entity-framework-4.1

Validation failed for one or more entities. See 'EntityValidationErrors' property for more details

由 点点圈 提交于 2019-11-26 01:20:14
问题 I am having this error when seeding my database with code first approach. Validation failed for one or more entities. See \'EntityValidationErrors\' property for more details. To be honest I don\'t know how to check the content of the validation errors. Visual Studio shows me that it\'s an array with 8 objects, so 8 validation errors. This was working with my previous model, but I made a few changes that I explain below: I had an enum called Status, I changed it to a class called Status I

Ignoring a class property in Entity Framework 4.1 Code First

由 懵懂的女人 提交于 2019-11-26 01:14:10
问题 My understanding is that the [NotMapped] attribute is not available until EF 5 which is currently in CTP so we cannot use it in production. How can I mark properties in EF 4.1 to be ignored? UPDATE: I noticed something else strange. I got the [NotMapped] attribute to work but for some reason, EF 4.1 still creates a column named Disposed in the database even though the public bool Disposed { get; private set; } is marked with [NotMapped] . The class implements IDisposeable of course but I don\

Entity Framework Join 3 Tables

由 陌路散爱 提交于 2019-11-26 01:06:34
问题 I\'m trying to join three tables but I can\'t understand the method... I completed join 2 tables var entryPoint = dbContext.tbl_EntryPoint .Join(dbContext.tbl_Entry, c => c.EID, cm => cm.EID, (c, cm) => new { UID = cm.OwnerUID, TID = cm.TID, EID = c.EID, }). Where(a => a.UID == user.UID).Take(10); I would like to include tbl_Title table with TID PK and get Title field. Thanks a lot 回答1: I think it will be easier using syntax-based query: var entryPoint = (from ep in dbContext.tbl_EntryPoint

Entity Framework Join 3 Tables

由 我的梦境 提交于 2019-11-26 00:40:02
I'm trying to join three tables but I can't understand the method... I completed join 2 tables var entryPoint = dbContext.tbl_EntryPoint .Join(dbContext.tbl_Entry, c => c.EID, cm => cm.EID, (c, cm) => new { UID = cm.OwnerUID, TID = cm.TID, EID = c.EID, }). Where(a => a.UID == user.UID).Take(10); I would like to include tbl_Title table with TID PK and get Title field. Thanks a lot I think it will be easier using syntax-based query: var entryPoint = (from ep in dbContext.tbl_EntryPoint join e in dbContext.tbl_Entry on ep.EID equals e.EID join t in dbContext.tbl_Title on e.TID equals t.TID where

What effect(s) can the virtual keyword have in Entity Framework 4.1 POCO Code First?

由 与世无争的帅哥 提交于 2019-11-26 00:26:55
问题 Does the virtual keyword has an effect when used on the properties in EF Code First?. Can someone describe all of its ramifications in different situations? For instance, I know it can control lazy loading -- if you use the virtual keyword on an ICollection/one-to-many relationship property, it will be lazy-loaded by default, whereas if you leave the virtual keyword out, it will be eager-loaded. What other effects can virtual keyword have in EF with POCO entities?. Should I make it default to

One DbContext per request in ASP.NET MVC (without IOC container)

由 让人想犯罪 __ 提交于 2019-11-26 00:25:43
Apologies if this has already been answered, but how do you guarantee one Entity Framework DbContext per request if you are not using an IOC container? (The answers I've come across so far deal with IOC container solutions.) It seems like most solutions hook into the HttpContext.Current.Items dictionary, but how do you guarantee disposal of the DbContext when the request is finished? (Or is disposal not absolutely necessary with an EF DbContext ?) Edit I'm currently instantiating and disposing my DbContext in my controllers, but I also have several separate instantiations of my DbContext in

Generic Repository With EF 4.1 what is the point

由 大兔子大兔子 提交于 2019-11-26 00:10:20
问题 As i dig deeper in to the DbContext, DbSet and associated interfaces, I am wondering why you would need to implement a separate \"Generic\" Repository around these implementations? It looks like DbContext and IDbSet do everything you need and include the \"Unit Of Work\" inside DbContext. Am I missing something here or does it seem people enjoy adding another layer of dependency for no reason. 回答1: You are actually right. DbContext is an implementation of the unit of work pattern and IDbSet

Unique key with EF code first

由 …衆ロ難τιáo~ 提交于 2019-11-25 23:49:24
问题 I have a following model in my project public class Category { public Guid ID { get; set; } [Required(ErrorMessage = \"Title cannot be empty\")] public string Title { get; set; } } and I\'m trying to make Title as unique key, I googled for the solution, but couldn\'t find any. Can any suggest me how to do it, please? 回答1: Unfortunately you can't define it as unique key in code first because EF doesn't support unique keys at all (it is hopefully planned for next major release). What you can do

The relationship could not be changed because one or more of the foreign-key properties is non-nullable

由 蹲街弑〆低调 提交于 2019-11-25 23:06:29
问题 I am getting this error when I GetById() on an entity and then set the collection of child entities to my new list which comes from the MVC view. The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. When a change is made to a relationship, the related foreign-key property is set to a null value. If the foreign-key does not support null values, a new relationship must be defined, the foreign-key property must be assigned

Entity Framework Code First - two Foreign Keys from same table

由 纵然是瞬间 提交于 2019-11-25 22:37:24
问题 I\'ve just started using EF code first, so I\'m a total beginner in this topic. I wanted to create relations between Teams and Matches: 1 match = 2 teams (home, guest) and result. I thought it\'s easy to create such a model, so I started coding: public class Team { [Key] public int TeamId { get; set;} public string Name { get; set; } public virtual ICollection<Match> Matches { get; set; } } public class Match { [Key] public int MatchId { get; set; } [ForeignKey(\"HomeTeam\"), Column(Order = 0
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