C# 将通用嵌套列表转换为Datatable

我一直在使用以下代码将泛型

列表

转换为

数据表

：

    public static DataTable ToDataTable<T>(this IList<T> data)
    {
        PropertyDescriptorCollection properties = 
            TypeDescriptor.GetProperties(typeof(T));
        DataTable table = new DataTable();
        foreach (PropertyDescriptor prop in properties)
            table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
        foreach (T item in data)
        {
            DataRow row = table.NewRow();
            foreach (PropertyDescriptor prop in properties)
                 row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
            table.Rows.Add(row);
        }
        return table;
    }

| GenericProperty | GenericNestedProperty |
|-----------------|-----------------------|
|      fooA       |         barA          |
|      fooA       |         barB          |

要生成

数据表

：

    public static DataTable ToDataTable<T>(this IList<T> data)
    {
        PropertyDescriptorCollection properties = 
            TypeDescriptor.GetProperties(typeof(T));
        DataTable table = new DataTable();
        foreach (PropertyDescriptor prop in properties)
            table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
        foreach (T item in data)
        {
            DataRow row = table.NewRow();
            foreach (PropertyDescriptor prop in properties)
                 row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
            table.Rows.Add(row);
        }
        return table;
    }

| GenericProperty | GenericNestedProperty |
|-----------------|-----------------------|
|      fooA       |         barA          |
|      fooA       |         barB          |

原始代码解释了

foo

中的许多属性，

bar

也有此要求

到目前为止，我已经能够检索到

bar

的属性，但是当

List

为空时，我无法找出如何填充

Datatable

。我没有很多编写泛型方法的经验，所以我很抱歉不能提供我的很多工作

其他示例：

名单

名单

课程：

foo

class foo
{
    public string GenericProperty;
    public List<bar> GenericNestedList;

    public foo(string GenericProperty, List<bar> GenericNestedList)
    {
        this.GenericProperty = GenericProperty;
        this.GenericNestedList = GenericNestedList;
    }
}

只是一个快速解决方案：

public DataTable CreateNestedDataTable<TOuter, TInner>(IEnumerable<TOuter> list, string innerListPropertyName)
{
    PropertyInfo[] outerProperties = typeof(TOuter).GetProperties().Where(pi => pi.Name != innerListPropertyName).ToArray();
    PropertyInfo[] innerProperties = typeof(TInner).GetProperties();
    MethodInfo innerListGetter = typeof(TOuter).GetProperty(innerListPropertyName).GetMethod;

    // set up columns
    DataTable table = new DataTable();
    foreach (PropertyInfo pi in outerProperties)
        table.Columns.Add(pi.Name, Nullable.GetUnderlyingType(pi.PropertyType) ?? pi.PropertyType);
    foreach (PropertyInfo pi in innerProperties)
        table.Columns.Add(pi.Name, Nullable.GetUnderlyingType(pi.PropertyType) ?? pi.PropertyType);

    // iterate through outer items
    foreach (TOuter outerItem in list)
    {
        var innerList = innerListGetter.Invoke(outerItem, null) as IEnumerable<TInner>;
        if (innerList == null || innerList.Count() == 0)
        {
            // outer item has no inner items
            DataRow row = table.NewRow();
            foreach (PropertyInfo pi in outerProperties)
                row[pi.Name] = pi.GetValue(outerItem) ?? DBNull.Value;
            table.Rows.Add(row);
        }
        else
        {
            // iterate through inner items
            foreach (object innerItem in innerList)
            {
                DataRow row = table.NewRow();
                foreach (PropertyInfo pi in outerProperties)
                    row[pi.Name] = pi.GetValue(outerItem) ?? DBNull.Value;
                foreach (PropertyInfo pi in innerProperties)
                    row[pi.Name] = pi.GetValue(innerItem) ?? DBNull.Value;
                table.Rows.Add(row);
            }
        }
    }

    return table;
}

---

嗨@poke，谢谢你的回复。上面的代码有两个问题：每个

行[pi.Name]=pi.GetValue（outerItem）？？DBNull.Value

正在生成错误“方法“GetValue”的无重载包含1个参数。

typeof（TOuter）.GetProperty（innerListPropertyName）.GetMethod；

也正在生成错误“'System.Reflection.PropertyInfo'不包含“GetMethod”的定义。。。“@Chawin您的目标.NET framework版本是什么？

