Entity Framework - Linq to Entities - strange issue with Anonymous function - entity-framework

Following is the code, I am trying:
public List<Movie> GetMovies()
{
Func<Movie, Movie> prepareMovieOutput =
(input) =>
{
input.DisplayHtmlContent = String.Empty;
return input;
};
var moviesOutput = from m in db.Movies.ToList()
select prepareMovieOutput(m);
return moviesOutput.ToList();
}
public List<Movie> SearchMovies(string searchTerm)
{
var moviesOutput = db.Movies.Where(m => m.Name.Contains(searchTerm)).ToList();
return moviesOutput.ToList();
}
The GetMovies function is working properly, as it returns List collection after clearing DisplayHtmlContent field, whereas, SearchMovies function is supposed to return Movie collection with DisplayHtmlContent field, but inspite of that it returns that field empty.
If I set DisplayHtmlContent to some fixed value (like, "ABC"),both GetMovies and SearchMovies return the list with all Movie having DisplayHtmlContent field as "ABC" value. I don't understand why the function defined in one method should affect the other one. and also how to fix this issue?
Ideally, I want GetMovies to hold all Movie with that particular field as empty string, and SearchMovies to hold all Movie with that field containing value.
Any help on this much appreciated.

this was due to the use of repository. I have removed it and it started working fine. with having EF 5, I didn't need to use repository

Related

ReSharper 8 - Live Template Macros - HotspotItems

I am currently using ReSharper V8.1. I've only recently began using ReSharper and have found some interest in their LiveTemplate Macros. I've conjured up a solution to return a list of HotspotItems from a constant, similar to ReSharper's predefined macro "Comma-delimited list of values". In the method I take the constant variable of the template parameter and do a split string on them to provide a collection of HotSpotItems. Unfortunately it doesn't work if I use the macro more than one time within a template. Below is an extreme hack job showing my implementation of the method HotspotItems of IMacroImplementation.
I am hoping that someone out there may have done some work in this area and could possibly provide an example of how they've implemented IMacroImplementation which provides a list of items from a constant and also allows for multiple uses within a single template.
Thank you.
public override HotspotItems GetLookupItems(IHotspotContext context)
{
HotspotItems hotSpotItems = null;
foreach (var hotspot in context.HotspotSession.Hotspots)
{
if (hotspot.Expression != null && ((MacroCallExpressionNew)hotspot.Expression).Definition is Macros.DisplayMultipleItems)
{
//hotspot.CurrentValue
var multiItems = ((MacroCallExpressionNew) hotspot.Expression).Definition as DisplayMultipleItems;
if (!multiItems.ItemSet)
{
var expression = hotspot.Expression as MacroCallExpressionNew;
IMacroParameterValueNew baseValue = expression.Parameters[0].GetValue(context.SessionContext.Solution.GetLifetime(), context.HotspotSession);
string templateValue = baseValue.GetValue();
multiItems.ItemSet = true;
if (!string.IsNullOrEmpty(templateValue) && templateValue.Split(',').Any())
{
var lookupItems = templateValue.Split(',').Select(param => new TextLookupItem(param)).Cast<ILookupItem>().ToList();
if (hotSpotItems == null)
hotSpotItems = new HotspotItems(lookupItems);
else
{
foreach (var item in lookupItems)
{
hotSpotItems.Items.Add(item);
}
}
}
}
}
}
return hotSpotItems;
}
You should fire up dotPeek and point it to the ReSharper bin directory and take a look at ListMacroDef and ListMacroImpl, which is the implementation for the comma-delimited list macro.
The definition derives from SimpleMacroDefinition. It gets given the parameters in the call to GetPlaceholder, looks at the first and splits it by comma, returning the first item as the placeholder.
ListMacroImpl is just as simple. Its constructor has an [Optional] parameter of type MacroParameterValueCollection. This is the list of parameter values specified in the hotspot editor. You'll want to check for null and take the first parameter, which will be your delimited list. It then overrides GetLookupItems and returns HotspotItems.Empty if the parameter value is null, or parses the value and returns a list of TextLookupItem.
You don't need to look at the session and list of hotspots - that will get you all hotspots in the session, when you're only interested in the current hotspot, and ReSharper will create a new IMacroImplementation for each hotspot and give you those values in your constructor.

