Develop Reference

getting properties of dynamic type c#

Consider the following code:
foreach (Type formType in allFormsToLoopThrough)
{
var nonPriorityForm = _context.Query(formType);
foreach (var nonpriority in nonPriorityForm)
{
var name = nonpriority.GetType().Name;
MyWorkAssignmentDTO form = new MyWorkAssignmentDTO
{
FormName = formType.Name
Id = nonpriority.Id
};
}
}
This snippet is looping thought a list of types.
Each type is taken from the list and passed to a Query function that returns an IQueryable - basically a list of records in a given table in a database that matches the type.
Then for each of the record sets that come back, I want to loop through those and from each create a new instance of MyWorkAssignmentDTO. I am only interested in a form name (which I can get from formType) but I cannot get nonpriority.Id
I know for sure that every nonpriority will have an Id once it is resolved in the loop.
What I can't do is implement this to work at run time.
Can anyone help?

I was able to use the dynamic keyword instead of var. While I lose compile time validation, this gets me over the line when I know for sure there will be an Id.
dynamic nonPriorityForm = _context.Query(formType);

Does IList<> guarantee order of added items in C#

I am using Seed() method of Configuration.cs class for filling data in database when using Update-Database command.
Among other things I am creating list of EventCategory objects like this:
private IList<EventCategory> CreateEventCategoriesTestDefinition()
{
eventCategories = new List<EventCategory>();
var eventCategoryRecruitment = new EventCategory("Recruitment");
eventCategories.Add(eventCategoryRecruitment);
var eventCategoryInternship = new EventCategory("Internship");
eventCategories.Add(eventCategoryInternship);
var eventCategoryTrainingPrograms = new EventCategory("Training Programs");
eventCategoryTrainingPrograms.Events
.Add(new Event("Managerial Training Program 2012-2014", eventCategoryTrainingPrograms));
eventCategories.Add(eventCategoryTrainingPrograms);
var eventCategoryEmployee = new EventCategory("Employee & Team Potential");
eventCategories.Add(eventCategoryEmployee);
return eventCategories;
}
Adding element by element. eventCategory is just a private property:
private IList<EventCategory> eventCategories;
From Seed() method I am calling CreateEventCategoriesTestDefinition()
Almost everything is good but when I go to database to check data I have noticed that data in EventCategory table doesn't have correct order:
As you can see it on a picture Internshipand Training Programs switched positions comparing to order of adding inCreateEventCategoriesTestDefinition() method.
Does anybody knows what is happening here? Why order of adding is not preserved? I know it should be perserved in List<>, but is not the same for IList<>?
Or this is maybe has something to do with EntityFramework?

If you are relying upon the database for your sorting order then either.
Turn auto-id incrementation off and specify your own ID
EventCategory(int id, string name)
If you have to use database identity then instead try using a sort order (int) column for your objects
EventCategory(string name, int sortOrder)
Either way, you cannot guarantee that you'll get a sorted List persisted to the database. I cant say for certain your use case here, but you shouldn't reply on SQL to sort your objects for you, but when querying the database use linq to order them before binding to a view.
e.g.
var mySortedCategories = dbContext.EventCategories.OrderBy(x => x.Name).ToList();

Dapper Multiple Results From single query

Hi i am trying to get to grips with Dapper.
My situation is i want to pull two values from a query into two separate strings. Im not sure if i am going about this in the correct way, but this is what i am doing:
string sql = #"Select type, name
FROM ZipData
WHERE Zip = #zip";
using (var multi = conn.QueryMultiple(sql, new { zip = zip }))
{
string result = multi.Read<string>().SingleOrDefault();
}
And i am getting Cannot access a disposed object. Object name: 'GridReader'. when trying to read the second string.The thing is it gets the first value correctly and has both the fields in in the reader i am trying to get. Im sure im misusing the api.
What am i doing wrong here? Ive googled but can find a specific example.

