Line not drawn in Line chart with react-chartjs-2

Question

I try to draw multi line chart (single line doesn't work as well) using react-chartjs-2 Line component

My data structure

const data = {
    labels: dataFromDb.map(item => item.period),
    datasets: [
        {
            data: dataFromDb,
            backgroundColor: '#FAA46A',
            borderColor: '#FAA46A',
            label: i18n.sellPrice,
            parsing: { yAxisKey: 'price_so' },
        },
        {
            data: dataFromDb,
            backgroundColor: '#1DCF35',
            borderColor: '#1DCF35',
            label: i18n.purchasePrice,
            parsing: { yAxisKey: 'price_po' },
        },
    ],
};

Data from db is array of objects {period: string, price_so: number, price_po: number, quantity: number}

My chart

<Line
    height={400}
    data={data}
    options={{
        animation: false,
        maintainAspectRatio: false,
        elements: { line: { tension: 0.4 } },
        scales: {
            x: { grid: { display: false }, offset: true },
            y: {
                title: { text: i18n.amount, display: true },
                grid: { display: false },
            },
        },
    }}
/>

Result

Problem is that none of the lines Visible. I can see that data is read as y axis have values mapped by object properties price_so and price_po (900 is highest value for price_po in objects array from db) and legend recognized datasets as correct colors applied but lines not draw. Am I missing something in configuration?

score 1 · Accepted Answer · answered Apr 15 '23 at 05:22

You should also set xAxisKey in parsing. It seems logical that the library would use period since you defined the labels as such, but apparently it doesn't make that infferrence by itself.

Here's a non-react example based on your code, with invented data:

const dataFromDb = [
    {period: '2019', price_so: 100, price_po: 110},
    {period: '2020', price_so: 120, price_po: 120},
    {period: '2021', price_so: 110, price_po: 109},
    {period: '2022', price_so: 90, price_po: 100},
    {period: '2023', price_so: 105, price_po: 115},
];
const data = {
    labels: dataFromDb.map(item => item.period),
    datasets: [
        {
            data: dataFromDb,
            backgroundColor: '#FAA46A',
            borderColor: '#FAA46A',
            label: 'sellPrice',
            parsing: { xAxisKey: 'period', yAxisKey: 'price_so' },
        },
        {
            data: dataFromDb,
            backgroundColor: '#1DCF35',
            borderColor: '#1DCF35',
            label: 'purchasePrice',
            parsing: { xAxisKey: 'period', yAxisKey: 'price_po' },
        },
    ],
};

const options={
    animation: false,
    maintainAspectRatio: false,
    /*elements: { line: { tension: 0.4 } },*/
    scales: {
        x: { grid: { display: false }, offset: true },
        y: {
            title: { text: 'amount', display: true },
            grid: { display: false },
        },
    },
};

new Chart(document.querySelector('#line-chart'), {type:'line', data, options});

<div id="line-chart-container">
<canvas id="line-chart"></canvas>
</div>

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/4.1.2/chart.umd.js"
        integrity="sha512-t41WshQCxr9T3SWH3DBZoDnAT9gfVLtQS+NKO60fdAwScoB37rXtdxT/oKe986G0BFnP4mtGzXxuYpHrMoMJLA=="
        crossorigin="anonymous" referrerpolicy="no-referrer">
</script>

Line not drawn in Line chart with react-chartjs-2

1 Answers1