dagre: Cannot set property 'order' of undefined

@mmacfadden thanks to your reproducer and some guesswork i think i found out the problem.

Let me explain, the problems seems to be related to the way lodash forEach works, the method util.buildLayerMatrix builds a matrix, but the orders assigned there (layering[rank][node.order] = v;) are not always consecutive, so it ends up with a matrix with “holes” between orders. forEach methods seems to iterate over these undefined values in the assignOrder and thus the reported exception.

See a reproducer of what i mean:

var _ = require("lodash");

var arr = [];
arr[0] = 0;
arr[1] = 1;
arr[4] = 4;
arr[5] = 5;

console.log(arr);

console.log('for var i in arr:');
for (var i in arr) {
    console.log(`arr[${i}] = ${arr[i]}`);
}

console.log('_forEach:');
_.forEach(arr, function(v, i) {
    console.log(`arr[${i}] = ${v}`);
});

This yields:

[ 0, 1, <2 empty items>, 4, 5 ]
for var i in arr:
  arr[0] = 0
  arr[1] = 1
  arr[4] = 4
  arr[5] = 5
_forEach:
  arr[0] = 0
  arr[1] = 1
  arr[2] = undefined
  arr[3] = undefined
  arr[4] = 4
  arr[5] = 5

@Revadike, it’s likely because this project has no maintainer, as announced in the README.

For people that come here later, at least in my case, I found the issue and it was a really easy fix. When I add a node, I track the host field associated with it and do grouping so that all nodes with the same host are grouped together.

    g.setNode(node.id, {label: getLabel(node, view_config["label_components"]),  node: node, style: nodeColor, labelStyle: nodeLabelStyle, shape: 'circle'});
    g.setNode(node.host, {label: node.host, clusterLabelPos: 'top', style: 'fill:#d3d7e8', node: null});
    g.setParent(node.id, node.host);

However, I was doing some dummy data and the host field was blank, i.e. "". For whatever reason, this caused that error. I go back and set the host field for my data to be a >0 length string, and everything is working again. Hopefully that’ll be enough to help somebody since it doesn’t seem like this library is every gonna be updated again 😦

I am also having this issue. I’m using react-create-app, so it’s not easy to adjust build settings per @xnt 's suggestion. Any word on a fix?

I’m using dagre 0.8.5

Thanks a bunch!

EDITS: grammar, included a version number