GetEnvironmentVariableValueString

public string GetEnvironmentVariableValueString(string schemanameEnvVarDefinition)
{
    tracingService.Trace("Calling GetEnvironmentVariableValueString");

    // Retrieve Environment Variable Definition (i.e. default)
    QueryExpression queryEnvVarDefinition = new QueryExpression("environmentvariabledefinition")
    {
        ColumnSet = new ColumnSet("defaultvalue", "environmentvariabledefinitionid")
    };
    queryEnvVarDefinition.Criteria.AddCondition("schemaname", ConditionOperator.Equal, schemanameEnvVarDefinition);

    EntityCollection collectionEnvVarDefinition = crmService.RetrieveMultiple(queryEnvVarDefinition);

    if (collectionEnvVarDefinition.Entities.Count != 1)
    {
        throw new Exception("Environment variable not found.");
    }

    Entity entityEnvVarDefinition = collectionEnvVarDefinition.Entities[0];
    string defaultvalueEnvVarDefinition = entityEnvVarDefinition.GetAttributeValue<string>("defaultvalue");

    // Retrieve Environment Variable Value (i.e. current)
    QueryExpression queryEnvVarCurrentValue = new QueryExpression("environmentvariablevalue")
    {
        ColumnSet = new ColumnSet("value")
    };
    queryEnvVarCurrentValue.Criteria.AddCondition("environmentvariabledefinitionid", ConditionOperator.Equal, entityEnvVarDefinition.Id);

    EntityCollection collectionEnvVarCurrentValue = crmService.RetrieveMultiple(queryEnvVarCurrentValue);

    if (collectionEnvVarCurrentValue.Entities.Count != 1)
    {
        // Return current value if it exists, otherwise return default value
        return defaultvalueEnvVarDefinition;
    }

    Entity entityEnvVarCurrentValue = collectionEnvVarCurrentValue.Entities[0];
    string valueEnvVarCurrentValue = entityEnvVarCurrentValue.GetAttributeValue<string>("value");

    return valueEnvVarCurrentValue;
}