从Microsoft.WindowsAzure.Storage.Table迁移到Azure.Data.Tables的反序列化问题

针对迁移后遇到的反序列化异常问题，有两种实用方案可以实现“反序列化失败时将属性设为null”的需求：

方案一：手动映射TableEntity（灵活可控） #

先将数据查询为原始的TableEntity类型（不会自动进行类型转换，避免崩溃），再手动将每个属性映射到自定义实体，过程中捕获转换异常并设为null。

var table = tableServiceClient.GetTableClient(CloudTableNames.Workstations);
// 查询原始TableEntity，跳过自动反序列化
var tableEntities = table.Query<TableEntity>(c => c.PartitionKey == customerId);
var workstations = new List<WorkstationInfoTableEntity>();

foreach (var entity in tableEntities)
{
    var workstation = new WorkstationInfoTableEntity
    {
        PartitionKey = entity.PartitionKey,
        RowKey = entity.RowKey,
        Timestamp = entity.Timestamp,
        ETag = entity.ETag
    };

    // 处理Documents属性：尝试Base64解码，失败则设为null
    if (entity.TryGetValue(nameof(WorkstationInfoTableEntity.Documents), out var docsValue) && docsValue is string docsStr)
    {
        try
        {
            workstation.Documents = Convert.FromBase64String(docsStr);
        }
        catch (FormatException)
        {
            workstation.Documents = null;
        }
    }

    // 处理DateTime?类型属性：尝试转换，空字符串或失败均设为null
    if (entity.TryGetValue(nameof(WorkstationInfoTableEntity.MyDocumentsLastRestoreDate), out var restoreDateValue) && restoreDateValue is string restoreDateStr)
    {
        workstation.MyDocumentsLastRestoreDate = DateTime.TryParse(restoreDateStr, out var date) ? date : null;
    }

    if (entity.TryGetValue(nameof(WorkstationInfoTableEntity.MyDocumentsModifiedOn), out var modifiedOnValue) && modifiedOnValue is string modifiedOnStr)
    {
        workstation.MyDocumentsModifiedOn = DateTime.TryParse(modifiedOnStr, out var date) ? date : null;
    }

    // 其他属性按相同逻辑处理
    workstations.Add(workstation);
}

var results = workstations.OrderBy(c => c.Name).ToArray();

方案二：继承TableEntity并重写ReadEntity（封装性好） #

让自定义实体继承TableEntity而非直接实现ITableEntity，重写ReadEntity方法来控制属性的转换逻辑，捕获异常并设置null值。

public class WorkstationInfoTableEntity : TableEntity
{
    public byte[] Documents { get; set; }
    public DateTime? MyDocumentsLastRestoreDate { get; set; }
    public DateTime? MyDocumentsModifiedOn { get; set; }    
    // 其他属性...

    public override void ReadEntity(IDictionary<string, EntityProperty> properties, OperationContext operationContext)
    {
        // 先处理PartitionKey、RowKey等基础属性
        base.ReadEntity(properties, operationContext);

        // 处理Documents属性
        if (properties.TryGetValue(nameof(Documents), out var docProp))
        {
            try
            {
                // 优先尝试读取二进制值，若为字符串则尝试Base64解码
                Documents = docProp.BinaryValue ?? Convert.FromBase64String(docProp.StringValue);
            }
            catch (FormatException)
            {
                Documents = null;
            }
        }

        // 处理MyDocumentsLastRestoreDate
        if (properties.TryGetValue(nameof(MyDocumentsLastRestoreDate), out var restoreProp))
        {
            try
            {
                MyDocumentsLastRestoreDate = restoreProp.DateTimeOffsetValue?.DateTime;
            }
            catch (FormatException)
            {
                MyDocumentsLastRestoreDate = null;
            }
            // 单独处理空字符串场景
            if (restoreProp.StringValue == string.Empty)
            {
                MyDocumentsLastRestoreDate = null;
            }
        }

        // 处理MyDocumentsModifiedOn
        if (properties.TryGetValue(nameof(MyDocumentsModifiedOn), out var modifiedProp))
        {
            try
            {
                MyDocumentsModifiedOn = modifiedProp.DateTimeOffsetValue?.DateTime;
            }
            catch (FormatException)
            {
                MyDocumentsModifiedOn = null;
            }
            if (modifiedProp.StringValue == string.Empty)
            {
                MyDocumentsModifiedOn = null;
            }
        }

        // 其他属性按相同逻辑处理
    }
}

使用时直接查询该实体类即可，重写的ReadEntity会自动处理异常：

var table = tableServiceClient.GetTableClient(CloudTableNames.Workstations);
var workstations = table.Query<WorkstationInfoTableEntity>(c => c.PartitionKey == customerId);
var results = workstations.OrderBy(c => c.Name).ToArray();

内容的提问来源于stack exchange，提问作者kseeker