Azure TableEntity-挂接到读/写操作

Question

背景

假设我有一个Azure表实体

class MyEntity : TableEntity
{
    public string LongString { get; set; }
    public bool IsCompressed { get; set; }
}

如果LongString>64KB(Azure属性限制(，我想保存压缩的LongString。为此，我有两个功能Compress(string)和Decompress(string)

目前，在每次插入之前，我都会检查LongString的长度，如果它>64KB，我会设置LongString = Compress(LongString)和IsCompressed = true。每次Azure get操作后情况正好相反。

我想在整个代码中隐藏压缩选项，并将压缩和解压缩自包含在MyEntity类中。

问题

在从azure表获取和设置实体之前和之后，是否有进行自定义操作的选项？类似。。。

class MyEntity : TableEntity
{
    public string LongString { get; set; }
    public string IsCompressed { get; set; }
    public override void BeforeInsert()
    {
        if (LongString.Length > 64KB)
        {
            LongString = Compress(LongString);
            IsCompressed = true;
        }
    }
    public override void AfterGet()
    {
        if (IsCompressed)
        {
            LongString = Decompress(LongString);
            IsCompressed = false;
        }
    }
}

Answer 1

一种可能性可能类似于以下代码：

public bool IsCompressed;
public string StoredString { get; set; }
private string longString;
[IgnoreProperty] 
public string LongString
{
    get
    {
        if (this.longString == null)
        {
            if (IsCompressed)
            {
                this.longString = DeCompress(StoredString);
            }
            else
            {
                this.longString = StoredString;
            }
        }
        return this.longString;
    }
    set
    {
        if (longString != value)
        {
            this.longString = value;
            if (this.longString.Length > 64KB)
            {
                IsCompressed = true;
                this.StoredString = Compress(this.longString);
            }
        }
    }
}

但问问自己，总是保存压缩字符串是否不是更容易。

Answer 2

找到了一个使用ReadEntity和WriteEntity函数的解决方案。

class MyEntity : TableEntity
{
    public string LongString { get; set; }
    public bool IsCompressed { get; set; }
    public override void ReadEntity(IDictionary<string, EntityProperty> properties, OperationContext operationContext)
    {
        base.ReadEntity(properties, operationContext);
        if (IsCompressed)
        {
            LongString = Decompress(LongString);
            IsCompressed = false;
        }
    }
    public override IDictionary<string, EntityProperty> WriteEntity(OperationContext operationContext)
    {
        if (LongString.Length > 64KB)
        {
            LongString = Compress(LongString);
            IsCompressed = true;
        }
        return base.WriteEntity(operationContext);
    }
}

Answer 3

您不需要任何复杂度，只需创建计算属性即可写入表存储。而且您也不需要多个属性。因此，不需要具有具有IgnoreProperty属性的第二个属性。我在文本编辑器中键入了以下内容，但这应该会给你一些想法。

private string longString;
public bool IsCompressed { get; set; }
public string LongString
{
    get
    {
        return IsCompressed ? DeCompress(longString) : longString;
    }
    set
    {
       if (String.IsNullOrWhiteSpace(value) || value.Length < 64KB)
       {
           IsCompressed = false;
           longString = value;
       }
       else (value.Length > 64KB)
       {
           IsCompressed = true;
           longString = Compress(value);
       }
    }
}