Serialize Custom Attribute Values - c#-4.0

Question

Given the following class:
public class PayrollReport
{
[UiGridColumn(Name = "fullName",Visible = false,Width = "90")]
public string FullName { get; set; }
[UiGridColumn(Name = "weekStart", CellFilter = "date")]
public DateTime WeekStart { get; set; }
}
And this custom attribute
[AttributeUsage(AttributeTargets.All)]
public class UiGridColumn : Attribute
{
public string CellFilter { get; set; }
public string DisplayName { get; set; }
public string Name { get; set; }
public bool Visible { get; set; }
public string Width { get; set; }
}
I want to create a List<UiGridColumn> for each field with only the provided values (I don't want a null for the skipped properties).
Is it possible to create a List<UiGridColumn> where each List item has only the provided values? (I fear this isn't possible, but thought I would ask) If so, how?
If not, my second preference would be a string array like this:
[{"name":"fullName","visible":false,"width":"90"},{"name":"weekStart","cellFilter":"date"}]
I would prefer to not loop through each property and attribute and argument to manually build the desired JSON string, but I haven't been able to find an easy way to do it otherwise.
public List<Object> GetUiGridColumnDef(string className)
{
Assembly assembly = typeof(DynamicReportService).Assembly;
var type = assembly.GetType(className);
var properties = type.GetProperties();
var columnDefs = new List<object>();
foreach (var property in properties)
{
var column = new Dictionary<string, Object>();
var attributes = property.CustomAttributes;
foreach (var attribute in attributes)
{
if (attribute.AttributeType.Name != typeof(UiGridColumn).Name || attribute.NamedArguments == null)
continue;
foreach (var argument in attribute.NamedArguments)
{
column.Add(argument.MemberName, argument.TypedValue.Value);
}
}
columnDefs.Add(column);
}
return columnDefs;
}
Is there a better way to do this?

Answer 1

If I understand your question correctly, you want to serialize the list of attributes applied to the properties on a class?
If so, you can make a helper method to do it like this:
public static string SerializeAppliedPropertyAttributes<T>(Type targetClass) where T : Attribute
{
var attributes = targetClass.GetProperties()
.SelectMany(p => p.GetCustomAttributes<T>())
.ToList();
JsonSerializerSettings settings = new JsonSerializerSettings
{
NullValueHandling = NullValueHandling.Ignore,
Formatting = Formatting.Indented
};
return JsonConvert.SerializeObject(attributes, settings);
}
Then use it like this:
string json = SerializeAppliedPropertyAttributes<UiGridColumn>(typeof(PayrollReport));
You will end up with this output, which is pretty close to what you're looking for:
[
{
"Name": "fullName",
"Visible": false,
"Width": "90",
"TypeId": "UiGridColumn, JsonTest, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"
},
{
"CellFilter": "date",
"Name": "weekStart",
"Visible": false,
"TypeId": "UiGridColumn, JsonTest, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"
}
]
You'll notice the TypeId property from the base Attribute class is included, and also the property names are not camel cased. To fix that, you'll need to use a custom contract resolver:
public class SuppressAttributeTypeIdResolver : CamelCasePropertyNamesContractResolver
{
protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
{
JsonProperty prop = base.CreateProperty(member, memberSerialization);
if (member.DeclaringType == typeof(Attribute) && member.Name == "TypeId")
{
prop.ShouldSerialize = obj => false;
}
return prop;
}
}
Add the resolver to the serialization settings in the helper method and you should be good to go:
JsonSerializerSettings settings = new JsonSerializerSettings
{
NullValueHandling = NullValueHandling.Ignore,
ContractResolver = new SuppressAttributeTypeIdResolver(),
Formatting = Formatting.Indented
};
Now the output should look like this:
[
{
"name": "fullName",
"visible": false,
"width": "90"
},
{
"cellFilter": "date",
"name": "weekStart",
"visible": false
}
]
Demo fiddle: https://dotnetfiddle.net/2R5Zyi