Cannot set property 'order' of undefined

Greetings. I am seeing the following error:

TypeError: Cannot set property 'order' of undefined
    at dagre.core.js:1395
    at arrayEach (lodash.js:1289)
    at Function.<anonymous> (lodash.js:3345)
    at dagre.core.js:1394
    at arrayEach (lodash.js:1289)
    at Function.<anonymous> (lodash.js:3345)
    at assignOrder (dagre.core.js:1393)
    at order (dagre.core.js:1371)
    at dagre.core.js:495
    at notime (dagre.core.js:2897)

After doing some debugging I see the following:

function assignOrder(g, layering) {
  _.each(layering, function(layer) {
    _.each(layer, function(v, i) {
        g.node(v).order = i;
    });
  });
}

In this function layer is an array, seemingly containing strings (maybe id’s). When this error crops up, it seems that several items in the layer array are undefined. Therefore g.node(undefined) also returns undefined and produces the error.

I am currently going through our code to see what might be causing the issue, but was hoping that maybe the authors had some insight into what I might look for.

[josejulio]

@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

[gordonwoodhull]

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