In C#, how do I get a distinct value from an IEnumerable using LINQ?

I have an IEnumerable variable that I want to extract a distinct value from. I know all the entries in the rows of the list have the same value, I just need to get that value.
The method returns an IEnumerable.
The row in the IEnumerable is defined as:
QuoteCovId
AdditionalInterestId
AdditionalInterestsAffiliateId
AdditionalInterestsLastName
AdditionalInterestsBusinessAddrLine1
AdditionalInterestsBusinessCity
AdditionalInterestsBusinessState
AdditionalInterestsBusinessZip
Sampel of code:
IadditionalInterestData = AdditionalInterestData.GetAdditionalInterests(MasterPkgID, Requestor);
// Using linq.
var quotes = from ai in IadditionalInterestData
select Distinct(ai.QuoteCovId);
// Iterate thru to get the 1 value.
foreach (int QuoteCovId in quotes)
{
quoteID = QuoteCovId;
}
var quoteId = AdditionalInterestData.GetAdditionalInterests(MasterPkgID, Requestor)
.FirstOrDefault().Select(f => f.QuoteCovId);
But that method:
AdditionalInterestData.GetAdditionalInterests(MasterPkgID, Requestor);
returns me an IEnumerable which I will use further in my application. Which is what I need.
So how will your suggestion still give me that IEnumerable and give me the quote value which happens to be the same in the collection?
var quoteId = AdditionalInterestData.GetAdditionalInterests(MasterPkgID, Requestor).FirstOrDefault().Select(f => f.QuoteCovId);
Also, I just added your line of code as is and I get an error statement.

FluentMongo throwing error all of a sudden

I am using FluentMongo and the MongoDBCSharpDriver. My code was working fine for a while, but after updating my MongoCSharpDriver, I now I keep getting this error when I try to query the database:
"Discriminators can only be registered for classes, not for interface MyLib.Services.IRepoData."
The interface IRepoData is just one that I use for all my objects saved to MongoDB. It just defines _id for everything. Here is the line that is breaking:
var item = Collection.AsQueryable().SingleOrDefault(a => a.Id == itemID);
Can anyone shed some light on this one? If I just use .SingleOrDefault() with no lambda then it works fine, its passing a lambda that breaks it.
EDIT
In case this helps...
var Collection = GetCollection<MyClass>();
private MongoCollection<T> GetCollection<T>() where T : class, new()
{
string typeName = typeof(T).Name;
var collection = db.GetCollection<T>(typeName, safeMode);
return collection;
}
Found it! I was calling GetCollection() from within another generic method, like this:
public T Save<T>(T item) where T : class, IRepoData, new()
{
GetCollection<T>().Save(item);
}
This caused GetCollection to see T as the interface instead of the actual instance class. GetCollection works fine anywhere else.
For anyone else with this problem, I just used a low level query like this instead... Collection.FindOneAs<T>(Query.EQ("Id", itemID.ToString()));

NullReferenceException while trying to including a one-to-many relationship item after saving parent