PropertyInfo.GetValue

和

PropertyInfo.GetMethod

都是在.NET 4.5中引入的。真是不同寻常，我在Visual C#2010 express上运行了4.5.51209版。我会仔细研究一下，看看是什么导致了这个问题。@Chawin我已经添加了一些说明，说明了旧版本应该替换什么。我不知道为什么会这样，我当然不是故意的！标记回已接受：）

| GenericProperty | GenericNestedProperty |
|-----------------|-----------------------|
|      fooC       |         barC          |
|      fooC       |         barD          |
|      fooD       |         barE          |
|      fooD       |         barF          |

class foo
{
    public string GenericProperty;
    public List<bar> GenericNestedList;

    public foo(string GenericProperty, List<bar> GenericNestedList)
    {
        this.GenericProperty = GenericProperty;
        this.GenericNestedList = GenericNestedList;
    }
}

class bar
{
    public string GenericNestedProperty;

    public bar(string GenericNestedProperty)
    {
        this.GenericNestedProperty = GenericNestedProperty;
    }
}

public DataTable CreateNestedDataTable<TOuter, TInner>(IEnumerable<TOuter> list, string innerListPropertyName)
{
    PropertyInfo[] outerProperties = typeof(TOuter).GetProperties().Where(pi => pi.Name != innerListPropertyName).ToArray();
    PropertyInfo[] innerProperties = typeof(TInner).GetProperties();
    MethodInfo innerListGetter = typeof(TOuter).GetProperty(innerListPropertyName).GetMethod;

    // set up columns
    DataTable table = new DataTable();
    foreach (PropertyInfo pi in outerProperties)
        table.Columns.Add(pi.Name, Nullable.GetUnderlyingType(pi.PropertyType) ?? pi.PropertyType);
    foreach (PropertyInfo pi in innerProperties)
        table.Columns.Add(pi.Name, Nullable.GetUnderlyingType(pi.PropertyType) ?? pi.PropertyType);

    // iterate through outer items
    foreach (TOuter outerItem in list)
    {
        var innerList = innerListGetter.Invoke(outerItem, null) as IEnumerable<TInner>;
        if (innerList == null || innerList.Count() == 0)
        {
            // outer item has no inner items
            DataRow row = table.NewRow();
            foreach (PropertyInfo pi in outerProperties)
                row[pi.Name] = pi.GetValue(outerItem) ?? DBNull.Value;
            table.Rows.Add(row);
        }
        else
        {
            // iterate through inner items
            foreach (object innerItem in innerList)
            {
                DataRow row = table.NewRow();
                foreach (PropertyInfo pi in outerProperties)
                    row[pi.Name] = pi.GetValue(outerItem) ?? DBNull.Value;
                foreach (PropertyInfo pi in innerProperties)
                    row[pi.Name] = pi.GetValue(innerItem) ?? DBNull.Value;
                table.Rows.Add(row);
            }
        }
    }

    return table;
}

var table = CreateNestedDataTable<foo, bar>(GenericList, "GenericNestedList");

// before
typeof(TOuter).GetProperty(innerListPropertyName).GetMethod;

// after
typeof(TOuter).GetProperty(innerListPropertyName).GetGetMethod(true);


// for each row assignment
// before
row[pi.Name] = pi.GetValue(item) ?? DBNull.Value;

// after
row[pi.Name] = pi.GetValue(item, null) ?? DBNull.Value;