How do I address method in a Vue.js component from inside callback function?

Question

I simply do not understand why I can't address the method "virtDia" from inside a callback function (line 64 and 70).

[Vue warn]: Error in mounted hook: "TypeError: this.virtDia is not a function" found in

---> at resources/assets/js/components/VegBedEditor.vue

TypeError: "this.virtDia is not a function"

<script>
    
    // vorlage: https://dev.to/ignoreintuition/binding-data-to-charts-using-vue-components-and-d3-4i27
    import * as d3 from 'd3';
    
    export default {
        props: ['data','vegbed'], 
        data: function () {
            return {
            }
        },
        computed: {
            displaywidth: function() { return 600; },
            displayheight: function() { return this.displaywidth*(this.vegbed.length/this.vegbed.width); },
            margin: function() { return {top: 0, right: 0, bottom: 0, left: 0}; }
        },
        methods: {
            initalizeChart: function () {
                this.drawGardenBox();
            },

            virtDia: function (realDia) {
                return (this.displaywidth/this.vegbed.width)*realDia;
            },
            drawGardenBox: function () {
                this.gardenbox = d3.select('#vegbedcontainer').append('svg')
                        .attr("width", this.displaywidth + this.margin.left + this.margin.right)
                        .attr("height", this.displayheight + this.margin.top + this.margin.bottom)

                // hintergrund für deselect zeichen
                var bg = this.gardenbox.append("g")
                    .on("click", mouseclick); // unselect on background click

                bg.append("rect") 
                    .attr('class', 'bg')
                    .attr("x", this.margin.left)
                    .attr("y", this.margin.top)
                    .attr("width", this.displaywidth + this.margin.left + this.margin.right)
                    .attr("height", this.displayheight + this.margin.top + this.margin.bottom)

                function mouseclick(d) {
                    d3.selectAll(".selected").raise().classed("selected",false);     
                }         
            },
            refreshBed: function () {
                var gplant = this.gardenbox.selectAll("g")
                .data(this.data).enter().append("g")
                .attr("id", function(d){ return d.id; })
                .attr("transform", function(d){ return "translate("+d.x+","+d.y+")" })
                .on("click", mouseclick)
                .call(d3.drag()
                .on("start", dragstarted)
                .on("drag", dragged)
                .on("end", dragended))
        
//                function virtDia(realDia) {
//                    return (this.displaywidth/this.vegbed.width)*realDia;
//                }

                gplant.append("circle") // max size
                    .attr('class', 'plant')
                    .attr("cx", function(d) { return d.x; })
                    .attr("cy", function(d) { return d.y; })
                    .attr("r", function(d) { return this.virtDia(d.plant.adult_diameter); });

                gplant.append("circle") // min size
                    .attr('class', 'plant')
                    .attr("cx", function(d) { return d.x; })
                    .attr("cy", function(d) { return d.y; })
                    .attr("r", function(d) { return this.virtDia(d.plant.exposure_diameter); });


                gplant.append("image")
                    .attr('class', 'plant')
                    .attr("xlink:href", function(d) { return d.picref; })
                    .attr("x", function(d) { return d.x-(d.picsize/2); })
                    .attr("y", function(d) { return d.y-(d.picsize/2); })
                    .attr("width", function(d) { return d.picsize; })
                    .attr("height", function(d) { return d.picsize; });


                function mouseclick(d) {
                    d3.selectAll(".selected").raise().classed("selected",false);
                    d3.select(this).selectAll(".plant").raise().classed("selected", true);
                    d3.selectAll("#"+this.id).classed("selected", true);      
                }

                function dragstarted(d) {
                    d3.selectAll(".selected").raise().classed("selected",false);
                    d3.select(this).selectAll(".plant").raise().classed("selected", true);
                    d3.selectAll("#"+this.id).classed("selected", true);

                    d3.event.sourceEvent.stopPropagation();
                }

                function dragged(d) {
                    d3.select(this).attr("transform","translate("+(d.x = d3.event.x)+","+(d.y = d3.event.y)+")");
                }

                function dragended(d) {
                    //d3.select(this).classed("active", false);
                }

            }
        },


        // lifecycle events
        mounted: function () { // <-- lifecycle events
            console.log('VegBedEditor mounted.')
            this.initalizeChart();
            this.refreshBed();
        },
        // watch functions
        watch: { // <-- watch functions
            'data': {
                handler: function (val) {
                    this.refreshBed();
                },
                deep: true
            }
        },
        template: `<div id="vegbedcontainer"><!-- SVG goes here --></div>`
    }
</script>

Boussadjra Brahim · Accepted Answer · 2018-12-10T21:33:29.947

Assign this to a global variable like vm and call it inside that callback :

   let vm=this;//<---

   gplant.append("circle") // max size
                .attr('class', 'plant')
                .attr("cx", function(d) { return d.x; })
                .attr("cy", function(d) { return d.y; })
                .attr("r", function(d) { return vm.virtDia(d.plant.adult_diameter); 
     });

                   gplant.append("circle") // min size
                .attr('class', 'plant')
                .attr("cx", function(d) { return d.x; })
                .attr("cy", function(d) { return d.y; })
                .attr("r", function(d) { return vm.virtDia(d.plant.exposure_diameter); });

How do I address method in a Vue.js component from inside callback function?

1 Answers1