Question

I am trying accomplish creating a c# statement dynamically to avoid the use of the switch statement shown below. I looked into CodeSnippetStatement class but could not make it work.

dynamic apps;

        switch (entity)
        {
            case "entity_1":
                apps = Xrm.Entity_1Set.SingleOrDefault(a => a.Id.Equals(guid));
                break;
            case "entity_2":
                apps = Xrm.Entity_2Set.SingleOrDefault(a => a.Id.Equals(guid));
                break;
            case "entity_3":
                apps = Xrm.Entity_3Set.SingleOrDefault(a => a.Id.Equals(guid));
                break;

…

I would like to do something like this (pass entity dynamically into string and convert the statement to execute in run time):

apps = CodeSnippetStatement(String.Format(“Xrm.{0}Set.SingleOrDefault(a => a.Id.Equals(guid)”, entity) );

Is that possible??

Answer 1

Assuming Entity_1Set is a public property of Xrm, you could use reflection:

using System.Reflection; // at the top of your code file

var propertyName = "E" + entity.Substring(1) + "Set";
apps = Xrm.GetType().GetProperty(propertyName ).GetValue(Xrm);

This will only work if Xrm is an instance of a class (not a static class reference).

Note that reflection is slower than direct access of a property. This time cost is not much if you are only doing this occasionally. But inside a loop, it could add up.

Another technique would be to cache your EntitySet instances into a dictionary:

private Dictionary<string, EntitySet> entityMappings; // at the top of your class

var xrm = GetXrmFromSomewhere();
entityMappings = new Dictionary<string, EntitySet>
{
    { "entity_1", xrm.Entity_1Set },
    { "entity_2", xrm.Entity_2Set },
    { "entity_3", xrm.Entity_3Set }
};

Then you would just need to do:

var app = entityMappings[entity].SingleOrDefault(a => a.Id.Equals(guid));