = new window.google.maps.Map(this.googleMapRef.current, {
zoom: 15,
center: {
lat: 51.436411,
lng: -2.861980,
},
disableDefaultUI: true,
})
this.placeMMarkers(googleMap) // Place the markers
this.addMapListner(googleMap) // Define a click listener to place new markers
}
/* Place the markers */
placeMMarkers = (googleMap) => {
this.props.markers.forEach((m) => {
m.map = googleMap;
let marker= new window.google.maps.Marker(m)
marker.addListener('click', () => { this.props.clickedMarker(m.label); });
}
);
}
/* Map listeners */
addMapListner = (googleMap) => {
googleMap.addListener('click', (e) => {
this.props.addMarker(e.latLng)
})
}
render() {
console.log('render: ' + this.props.markers) // This is showing the added markers
return (
<div
id="google-map"
ref={this.googleMapRef}
style={{ width: '800px', height: '400px', float: 'left' }}>
</div>
)
}
}
export default GoogleMap
I've added console logging to each function so I can follow what is happening.
Here is the MapMarkerDetails which displays a simple message when an marker is clicked. This all works fine.
import React, { Component } from 'react';
class MapMarkerDetails extends Component {
render(){
return (
<div style={{width: '100px', height: '400px', backgroundColor: 'gray', float: 'left'}}>
{this.props.details}
</div>
)
}
}
export default MapMarkerDetails
Description of the Problem
When the user clicks on the map (not a marker) this invokes the function addMarker which is passed down from the parent About class (snippet below). In the addMarker function of About the lat/lng is passed in. This represents where the user clicked. This is converted into a marker data object, then a new array is created which contains the default markers and the new one. I'm not sure if my new array creation is done in the best way - if not let me know.
Once the new array is created, we update the components state with this.setState({markers}). I thought this would lead to a re-render() and an redrawing of the map with the added marker. But not.
addMarker = (latlng) => {
let newMarker = [{
position: { lat: latlng.lat(), lng: latlng.lng() },
label: 'New',
map: null,
}];
/* Creates a new array for updating state. Is this the best way to do this */
let markers = [...this.state.markers, ...newMarker]
this.setState({markers});
console.log(this.state) // This shows the added marker
}
Something happens that results in the render() function of GoogleMap being called, but only the original markers are shown. The data is passed down to the GoogleMap component because I can see the output of console.log('render: ' + this.props.markers). But how do I get ALL the markers to load?
Please advise on what is the best way to for About to pass data to GoogleMap such that it can add in the new marker.

Just like you use componentDidMount to imperatively add the markers when the map is first loaded, you should use componentDidUpdate to do the same thing when the props change. In your GoogleMap component:
componentDidUpdate() {
this.placeMMarkers()
}
Rather than passing googleMap as an argument, I would set it as an instance variable in componentDidMount:
this.googleMap = new window.google.maps.Map(...
and then change placeMMarkers to use this.googleMap:
placeMMarkers = () => {
this.props.markers.forEach((m) => {
m.map = this.googleMap;
// ...
Since you are attaching an event handler in placeMMarkers, you should also add some logic to distinguish between new markers and existing ones, to avoid adding multiple event handlers to existing markers.
In response to your question about how best to set the state, I think what you've got is fine but you don't need to put the new marker inside an array:
let newMarker = {
position: { lat: latlng.lat(), lng: latlng.lng() },
label: 'New',
map: null,
};
let markers = [...this.state.markers, newMarker]

Mapbox in React without Class Components

I am trying to use MapBox-GL with React. I am trying to avoid using a wrapper.
I have sucessfully created the map using Class Components, but want to transform it to only using functions to take advantage of hooks. Displaying the map in a function works great:
const map = () => {
new mapboxgl.Map({
container: 'mapContainer',
style: 'mapbox://styles/mapbox/light-v9',
center: [7.32, 60.44],
zoom: 6,
})
};
const Map = () => {
const style = {
position: 'absolute',
top: 0,
bottom: 0,
width: '100%',
height: '100vh'
};
useEffect(()=>{
map();
});
return (
<Row type="flex" gutter="50">
<Col xs={{ span: 18 }}>
<div style={style} id="mapContainer" />
</Col>
</Row>
);
}
However, I want to add controllers and do things with the map. I do this normally in ComponentDidMount().
I have tried adding map.addControl(geocoder); for example to the useEffect, as well as outside the Map function. I am only getting errors:
TypeError: map.addControl is not a function

A counterpart to componentDidMount is useEffect with zero inputs.
map.addControl(geocoder) assumes that map is an instance of Map while it's a function and it doesn't return a value.
It should be:
const getMap = () => {
return new mapboxgl.Map({ ... })
};
const Map = () => {
useEffect(()=>{
const map = getMap();
map.addControl(geocoder);
}, []);
...
};

