How to use foreign key with memberName and load dataSource from Url

[Nguyen Ngoc]

I'm creating a generic grid, but have a problem that the foreign key column cannot use memberName and load datasource from url.
Please help me, thanks.

[Mihaela]

Hi Nguyen,

At this point, the "ForeignKey" method supports only predicates. However, I have created a feature request with a vote on your behalf asking to implement a String overload:

https://feedback.telerik.com/aspnet-core-ui/1524863-foreignkey-method-with-string-overload

Feel free to let me know in case of any other queries.

 

Regards, Mihaela Progress Telerik

[Nguyen Ngoc]

Thank Mihaela!

[Nguyen Ngoc]

Hi Mihaela,

Thank Mihaela, I used the temporary way:

var expression = PropertyExtensions.CreateExpression<T>(col.Name);
colBuild = d.ForeignKey(expression, ds => ds.Read(r => r.Url(col.ForeignUrl)), "Id", "Name");

But it throws an error if I don't specify a specific data type. (Ex: Expression<Func<T, object>>)

public static Expression<Func<T, int?>> CreateExpression<T>(string propertyName)
{
    var arg = Expression.Parameter(typeof(T), "x");
    var property = Expression.Property(arg, propertyName);
    //return the property as object
    //var conv = Expression.Convert(property, typeof(object));
    return Expression.Lambda<Func<T, int?>>(property, new ParameterExpression[] { arg });
}

[Mihaela]

Here is an example of how to get a field's type ("Type" is the Model type and "memberName" is the name of the field):

internal static MemberInfo FindPropertyOrField(this Type type, string memberName)
{
    MemberInfo memberInfo = type.FindPropertyOrField(memberName, false);
    if (memberInfo == null)
    {
       memberInfo = type.FindPropertyOrField(memberName, true);
    }

    return memberInfo;
}

internal static MemberInfo FindPropertyOrField(this Type type, string memberName, bool staticAccess)
{
    BindingFlags flags = BindingFlags.Public | BindingFlags.DeclaredOnly |
        (staticAccess ? BindingFlags.Static : BindingFlags.Instance);
    foreach (Type t in type.SelfAndBaseTypes())
    {
        var members = t.GetProperties(flags)
            .OfType<MemberInfo>()
            .Concat(t.GetFields(flags).OfType<MemberInfo>())
            .Where(m => m.Name.IsCaseInsensitiveEqual(memberName)).ToArray();
        if (members.Length != 0) return members[0];
    }
    return null;
}

internal static IEnumerable<Type> SelfAndBaseTypes(this Type type)
{
    if (type.IsInterface())
    {
        List<Type> types = new List<Type>();
        AddInterface(types, type);
        return types;
    }
    return SelfAndBaseClasses(type);
}

internal static IEnumerable<Type> SelfAndBaseClasses(this Type type)
{
    while (type != null)
    {
        yield return type;
        type = type.GetTypeInfo().BaseType;
    }
}

static void AddInterface(List<Type> types, Type type)
{
    if (!types.Contains(type))
    {
        types.Add(type);
        foreach (Type t in type.GetInterfaces()) AddInterface(types, t);
    }
}