vue and d3 force layout, network visualization - d3.js

Question

So I'm new to d3 and very little experimented with vue.
What I want to do is graph the network after the data has been fetched in a vue component.
I tried to recreate some of the older codes about vue and d3 force layout, and tried to adapt this example, but none of them worked out and I don't really know why.
The closest I got to what I want is probably this answer, but I want it to graph after the data has been fetched.
My code looks like this right now :
<script>
import * as d3 from "d3";
export default {
name: "MapComponent",
data() {
return {
mapData: {}
};
},
created() {
this.mapdataget();
},
computed() {
this.data_vis();
},
methods: {
mapdataget: function () {
this.$store
.dispatch("mapData_get")
.then(() => {
this.mapData = this.$store.getters.mapData;
})
.catch();
},
data_vis() {
let nodes = this.mapData.nodes;
let links = this.mapData.links;
let svg = d3.select("svg")
this.simulation = d3.forceSimulation()
.force("link", d3.forceLink().id(function (d) {
return d.id;
}))
.force("charge", d3.forceManyBody())
let link = svg.append("g")
.attr("class", "links")
.selectAll("line")
.data(links) //graph.links)
.enter().append("line")
.attr("stroke-width", function (d) {
return Math.sqrt(d.value);
});
let node = svg.append("g")
.attr("class", "nodes")
.selectAll("circle")
.data(nodes) //graph.nodes)
.enter().append("circle")
.attr("r", 5)
.call(d3.drag()
.on("start", this.dragstarted)
.on("drag", this.dragged)
.on("end", this.dragended));
node.append("title")
.text(function (d) {
return d.id;
});
this.simulation
.nodes(nodes)
.on("tick", ticked);
this.simulation.force("link")
.links(links); //graph.links);
function ticked() {
link
.attr("x1", function (d) {
return d.source.x;
})
.attr("y1", function (d) {
return d.source.y;
})
.attr("x2", function (d) {
return d.target.x;
})
.attr("y2", function (d) {
return d.target.y;
});
node
.attr("cx", function (d) {
return d.x;
})
.attr("cy", function (d) {
return d.y;
});
}
}
}
}
</script>
with mapData looking like this :
const mapData = {
'nodes': [{
'id':String
}, and more],
'links': [{
'id':String,
'source': sourceNodeId,
'target': targetNodeId
}, and more]
}
and the vue template is an svg :
<template>
<svg class='svg'></svg>
</template>
And I got an error :
[Vue warn]: Invalid value for option "computed": expected an Object,
but got Function.

Answer 1

In computed() you define variables that update the DOM at runtime, calling a method there without assigning a returned value or object to a variable is wrong. You should try moving this.data_vis() into the mounted() hook instead.