引用Azure Analysis Service表格模型时触发C#异常：DataSourceType值异常

Hey there, sorry to hear you're stuck with this frustrating error while working with Azure Analysis Services Tabular Models. Let's break down what's happening and walk through actionable fixes.

First, let's recap your issue clearly:

When accessing db.Model in your code, you hit this error:
Message=The value '2' is unexpected for type 'DataSourceType'.
The call stack traces back to Microsoft.AnalysisServices.Tabular.ObjectFactory.CreateDataSourceFromRowset

What's causing this? #

This error almost always stems from a version mismatch between your client library (Microsoft.AnalysisServices.Tabular) and the Azure Analysis Services instance you're connecting to.

The DataSourceType enum in the client library defines valid values for different data source types. The value '2' corresponds to a data source type that your current library version doesn't recognize—this could be a newer type (like Azure Data Lake Storage Gen2, or a preview data source) added in a recent AS service update, but your client package is outdated and hasn't caught up.

Step-by-Step Fixes #

1. Upgrade your Microsoft.AnalysisServices.Tabular NuGet package

This is the most common and effective fix. Head to your project's NuGet package manager:

• Locate Microsoft.AnalysisServices.Tabular and related packages (like Microsoft.AnalysisServices.Core)
• Upgrade them to the latest stable version (or at least a version that matches your Azure AS instance's compatibility level—you can check your AS instance version in the Azure Portal under the "Overview" tab)

Older library versions lack enum values for newer data source types, so upgrading should resolve the unrecognized '2' value.

2. Pinpoint the problematic data source

If upgrading doesn't fix the issue right away, isolate which data source in your model is triggering the error. Add this debug code to inspect data sources before accessing db.Model:

var ssasDb = SSASConnection.Instance(Parent.Name).Databases.Find(Id);

try
{
    // Try accessing data sources directly first to narrow down the issue
    var dataSources = ssasDb.Model.DataSources;
    foreach (var ds in dataSources)
    {
        Console.WriteLine($"DataSource: {ds.Name}, Type ID: {(int)ds.Type}, Type Name: {ds.Type}");
    }
}
catch (Exception ex)
{
    // If accessing the full model fails, use reflection to get raw values
    var modelProperty = ssasDb.GetType().GetProperty("Model", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic);
    var rawModel = modelProperty?.GetValue(ssasDb);
    var dataSourcesProp = rawModel?.GetType().GetProperty("DataSources");
    var rawDataSources = dataSourcesProp?.GetValue(rawModel) as System.Collections.IEnumerable;
    
    if (rawDataSources != null)
    {
        foreach (var ds in rawDataSources)
        {
            var nameProp = ds.GetType().GetProperty("Name");
            var typeProp = ds.GetType().GetProperty("Type");
            Console.WriteLine($"DataSource Name: {nameProp?.GetValue(ds)}, Raw Type Value: {typeProp?.GetValue(ds)}");
        }
    }
    Console.WriteLine($"Error details: {ex.Message}");
}

This will show you exactly which data source has the Type value of 2. Once identified, check if that type is supported by your upgraded library, or if it's a preview type that needs special handling.

3. Verify data source compatibility

If the problematic data source is a newer or preview type (like a recently launched Azure service connector), you might need to:

• Wait for an updated Microsoft.AnalysisServices.Tabular package that supports this type
• Temporarily replace the data source with a supported alternative (e.g., switch from a preview ADLS Gen2 connector to the standard one) to unblock your code

Final Notes #

Azure AS regularly rolls out new data source capabilities, so keeping your client libraries in sync with the service version is critical to avoiding these enum mismatch errors. Since you mentioned not finding a fix in the related thread, upgrading the NuGet packages is the first and most impactful step to try.

内容的提问来源于stack exchange，提问作者Essien