如何检查是否已填充ViewModel的任何属性

Question

I have a ViewModel which contains properties that can optionally be filled from the user of my web application (eg first name, last name, e-mail, date of birth etc). These properties include several types like string, bool int, decimal, double, DateTime. All these types can be both nullable and non-nullable in the ViewModel.

If at least 1 of these properties has been filled in, then I have to create a database record. Do you have any idea for a way to check if any of these optional values has been filled?

Answer 1

By convention, primitive data types are required. You can make the properties nullable which are primitive like int, double, DateTime vs. Then:

PropertyInfo[] infos = yourObjectInstance.GetType().GetProperties();            
int count = 0;

for(int i = 0; i < infos.Length; i++)
{
    if(infos[i].PropertyType == typeof(string))
    {
        string stringValue = infos[i].GetValue(yourObjectInstance).ToString().Trim();

        if(!string.IsNullOrEmpty(body))
        {
            count++;
        }

        continue;
    }

    if(infos[i].GetValue(yourObjectInstance) != null)
    {                    
        count++;
    }
}

if(count == 0)
{
    // Handle error
}

// Create record

Answer 2

You can implement this code, pass your viewmodel, then count how much fields are not null, if the return value>0 , then you can implement your Db work.

public int MethodToCheckNotNull(ViewModel obj)
{
        int i = 0;
        PropertyInfo[] properties = typeof(obj).GetProperties();
        foreach (PropertyInfo property in properties)
        {
            if (property.GetValue(obj) != null)
            {
                i++;
            }
        }
        return i;
 }