You are mis-using QueryMultiple. That is defined for compound SQL statements that return multiple result sets. Something like:
SELECT Foo FROM MyTable;
SELECT Bar FROM MyOtherTable;
On the other hand, you are trying to get two different columns from a single result set, so you should just use the normal Query method:
var result = conn.Query(sql, new { zip = zip }).Single();
var type = result.type;
var name = result.name;
Query returns an enumerable (because generally a query can return multiple rows). It appears that you only want one row, however, so we invoke .Single at the end to just get that row. From there, the return type is dynamic so you can simply refer to the properies implied by the columns in your SELECT statement: type and name.

Using Query datatype in C#

I have a piece of code which returns a Sales Order from AX. In that record im using the querySalesLine method but I'm not sure where I go from there to get all the lines attached to the order below is my code:
AxaptaRecord OrderRecord = (AxaptaRecord)ax.CallStaticClassMethod("OnlineOrder", "getSalesOrder", salesRef);
if(OrderRecord.Found)
{
AxaptaObject Lines = (AxaptaObject)OrderRecord.Call("querySalesLine");
}
How would I then use this Lines object to retrieve all of the items attached to this order? I know that the querySalesLine returns a Query object but not sure what to do next.

You should create a QueryRun object, then use that object to read the lines.
var qLines = (AxaptaObject)OrderRecord.Call("querySalesLine");
var qrLines = ax.CreateAxaptaObject("QueryRun", qLines);
To read the lines use this answer.
The Query is a static description of the query.
The QueryRun uses the query to find the records.

Parse XML using LINQ and fill existing object's properties rather than creating a new one

What I have now is the following code:
Tutorial tutorial =
(from tutorial in xmlDoc.Descendants("Tutorial")
select new Tutorial
{
Author = tutorial.Element("Author").Value,
Title = tutorial.Element("Title").Value,
Date = DateTime.Parse(tutorial.Element("Date").Value),
}).First();
myTutorial.Author = tutorial.Author;
myTutorial.Title = tutorial.Title;
myTutorial.Date = tutorial.Date;
myTutorial is passed from another method. And the code below has to 'fill' it.
The question is: Is there a way to create a LINQ query, which will assign values to the properties of an existing object, rather that creating a new one.
I would like my code to look something like this:
Tutorial tutorial =
(from tutorial in xmlDoc.Descendants("Tutorial")
select myTutorial
{
Author = tutorial.Element("Author").Value,
Title = tutorial.Element("Title").Value,
Date = DateTime.Parse(tutorial.Element("Date").Value),
});
The problem I have is:
I have an object which initially only has half of it's properties set, later I need to fill the rest of the properties. This needs to be done asynchronously.
My Approach:
I use WebClient's asynchronous method DownloadStringAsync to download XML file. In the event handler I wan't to fill an object with the properties it misses. And that's why I would like to directly pass values to my object rather than creating a new one.
Please let me know if it is not the best approach.

OK, this is pure evil:
var dropThis =
(from tutorial in xmlDoc.Descendants("Tutorial")
select new
{
Author = (myTutorial.Author = (string)tutorial.Element("Author")),
Title = (myTutorial.Title = (string)tutorial.Element("Title")),
Date = (myTutorial.Date = (DateTime)tutorial.Element("Date")),
}).First();

LINQ functional queries are actually designed in such way, that they shouldn't modify existing objects or collections, i.e. preserve state (although there are ways (hacks?) to do so).
But you can pretty easily implement reflection-based method to achieve what you want.

I noticed this question and felt the need to add another dirty solution. How about Extension methods?
public static void AddTo(this IEnumerable<Tutorial> source, Tutorial projection)
{
if (source.Count() == 0)
return;
projection.Title = source.First().Title;
projection.Author = source.First().Author;
projection.Date = source.First().Date;
}
Now you can just call it to add to your current tutorial. Also, I recommend using (string) instead of .Value so you avoid null reference exceptions.
tutorialXml
.Descendants("Tutorial")
.Select(tutorial => new Tutorial
{
Author = (string) tutorial.Element("Author"),
Title = (string) tutorial.Element("Title"),
Date = DateTime.Parse((string) tutorial.Element("Date")),
})
.AddTo(myTutorial);
Anyway, Good luck. Just wanted to add a dirty solution to this ball of mud.