Am confused as to why my graph isn't showing up in vega? - vega-lite

Question

My graph isn't plotting in vega despite no error that i can see? Confused as to why this seems to be the case. I don't quite understand what I would've done wrong for the graph to not appear on the page. This is a template that I downloaded
{
"$schema": "https://vega.github.io/schema/vega-lite/v5.json",
"title": {
"text": "My new Covid Chart",
"subtitle":"This is my new chart",
"subtitleFontStyle":"italic",
"subtitleFontSize":10,
"anchor": "start",
"color": "black"
},
"data": {
"url": "https://api.coronavirus.data.gov.uk/v2/data?areaType=overview&metric=newCasesBySpecimenDate&format=csv",
"format": {"type": "csv"}
},
"transform":[
{"filter": {
"field": "areaName",
"oneOf": ["Bristol, City of", "Bolton", "Glasgow City"]}
}
],
"height": 300,
"width": 310,
"mark": {"type": "line", "point": false},
"encoding": {
"x": {
"field": "date",
"type": "temporal",
"title": null,
"axis": {"grid": false}
},
"y": {
"field": "newCasesByPublishDateRollingRate",
"type": "quantitative",
"title": null,
"axis": {"grid": false}
},
"color": {
"field": "areaName",
"type": "nominal",
"scale": {"scheme": "set1"},
"title": "LEGEND TITLE",
"legend": {
"orient": "top-left",
"fillColor": "#FcFdFd"}
}
}
}

Answer 1

You had applied filter transform which was not satisfying the criteria and making the data empty. Also the newCasesByPublishDateRollingRate field for y-axis used was not present in your data, instead I tried the field newCasesBySpecimenDate which worked.
Adding the correct config below or refer the editor:
{
"$schema": "https://vega.github.io/schema/vega-lite/v5.json",
"title": {
"text": "My new Covid Chart",
"subtitle": "This is my new chart",
"subtitleFontStyle": "italic",
"subtitleFontSize": 10,
"anchor": "start",
"color": "black"
},
"data": {
"url": "https://api.coronavirus.data.gov.uk/v2/data?areaType=overview&metric=newCasesBySpecimenDate&format=csv",
"format": {"type": "csv"}
},
"height": 300,
"width": 310,
"mark": {"type": "line", "point": false},
"encoding": {
"x": {
"field": "date",
"type": "temporal",
"title": null,
"axis": {"grid": false}
},
"y": {
"field": "newCasesBySpecimenDate",
"type": "quantitative",
"title": null,
"axis": {"grid": false}
},
"color": {
"field": "areaName",
"type": "nominal",
"scale": {"scheme": "set1"},
"title": "LEGEND TITLE",
"legend": {"orient": "top-left", "fillColor": "#FcFdFd"}
}
}
}