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Blazor dotnet wrapper library for ChartJs

The current release is compatible with the following ChartJs versions Release | ChartJs | Tests ---|---|--- >= 0.5.0 | 4.x | 4.5.1

Getting started

This library is using JavaScript isolation. JS isolation provides the following benefits:

• Imported JS no longer pollutes the global namespace.
• Consumers of a library and components aren't required to import the related JS.

Installation

dotnet add package pax.BlazorChartJs

Program.cs:

    builder.Services.AddChartJs(options =>
    {
        // default
        options.ChartJsLocation = "https://cdn.jsdelivr.net/npm/chart.js";
        options.ChartJsPluginDatalabelsLocation = "https://cdn.jsdelivr.net/npm/chartjs-plugin-datalabels@2";
    });

If you want to serve Chart.js locally, you can provide your own URLs:

    builder.Services.AddChartJs(options =>
    {
        var version = "4.5.1";
        options.ChartJsLocation = $"/_content/dsstats.weblib/js/chart.umd.min.js?v={version}";
        options.ChartJsPluginDatalabelsLocation = "/_content/dsstats.weblib/js/chartjs-plugin-datalabels.min.js";
    });

Usage

Sample Project pax.BlazorChartJs.samplelib with Sample Chart

@using pax.BlazorChartJs

<div class="btn-group">
    <button type="button" class="btn btn-primary" @onclick="Randomize">Randomize</button>
</div>
<div class="chart-container w-75">
    <ChartComponent @ref="chartComponent"
                    ChartJsConfig="chartJsConfig"
                    OnEventTriggered="ChartEventTriggered">
    </ChartComponent>
</div>

@code {
    ChartJsConfig chartJsConfig = null!;
    ChartComponent? chartComponent;
    private bool chartReady;

    protected override void OnInitialized()
    {
        chartJsConfig = new ChartJsConfig()
            {
                Type = ChartType.bar,
                Data = new ChartJsData()
                {
                    Labels = ["Jan", "Feb", "Mar"],
                    Datasets = new List<ChartJsDataset>()
                    {
                        new BarDataset()
                        {
                            Label = "Dataset 1",
                            Data = [ 1, 2, 3 ]
                        }
                    }
                }
            };
        base.OnInitialized();
    }

    private void ChartEventTriggered(ChartJsEvent chartJsEvent)
    {
        if (chartJsEvent is ChartJsInitEvent initEvent)
        {
            chartReady = true;
        }
    }

    private void Randomize()
    {
        if (!chartReady)
        {
            return;
        }

        List<ChartJsDataset> updateDatasets = [];
        
        foreach (var dataset in chartJsConfig.Data.Datasets)
        {
            if (dataset is BarDataset barDataset)
            {
                List<object> newData = new();
                foreach (var data in barDataset.Data)
                {
                    newData.Add(Random.Shared.Next(1, 10));
                }
                barDataset.Data = newData;
                updateDatasets.Add(dataset);
            }
        }
        chartJsConfig.UpdateDatasetsSmooth(updateDatasets);
    }
}

Update Chart

• To update the chart with the current ChartJsConfig call ChartJsConfig.ReinitializeChart()
• To update the chart with smooth animations there are several helper functions available, e.g.:
  • ChartJsConfig.SetLabels(...)
  • ChartJsConfig.AddData(...)
  • ChartJsConfig.AddDatasetSmooth(...)
  • ChartJsConfig.SetData(...)
• use ChartJsConfig.UpdateChartOptions() to update the chart options, only (e.g. StepSize)

Chart Events

Several chart events are available, by default only the Init event is fired. The others can be activated in the ChartJsConfig.Options Sample

• click
• hover
• leave
• progress
• complete
• resize

Supported Plugins

• chartjs-plugin-datalabels
• ArbitraryLines (YouTube)
• Custom Plugins Sample

ChartComponent

Several chart functions are available in the ChartComponent, e.g.:

• ChartComponent.ResizeChart(...)
• ChartComponent.GetChartImage(...)
• ChartComponent.ToggleDataVisibility(...)

Contributing

We really like people helping us with the project. Nevertheless, take your time to read our contributing guidelines here.

