CODEWITHSUNDEEP
c#.netlinqproperties
Matt
Matt

Reputation: 26971

Enumerating through an object's properties (string) in C#

Let's say I have many objects and they have many string properties.

Is there a programatic way to go through them and output the propertyname and its value or does it have to be hard coded?

Is there maybe a LINQ way to query an object's properties of type 'string' and to output them?

Do you have to hard code the property names you want to echo?

Upvotes: 50

Views: 39904

Answers (4)

Martin Liversage
Martin Liversage

Reputation: 106816

You can get all the properties of a type by using the GetProperties method. You can then filter this list using the LINQ Where extension method. Finally you can project the properties using the LINQ Select extension method or a convenient shortcut like ToDictionary.

If you want to limit the enumeration to properties having of type String you can use this code:

IDictionary<String, String> dictionary = myObject.GetType()
  .GetProperties()
  .Where(p => p.CanRead && p.PropertyType == typeof(String))
  .ToDictionary(p => p.Name, p => (String) p.GetValue(myObject, null));

This will create a dictionary that maps property names to property values. As the property type is limited to String it is safe to cast the property value to String and the type of the returned type is IDictionary<String, String>.

If you instead want all properties you can do it like this:

IDictionary<String, Object> dictionary = myObject.GetType()
  .GetProperties()
  .Where(p => p.CanRead)
  .ToDictionary(p => p.Name, p => p.GetValue(myObject, null));

Upvotes: 16

Karl Wenzel
Karl Wenzel

Reputation: 2482

If your goal is simply to output the data stored in the object's properties using a human-readable format, I prefer to simply serialize the object into JSON format.

using System.Web.Script.Serialization;
//...

string output = new JavaScriptSerializer().Serialize(myObject);

Upvotes: 4

Ben M
Ben M

Reputation: 22492

Use reflection. It's nowhere near as fast as hardcoded property access, but it does what you want.

The following query generates an anonymous type with Name and Value properties for each string-typed property in the object 'myObject':

var stringPropertyNamesAndValues = myObject.GetType()
    .GetProperties()
    .Where(pi => pi.PropertyType == typeof(string) && pi.GetGetMethod() != null)
    .Select(pi => new 
    {
        Name = pi.Name,
        Value = pi.GetGetMethod().Invoke(myObject, null)
    });

Usage:

foreach (var pair in stringPropertyNamesAndValues)
{
    Console.WriteLine("Name: {0}", pair.Name);
    Console.WriteLine("Value: {0}", pair.Value);
}

Upvotes: 86

Axl
Axl

Reputation: 8502

How about something like this?

public string Prop1
{
    get { return dic["Prop1"]; }
    set { dic["Prop1"] = value; }
}

public string Prop2
{
    get { return dic["Prop2"]; }
    set { dic["Prop2"] = value; }
}

private Dictionary<string, string> dic = new Dictionary<string, string>();
public IEnumerable<KeyValuePair<string, string>> AllProps
{
    get { return dic.GetEnumerator(); }
}

Upvotes: -3

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