Framework: I'm using using MVC 3 + EntityFramework 4.1 Code-First.
Concept: One Legislation entity has many Provision entities. The idea is that the user enters a Legislation entity, that gets saved then the function that saves it passes it along to another function to see whether that Legislation has a ShortTitle. If it does, then it formats it into a properly worded string and includes it as the Legislation's first Provision, then saves the changes to db.
Issue: The problem is, I've tried coding it in different ways, I keep getting a NullReferenceException, telling me to create a new object instance with the "new" keyword, and points me to the savedLegislation.Provisions.Add(provision); line in my second function.
Here are the two functions at issue, this first one saves the Legislation proper:
public Legislation Save(NewLegislationView legislation)
{
Legislation newLegislation = new Legislation();
// Simple transfers
newLegislation.ShortTile = legislation.ShortTile;
newLegislation.LongTitle = legislation.LongTitle;
newLegislation.BillType = legislation.BillType;
newLegislation.OriginatingChamber = legislation.OriginatingChamber;
newLegislation.Preamble = legislation.Preamble;
// More complicated properties
newLegislation.Stage = 1;
this.NumberBill(newLegislation); // Provides bill number
newLegislation.Parliament = db.LegislativeSessions.First(p => p.Ending >= DateTime.Today);
newLegislation.Sponsor = db.Members.Single(m => m.Username == HttpContext.Current.User.Identity.Name);
// And save
db.Legislations.Add(newLegislation);
db.SaveChanges();
// Check for Short titles
this.IncludeShortTitle(newLegislation);
// return the saved legislation
return newLegislation;
}
And the second function which is invoked by the first one deals with checking whether ShortTitle is not empty and create a Provision that is related to that Legislation, then save changes.
public void IncludeShortTitle(Legislation legislation)
{
var savedLegislation = db.Legislations.Find(legislation.LegislationID);
if (savedLegislation.ShortTile.Any() && savedLegislation.ShortTile.ToString().Length >= 5)
{
string shortTitle = "This Act may be cited as the <i>" + savedLegislation.ShortTile.ToString() + "</i>.";
var provision = new Provision()
{
Article = Numbers.CountOrNull(savedLegislation.Provisions) + 1,
Proponent = savedLegislation.Sponsor,
Text = shortTitle
};
savedLegislation.Provisions.Add(provision);
db.SaveChanges();
}
}
I've been researching how SaveChanges() works and whether it is properly returning the updated entity, it does (since I get no issue looking it up in the second function). If it works properly, and the legislation is found and the provision is newly created in the second function, I don't see what is the "null" reference it keeps spitting out.
The null reference in this case would be savedLegislation.Provisions. The Provisions collection won't be initialized to a new List<Provision> when EF returns your Legislation instance from the db.Legislations.Find(...) method.
The first thing I'd try is something like this:
var savedLegislation = db.Legislations
.Include("Provisions")
.First(l => l.LegislationID == legislation.LegislationID);
... but I'd also consider just using the legislation instance that was passed into the method rather than fetching it from the database again.

DataReader with duplicate column names

What is the best way of handling trying to get data from a DataReader that has more than one column with the same name?
Because of the amount of work involved and because we don't want to lose support from a vendor by changing the stored procedures we are using to retrieve the data, I am trying to find another way to get access to a column that shows up more than once in a datareader without having to rewrite the stored procedures.
Any Ideas?
EDIT:
Ok, the function that actually populates from a datareader is used in multiple places so there is a possibility that the function can be called by different stored procedures. What I did was to do a GetName using the index to check if it is the correct column, and if it is, then pull its value.
If you know the index of the column, then access it by the index.
Can't you use column ordinals? 0 for the 1st, 1 for the 2nd, and so on?
You will have to reference the column by index no; i.e. reader[5].ToString(); to read the data in column 5.
Based on original poster's approach described in the "Edit" paragraph, here's an extension method that will give the value based on the column name and the index of that name, e.g., 0 for the first instance of name, 1 for the second, etc:
using System;
namespace WhateverProject {
internal static class Extentions {
// If a query returns MULTIPLE columns with the SAME name, this allows us to get the Nth value of a given name.
public static object NamedValue(this System.Data.IDataRecord reader, string name, int index) {
if (string.IsNullOrWhiteSpace(name)) return null;
if (reader == null) return null;
var foundIndex = 0;
for (var i = 0; i < reader.FieldCount; i++) {
if (!reader.GetName(i).Equals(name, StringComparison.CurrentCultureIgnoreCase)) continue;
if (index == foundIndex) return reader[i];
foundIndex++;
}
return false;
}
}
}
Use it thus:
var value1 = reader.NamedValue("duplicatedColumnName", 0);
var value2 = reader.NamedValue("duplicatedColumnName", 1);