Is it possible to store an IEnumerable<string> in Entity Framework?
I'm using code-first in ASP.NET MVC5 and I have a model that looks a little like this, but ImageUris does not appear as a column in my database (all the other properties do).
public class Product
{
[Key]
public int Id { get; set; }
public string Title { get; set; }
public string Description { get; set; }
public string Condition { get; set; }
public decimal Price { get; set; }
public IEnumerable<string> ImageUris { get; set; }
}
PS: In case you are interested in why I'm storing Uris rather than images themselves, they are uris to Azure Storage Blobs.
You cannot save multiple records in single column of the relational database. There is no such data type that supports this.
You can create a separate table for Image Uris and then store your image Uris there.
Your entity code would look something like this:
public class Product
{
[Key]
public int Id { get; set; }
public string Title { get; set; }
public string Description { get; set; }
public string Condition { get; set; }
public decimal Price { get; set; }
public virtual ICollection<ImageUri> ImageUris { get; set; }
}
public class ImageUri
{
[Key]
public int Id { get; set; }
public string Uri { get; set; }
}
Related
Let's say I have a bike shops that sell various types of bikes: pro, kids, youth, leisure and any mixture. So I have a table of shops that refers/relates to a table of possible types. Now these shops also host events with the same types: events for pros, kids etc again any mixture. And so I have another table of events that also need to refer/relate to the same table of types:
I need to be able in a single quick query get a list of all bike types for a shop or event.
So I figured I'd have 3 main tables: Shops, Events, BikeTypes and two intermediate to link shops and events to bike types:
And I organized my models as:
public class BikeShop
{
public long Id { get; set; }
public string name { get; set; }
public string address { get; set; }
public string phone { get; set; }
}
public class BikeEvent
{
public long Id { get; set; }
public string name { get; set; }
public string description { get; set; }
public DateTime date { get; set; }
public string location { get; set; }
}
public class BikeType
{
public long Id { get; set; }
public string name { get; set; }
public string code { get; set; }
}
public class ShopBikeTypes
{
public long Id { get; set; }
public BikeShop shop { get; set; }
public BikeType biketype { get; set; }
}
public class EventBikeTypes
{
public long Id { get; set; }
public BikeEvent bikeevent { get; set; }
public BikeType biketype { get; set; }
}
With DataCotext:
public class DataContext : DbContext
{
public DbSet<BikeShop> Shops { get; set; }
public DbSet<BikeEvent> Events { get; set; }
public DbSet<BikeType> BikeTypes { get; set; }
public DbSet<ShopBikeTypes> ShopBikeTypes { get; set; }
public DbSet<EventBikeTypes> EventBikeTypes { get; set; }
}
Migration creates correct database structure just as my diagram. Great!
Now how do I make a straight forward query:
get list of all bike types for a shop
get list of all bike types for an event
Is my structure even correct?
Do I need some List<> in the main object models BikeShop and BikeEvent?
EF's include and theninclude seem to require some list?
This feels like such a typical scenario. What's the right way of doing this?
Thank you.
Those are the linq queries that you are asked but when i look at that your class models, i can say they are wrong. U need to define first which relation theyre having. if all of that relation has based on one-to-one, u wont gonna need any List<> in your class models. but if u have one-to-many relation,u gonna need them.
1- get list of all bike types for a shop
return DbContext.Shops
.Include(x>=x.ShopBikeTypes)
.ThenInclude(x=>x.BikeTypes).ToList();
2- get list of all bike types for an event
return DbContext.Events
.Include(x=>x.EventBikeTypes)
.ThenInclude(x=>x.BikeTypes).ToList();
3- Get all data in that relation
return DbContext.BikeTypes
.Include(x>=x.EventBikeTypes)
.ThenInclude(x=>x.Events).AsSplitQuery()
.Include(x=>x.ShopBikeTypes)
.ThenInclude(x>=x.Shops).AsSplitQuery()
.ToList();
it can be a tough query, do not try to use AsNoTracking() because it can cause Cartesian Explosion.
#BerkGarip: thank you for your help. I ended up with this models structure:
public class AShop
{
public long Id { get; set; }
public string name { get; set; }
public string address { get; set; }
public string phone { get; set; }
public List<AShopType> aTypes { get; set; }
}
public class AEvent
{
public long Id { get; set; }
public string name { get; set; }
public string description { get; set; }
public DateTime date { get; set; }
public string location { get; set; }
public List<AEventType> aTypes { get; set; }
}
public class AType
{
public long Id { get; set; }
public string name { get; set; }
public string code { get; set; }
}
public class AShopType
{
public long Id { get; set; }
public AType aType { get; set; }
}
public class AEventType
{
public long Id { get; set; }
public AType aType { get; set; }
}
In order to achieve what I needed using answer from #BerkGarip I figured out that the trick there was to have lists in the 'shop' and 'event' models to the intermediate objects which in turn have a single reference to 'type'. This way database layout is the same and it is many-to-many relationship and I can use 'include' and 'thenInclude' exactly as expected:
return await _context.AShops.Where(x => x.name == "Z")
.Include(x => x.aTypes)
.ThenInclude(y => y.aType)
.ToListAsync();
I want to store below entities into one single table. I am getting response from REST apis which is hierarchical JSON but i need to take that JSON structure and Store as flat structure into sql server database. I am using new .net framework and EF 7.
