CODEWITHSUNDEEP
c#expression
SexyMF
SexyMF

Reputation: 11165

C# expression - extract the string name (Deep)

I have the function bellow, returning "Test" when I call it GetPropertyName<Model>(x => x.Test).
How can I return deep call eg: User.UserName.
I want to see User.UserName when I call it GetPropertyName<Model>(x => x.User.FullName)

Thanks

public static string GetPropertyName<T>(Expression<Func<T, object>> expression)
{
    var body = expression.Body as MemberExpression;
    if (body == null)
    {
        body = ((UnaryExpression)expression.Body).Operand as MemberExpression;
    }
    if (body != null)
    {
        return body.Member.Name;
    }
    return null;
}

Edit 1

this is my classes:

public class Place : BaseEntity
{
     public virtual User UserManager { get; set; }
}

public class User : BaseEntity
{
     public virtual string FullName { get; set; }
}

Upvotes: 0

Views: 268

Answers (1)

dcastro
dcastro

Reputation: 68670

This method loops through the nodes in the expression, casts the node to a property and adds it to a list.

private IList<PropertyInfo> GetProperties<T>(Expression<Func<T, object>> fullExpression)
{
    Expression expression;
    switch (fullExpression.Body.NodeType)
    {
        case ExpressionType.Convert:
        case ExpressionType.ConvertChecked:
            var ue = fullExpression.Body as UnaryExpression;
            expression = ((ue != null) ? ue.Operand : null) as MemberExpression;
            break;
        default:
            expression = fullExpression.Body as MemberExpression;
            break;
    }

    var props = new List<PropertyInfo>();

    while(expression != null && expression.NodeType == ExpressionType.MemberAccess)
    {
        var memberExp = expression as MemberExpression;

        if(memberExp.Member is FieldInfo)
            throw InvalidExpressionException.FieldFound;

        var prop = memberExp.Member as PropertyInfo;
        props.Insert(0, prop);

        expression = memberExp.Expression;
    }
    return props;
}

If you then want to get a string like this: User.UserName, you can do it this way:

var props = GetProperties<Model>(m => m.User.Username);
var propNames = props.Select(p => p.Name);
string names = string.Join(".", propNames);

Upvotes: 2

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