React google maps re-render issue using onBoundsChanged

I've got a project i'm working on where I use react google maps, however I've run into an issue where when I get the onBoundsChanged event and set state in the callback, it goes into a permanent loop of re rendering. I can only assume somehow that when the component re-renders after I call setState, it sets a new bounds and that will then re-trigger the callback and setState again, in form of an infinitely recursive loop.
import React from 'react'
import { compose, withProps, withStateHandlers, withState, withHandlers } from "recompose";
import {
withScriptjs,
withGoogleMap,
GoogleMap,
Marker
} from"react-google-maps";
import HouseDetails from './house/HouseDetails'
const { InfoBox } = require("react-google-maps/lib/components/addons/InfoBox");
class Map extends React.Component{
constructor(props){
super(props)
this.state = {
zoom: 15,
bounds: null
}
this.map = React.createRef()
this.onBoundsChanged = this.onBoundsChanged.bind(this)
this.onZoomChanged = this.onBoundsChanged.bind(this)
}
componentWillReceiveProps(test){
}
onBoundsChanged(){
this.setState({bounds: this.map.current.getBounds()}, ()=> console.log('update'))
let bounds = this.map.current.getBounds()
let realBounds = {lat:{west: bounds.ga.j, east: bounds.ga.l}, lon: {north: bounds.ma.j, south: bounds.ma.l}}
console.log(realBounds)
}
onZoomChanged(){
this.setState({zoom: this.map.current.getZoom()})
}
componentDidUpdate(){
console.log('hm')
}
render(){
return (
<GoogleMap
defaultZoom={15}
ref={this.map}
onZoomChanged={this.onZoomChanged}
onBoundsChanged={this.onBoundsChanged}
center={{ lat: 21.493468, lng: -3.177552}}
defaultCenter={this.props.center}>
</GoogleMap>
)
}
}
export default withScriptjs(withGoogleMap(Map))
The code for the component that re-renders to infinity is above, it doesn't bug out so as long as I don't setState in the onBoundsChanged function. Is there any way around this?

I am using react-google-maps.
if you want to update the marker on new position while dragging the map, you can use onBoundsChanged props
<GoogleMap
ref={refMap}
defaultZoom={13}
defaultCenter={{ lat: center.lat, lng: center.lng }}
onBoundsChanged={handleBoundsChanged}
fullscreenControl={false}
defaultOptions={defaultMapOptions}
onDragEnd={handleDragend}
>
<Marker position={center} />
</GoogleMap>
and in your handleBoundsChanged, you can update the center with new lat/lng
const handleBoundsChanged = () => {
console.log("handleBoundsChanged")
const lat = refMap.current.getCenter().lat()
const lng = refMap.current.getCenter().lng()
const mapCenter = {
lat: lat,
lng: lng,
}
setCenter(mapCenter); // move the marker to new location
};
if you want to move the map to new lat/lng programatically, you can use panTo function in useEffect when the address is updated. This is needed when you input the address in search and you want your map and marker at new location
//on address update
useEffect(() =>{
console.log("props updates", props.address, props.locationName)
if(props.address.source == 'searchbar'){
console.log("in the searchbar props")
const mapCenter = {
lat: props.address.latitude,
lng: props.address.longitude,
}
refMap.current.panTo(mapCenter) //move the map to new location
setCenter(mapCenter) // move the marker to new location
}
},[props.address])

I converted the class above from the docs compose examples, I must have screwed up somewhere because my mistake was very obvious, since on render the center is set for the GoogleMap object, all I had to do was have an initial state with a location, set the default state and then remove the 'center' prop from the component, this means that on re-render it does not pull it back to the center, and therefore does not re-trigger onBoundsChanged

Using Google Map API inside a React component

I am struggling over the way to use Google Map API inside a React component. I did not want to use popular react-google-maps nor google-map-react packages, but rather create my own.
I managed to load the script tag with the Google Map API from the React component. However, how do I manipulate the Google API from here? For example, initializing the map with even basic configuration like below?
map = new google.maps.Map(document.getElementById('map'), {
center: {lat: -34.397, lng: 150.644},
zoom: 8
});
Here is my component. Any advice is appreciated! thanks!
import React, { Component } from 'react';
// Load Google API in script tag and append
function loadScript(src) {
return new Promise((resolve, reject) => {
let script = document.createElement('script');
script.src = src;
script.addEventListener('load', function() {
resolve();
});
script.addEventListener('error', function(e) {
reject(e);
});
document.body.appendChild(script);
});
}
const script = 'https://maps.googleapis.com/maps/api/js?key=MY_API_KEY';
class MyGoogleMap extends Component {
constructor(props) {
super(props);
this.state = {};
}
componentDidMount() {
// first load the script into html
loadScript(script).then(function() {
console.log('SUCCESS');
// Where do I go from here?
});
}
render() {
return <div />;
}
}
export default MyGoogleMap;

I actually found my own solution, so I am sharing for anyone who would meet the same problem.
The basic logic is to use window object to access google.
So, after I load the script as I did from the question, I initialize my map as:
initMap = () => {
// 'google' could be accessed from 'window' object
const map = new window.google.maps.Map(
document.getElementById('googleMap'),
{
zoom: 14,
center: { lat: LATITUDE, lng: LONGTITUDE }
}
);
// putting a marker on it
const marker = new window.google.maps.Marker({
position: { lat: LATITUDE, lng: LONGTITUDE },
map: map
});
};
render() {
return (
<div id="googleMap" style={width: WIDTH, height: HEIGHT}/>
);
}
Any comment is welcomed :)

Create GoogleMap component with ref, to display google map inside that div.
import React, { Component } from 'react';
class GoogleMap extends Component {
componentDidMount() {
new google.maps.Map(this.refs.map, {
zoom: 12,
center: {
lat: this.props.lat,
lng: this.props.lon
}
});
}
render() {
return <div className="google-map" ref="map" />
}
}
export default GoogleMap;
Use it in Component you like like this:
<GoogleMap lat={lat} lon={lon}/>
by passing latitude and longitude of a city. To be able to see it you need to set width and height of css class google-map (or whatever you name it). for example:
div.google-map {
height: 150px;
width: 250px;
}
Fiddle.js preview
EDIT
inside head load script:
<script src="https://maps.googleapis.com/maps/api/js"></script>
I tought you have done that, because in your code you also use new google.maps.... If you cant call it like just google, try new window.google.maps...