CampaignID (id)
CampaignTitle (settings.title)
CampaignType (type)
Status (status)
EmailsSent (emails_sent)
SendTime (send_time)
RecipientsListId (recipients.list_id)
RptSmryOpens report_summary.opens
RptSmryUniqOpens report_summary.unique_opens
RptSmryOpenRate report_summary.open_rate
RptSmryClicks report_summary.clicks
RptSmrySubsClicks report_summary.subscriber_clicks
RptSmryClickRate report_summary.click_rate
public class Campaign
{
[JsonProperty("id")]
public string Id { get; set; }
[JsonProperty(#"settings")]
public Settings Settings { get; set; }
[JsonProperty("type")]
public string Type { get; set; }
[JsonProperty("report_summary")]
public ReportSummary ReportSummary { get; set; }
}
public class Settings
{
[JsonProperty("title")]
public string Title { get; set; }
}
public class ReportSummary
{
[JsonProperty("opens")]
public int Opens { get; set; }
[JsonProperty("unique_opens")]
public int UniqueOpens { get; set; }
[JsonProperty("open_rate")]
public double OpenRate { get; set; }
[JsonProperty("clicks")]
public int Clicks { get; set; }
[JsonProperty("subscriber_clicks")]
public int SubscriberClicks { get; set; }
[JsonProperty("click_rate")]
public double ClickRate { get; set; }
}
For example we have profile and organisation. Both have articles.
public class Article
{
public int Id { get; set; }
public string Title { get; set; }
}
public class Profile
{
public int Id { get; set; }
public string Email { get; set; }
public virtual ICollection<Article> Articles { get; set; }
}
public class Organisation
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Article> Articles { get; set; }
}
In this way Article should have two kinds of parent so it should have something like parent type to be able to access a parent when you select articles directly.
public class Article
{
public int Id { get; set; }
public string Title { get; set; }
public int ParentId { get; set; }
public ArticleParentType Parent { get; set; }
}
Is it possible to map it using Entity Framework?
Is it a good idea to do it?
What is the best practice for storing this kind of data?
public class Article
{
public int Id { get; set; }
public string Title { get; set; }
public int ParentId { get; set; }
public ArticleParentType Parent { get; set; }
}
Is it possible to map it using Entity Framework?
Is it a good idea to do it?
Possible yes but not a good idea. The underlying Database can't use a foreign key for Parentid. It would be slow.
What is the best practice for storing this kind of data?
A simple approach, with 2 Nullable parents and without CascadeOnDelete:
public class Article
{
public int Id { get; set; }
public string Title { get; set; }
public virtual Profile Profile { get; set; }
public virtual Organisation Organisation { get; set; }
}
Alternatively you could use inheritance for Article, ie class OrganisationArticle : Article {}
I have a table called MemberCompany which has a record for each company a member has. the model is below. When i query it via a webapi method passing in the memberid, i can see in debug mode that it returns the one company for that member, however when i run it in the browser i can see it returns the entire list of members also. Is it possible to just return a collection of membercompany records without the two referenced tables? I commented out the initial code to include these two tables but they appear to still be being included in the response.
public partial class MemberCompany
{
public int id { get; set; }
public int membership_id { get; set; }
public string company_name { get; set; }
public string company_address1 { get; set; }
public string company_address2 { get; set; }
public string company_town_city { get; set; }
public Nullable<int> company_county { get; set; }
public string company_postcode { get; set; }
public string company_tel { get; set; }
public string company_fax { get; set; }
public string company_email { get; set; }
public string company_contact { get; set; }
public string company_web { get; set; }
public string company_country { get; set; }
public Nullable<System.DateTime> last_updated { get; set; }
public Nullable<decimal> latitude { get; set; }
public Nullable<decimal> longitude { get; set; }
public virtual counties counties { get; set; }
public virtual members members { get; set; }
}
WebAPI
[HttpGet("admin/api/membercompany/member/{member_id}")]
public IEnumerable<MemberCompany> GetByMember(int member_id)
{
var Companies = db.MemberCompanies
// .Include(t => t.counties)
//.Include(t => t.members)
.Where(m => m.membership_id == member_id);
return Companies.AsEnumerable();
}
Turn off lazy loading for the context. My best guess is it's on and the entities are loaded when the graph is serialized...
Note: that's actually a good idea in a web app and I'd recommend you do it globally, so that you don't get bitten by performance issues due to lazy loading later, and always know precisely what you'll return.
Right now I'm learning ADO.NET Entity Framework and there's one thing that I can't explain to myself. Here is a source code from a tutorial I've been using recently:
public class Blog
{
public int BlogId { get; set; }
public string Name { get; set; }
public string Url { get; set; }
public User UserId { get; set; }
public virtual List<Post> Posts { get; set; }
}
public class Post
{
public int PostId { get; set; }
public string Title { get; set; }
public string Content { get; set; }
public int BlogId { get; set; }
public virtual Blog Blog { get; set; }
}
public class User
{
public int UserId { get; set; }
public string Username { get; set; }
public string DisplayName { get; set; }
}
First I thought that the using of List<> is the way to implement Foreign Key-like behaviour but now knowing that's not the case why we need and for what purpose we use List<> in our entites?
To show that Blog have a lot of Posts, when you will build your project in DB will be the relation 1xBlog--->NxPost where N=unlimited. This will show that each Blog can have unlimited amount of Posts