Changelog

<details open="open"><summary>v0.8.6</summary>

• Updated to .NET 10
• Full JavaScript generation from TypeScript
• Chart.js v4.5.1 test coverage
• Improved JSON serialization to be more AOT‑friendly

</details> <details><summary>v0.8.5</summary>

• Microsoft.AspNetCore.Components.Web v8.0.*
• ChartJs v4.4.5 tests
• Test/Sample projects update to dotnet v8.0.10

</details> <details><summary>v0.8.4</summary>

• Microsoft.AspNetCore.Components.Web v8.0.8
• ChartJs v4.4.4 tests

</details> <details><summary>v0.8.3</summary>

• Microsoft.AspNetCore.Components.Web v8.0.2
• Added ChartJsConfig.UpdateDatasetsSmooth updates the ChartJs dataset(s), instead of replacing.
• Added BlazorLegendBase that can be used for a ChartJs Html Legend - [Sample][https://ipax77.github.io/pax.BlazorChartJs/htmllegendchart]
• Added ChartComponent.GetLegendItems()
• Added ChartComponent.IsDatasetVisible(int datasetIndex)
• Added ChartComponent.SetDatasetPointsActive(int datasetIndex)
• BarDataset.BarPercentage changed from int? to double?
• Renamed Layout to ChartJsLayout (CA1724)
• IndexableOption now supports Collection Expressions e.g.

    BorderColor = ["rgba(255, 99, 132, 1)", "rgba(54, 162, 235, 1)"],
    BorderWidth = [1, 2]

• ChartJs v4.4.2 Tests
• Blazor App sample

</details> <details><summary>v0.8.2</summary>

• ChartJs v4.4.1 tests
• Catching (more) dispose exeptions when switching from SSR to CSR (rendermode auto - AggregateException, JSDisconnectedException)

</details> <details><summary>v0.8.1</summary>

• dotnet 8 Breaking Change
• Added missing pie/doughnut dataset options (Cutout, Radius, Animation)
• The IndexableOption now supports implicit operators, allowing a more concise syntax for initialization.

New Syntax:

BorderColor = new List<string>()
{
    "rgba(255, 99, 132, 1)",
    "rgba(54, 162, 235, 1)"
},
BorderWidth = 1

Old Syntax (still possible):

BorderColor = new IndexableOption<string>(new List<string>()
{
    "rgba(255, 99, 132, 1)",
    "rgba(54, 162, 235, 1)"
}),
BorderWidth = new IndexableOption<double>(1)

</details> <details><summary>v0.6.3</summary>

• Reverted Microsoft.TypeScript.MSBuild to v5.2.2 Microsoft.TypeScript.MSBuild v5.3.2 not working for Blazor projects (only working for wasm)

</details> <details><summary>v0.6.2</summary>

• Microsoft.AspNetCore.Components.Web upgrade to v6.0.25
• Added missing pie/doughnut dataset options (Cutout, Radius, Animation)
• The IndexableOption now supports implicit operators, allowing a more concise syntax for initialization.

New Syntax:

BorderColor = new List<string>()
{
    "rgba(255, 99, 132, 1)",
    "rgba(54, 162, 235, 1)"
},
BorderWidth = 1

Old Syntax (still possible):

BorderColor = new IndexableOption<string>(new List<string>()
{
    "rgba(255, 99, 132, 1)",
    "rgba(54, 162, 235, 1)"
}),
BorderWidth = new IndexableOption<double>(1)

</details> <details><summary>v0.6.1</summary>

• ChartJsLabelClickEvent and ChartJsLabelHoverEvent with 'nearest' DatasetLabel and DatasetIndex
• Microsoft.AspNetCore.Components.Web upgrade to v6.0.21

</details> <details><summary>v0.6.0</summary>

• Fix typo for AngleLines in LinearRadialAxis Breaking Change

</details> <details><summary>v0.5.2</summary>

• Datalabels per dataset contributed by pjvinson
• ChartJs v4.4.0 tests

</details> <details><summary>v0.5.1</summary>

• Marked ChartJsGrid border options as obsolete for v4.x - use ChartJsAxisBorder instead.
• TimeSeriesAxis Min, Max, SuggestedMin and SuggestedMax are of type StringOrDoubleValue, now.
• Microsoft.AspNetCore.Components.Web upgrade to v6.0.16
• ChartJs v4.3.0 tests
• ChartJs v4.3.1 tests
• ChartJs v4.3.3 tests

</details> <details><summary>v0.5.0</summary>

• Breaking Changes
• Update to ChartJs v4.x
• Removed ChartJs javascript files - defaults to cdn links, now. Use options.ChartJsLocation = "mychart.js" to use a custom/local ChartJs version.
• Removed chartjs-plugin-labels (you can still register it as custom plugin)
• Microsoft.AspNetCore.Components.Web upgrade to v6.0.13
• Added ScaleAxis X1 and Y1 (overrid