[英]Access a Class (dbcontext) Property Dynamically by Property Name
我有一个 OnPost 方法,专门用于更新名为 Status 的特定 object:
public async Task OnPostStatus()
{
Status ExistingRecord = await _context.Status.FirstOrDefaultAsync(m => m.Id == Status.Id);
if (ExistingRecord == null)
{
_context.Status.Add(Status);
} else
{
ExistingRecord.Description = Status.Description;
ExistingRecord.Hint = Status.Hint;
_context.Attach(ExistingRecord).State = EntityState.Modified;
}
await _context.SaveChangesAsync();
StatusMessage = "Saved!";
await OnGetAsync();
}
但我实际上对其他 4 个具有完全相同属性的对象执行了完全相同的 OnPost。 因此,我想通过将 object 的类型传入 OnPost 来使其更具动态性,如下所示:
public async Task OnPost(string objectName)
{
var objectName ExistingRecord = await _context.(objectName).FirstOrDefaultAsync(m => m.Id == (objectName).Id);
if (ExistingRecord == null)
{
_context.(objectName).Add((objectName));
} else
{
ExistingRecord.Description = (objectName).Description;
ExistingRecord.Hint = (objectName).Hint;
_context.Attach(ExistingRecord).State = EntityState.Modified;
}
await _context.SaveChangesAsync();
StatusMessage = "Saved!";
await OnGetAsync();
}
我不知道具体的语法!
由于这些类具有完全相同的字段,您可以创建a common class
作为基础 class 来存储字段。
在我的示例中,有三个表(tb1、tb2、tb3)和一个基础 class( tbBase
),基础 class 与数据库无关:
public class tbBase
{
public int Id { get; set; }
public string Description { get; set; }
public string Hint { get; set; }
}
public class tb1: tbBase
{
}
public class tb2 : tbBase
{
}
public class tb3 : tbBase
{
}
然后从视图上看,将tbBase class as the parameter
传递给post方法,以及需要修改a specific table type parameter
。
<form method="post">
Id:<input id="Id" type="text" name="Id" /><br/>
Description: <input id="Description" type="text" name="Description" /><br/>
Hint: <input id="Hint" type="text" name="Hint" /><br/>
table type:<input id="Text1" type="text" name="type" />
<input id="Button1" type="submit" value="button" />
</form>
在 PageModel 中,通过Dictionary
存储参数表类型和具体类型的键值对:
public async Task OnPost(tbBase table, string type)
{
Dictionary<string, Type> TableTypeDictionary = new Dictionary<string, Type>()
{
{ "tb1", typeof(tb1) },
{ "tb2", typeof(tb2) },
{ "tb3", typeof(tb3) }
};
dynamic obj = Activator.CreateInstance(TableTypeDictionary[type]);
for (int i = 0; i < obj.GetType().GetProperties().Length; i++)
{
obj.GetType().GetProperties()[i].SetValue(obj, table.GetType().GetProperty(obj.GetType().GetProperties()[i].Name).GetValue(table, null), null);
}
var ExistingRecord = _context.Find(TableTypeDictionary[type], obj.Id);
if (ExistingRecord == null)
{
obj.Id = 0;//ID is self growing, no need to customize settings
_context.Add(obj);
}
else
{
ExistingRecord.Description = table.Description;
ExistingRecord.Hint = table.Hint;
_context.Attach(ExistingRecord).State = EntityState.Modified;
}
await _context.SaveChangesAsync();
StatusMessage = "Saved!";
await OnGetAsync();
}
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