I'm experimenting with Spring4D 1.2's simple ORM (Marshmallow). I could get it to work pretty well but I can't find out how to have it update an existing database with a new schema.
For instance, in the "GettingStarted" project, I added one property to the data model:
[Entity]
[Table('Products')]
TProduct = class
{...}
[ColumnAttribute('PRODUCTINFO',50)]
property Info: string read fInfo write fInfo;
No matter what, I can't get the framework to update the schema if the database already exists.
What am I missing ? Must I do that manually outside the framework ?
Schema update is currently not supported nor planned from my side.
Generating the necessary drops and recreate would be reasonably easy but that is only part of the story as you probably want to keep any existing data. From using SQL Server Data Tools I know how deep this rabbit hole can go.
Related
I have a recommendation from Azure to create the following index:
CREATE NONCLUSTERED INDEX [nci_wi_Transactions_71EA7D20388C3F47A9B9EBF2A1C7BA0C] ON [dbo].[Transactions] ([Client_Id]) INCLUDE ([Date], [Description], [Size], [Type]) WITH (ONLINE = ON)
Is it possible to execute this SQL directly from MSSQL without affecting my applications work?
Or do I need to apply some migrations from code-first to keep database context with the correct state anyway?
Actually, #Steve in comment answered and I checked in runtime and
Yes, it is safe to create an index directly from a database, which will not affect applications, used not changed DbContext.
This is probably the single biggest time-waster I have: I must have wasted cumulative days trying to get round it.
I'm using Visual Studio 2015 and ASP.NET MVC 5, but don't think this is important - I've had this problem in other versions. I accept that it's based on my ignorance.
I've got a reasonably complicated SQL Server database, and am using database-first model generation. To keep things manageable, I've got about 20 different models, each containing tables on a particular theme.
So let's say I want to generate a model to contain tables to do with the maps in my database. First thing to do is to add a new entity model database:
I want to call my model webMap:
I choose to generate the model from my database:
I've got a perfectly good connection string to the database in my web.config file, so I use that and choose not to save this:
I then choose the tables for which I want to generate classes, and these options:
What happens then is that it doesn't recognise the new database context:
The reason is (I think) in this file:
This has created a class named after a connection string:
If I change the partial class and constructor name like this:
then it solves the problem - until I next need to update the database.
Please forgive my ignorance about what's going on. Although I like what entity frameworks do, I find the opacity of what's going on hard to work with. Could any kind person tell me what I'm doing wrong, without delving into T4 transformations? I've tried cleaning my solution and running custom tools, by the way. Thank you!
Open the edmx file in the designer and click somewhere inside to select the conceptual model in the Properties window. Now look at Entity Container Name property. The value should be Entities - I think derived from your connection string name and no way to be specified during the Add wizard steps.
Simply change it to the desired name of the context (like webMap), save/build and you are done.
But make sure the Namespace and Entity Container Name property values are different.
Many thanks to Ivan and garret for their answers. I've collated the information and put here a procedure which worked for me. I don't claim to understand fully what's going on (but surely the point of a framework like this is that I shouldn't need to?).
Here's how I managed to create my model. There are 6 steps. I don't know which of them can be omitted, but following them all solved my problem.
Step 1 - Delete any existing models referencing tblMap
I found that I had inadvertently created another model. Doing a global search for (in my case) webMap can help find if you are in the same position.
Step 2 - clear the web.config file connection strings
I don't understand why, but it appears that the connection strings in your web.config file show up as conflicting names in code. So I did a search for webMap in my web.config file and deleted all connection strings containing it. I think this is the step that I had previously omitted.
Step 3 - Clean and rebuild the solution
I cleaned the solution (no idea if this was necessary), then rebuilt it to ensure that the only errors I had left were in my code referencing the webMap database context which no longer existed.
Step 4 - Follow the steps to add an ADO entity model
But ... call the item name in the first screen something like webMapModel, the connection string something like webMapEntities (and choose to save this in the web.config file) and the namespace something like webMapNamespace. Note that none of these is the webMap name I want to end up with.
Step 5 - Change the entity container name
Double-click on the model .edmx file which has been created to open it (this might not be necessary - it may be open already). Click on the white background of the model to deselect any entities. Press F4 to bring up properties.
Change the entity container name to webMap as shown above.
Step 6 - Rebuild your solution
At this point all my errors disappeared!
Name of Your context, should be different than namespace.
Try to use this configuration:
And in next screen:
And yes, it will add next connection string to web.config, but it's ok.
In my MVC 5 application with EF 6.0, I want to insert 200+ records of Product into database using Entity Framework in one hit.
[1]One way is to convert list of records into XML and pass to Stored procedure.
[2] If I use DbContext.Add() , this will fire for every record ( create insert script internally).
[3]If I traverse list of product and pass each record to Stored Procedure, I think this is also not good.
What is the best way to do this?
I'm not sure if this question How to pass a table-value parameter will work for you but it is exactly what I'm using to load data into a SQL 2014 data base. Very nice and has been working for 4+ years.
Disclaimer: I'm the owner of the project Entity Framework Extensions
(This library is NOT free)
This library can make your code more efficient by allowing you to save multiples entities at once. All bulk operations are supported:
BulkSaveChanges
BulkInsert
BulkUpdate
BulkDelete
BulkMerge
BulkSynchronize
Example:
// Easy to use
context.BulkSaveChanges();
// Easy to customize
context.BulkSaveChanges(bulk => bulk.BatchSize = 100);
// Perform Bulk Operations
context.BulkDelete(customers);
context.BulkInsert(customers);
context.BulkUpdate(customers);
// Customize Primary Key
context.BulkMerge(customers, operation => {
operation.ColumnPrimaryKeyExpression =
customer => customer.Code;
});
I have several productive Web applications that use EntityFramework.BulkInsert library with this NuGet package. It works fine, but it is no longer maintained, so a better solution is to use the updated version EntityFramework.BulkInsert-ef6-ext.
It is very simple to use:
context.BulkInsert(yourListOfModels);
and it generates BULK INSERT Sql commands that run much faster that classical Enrity Framework individual INSERTs.
I'm working with a (.net4 / mvc3 ) solution file downloaded (from a reputable source) where a connection string exists in web.config but I don't see explicit instructions to create the database and there's no included '.mdf'. The first time I build I got a runtime error regarding lack of permissions to CREATE database. So I created a blank db and made sure the string referenced a SQL user that had .dbo/owner rights to the db just created.
But subsequent builds don't seem to execute that same initialize db script - where ever that's stored.
Where is this 'first use' convention for creating databases documented?
thx
That is a feature of Entity Framework Code First. I am not sure what you are looking for exactly, but searching for "EF Code First Initialization Strategy" might help.
For instance read this article: EF Code First DB Initialization Using Web.Config
I assume you are talking about Entity Framework, which allows you to create the database from an instance of an ObjectContext object, which is used in any of the three approaches in EF (database-, model- and code-first).
Look for a line that actually calls ObjectContext.CreateDatabase(). If one of the supported ADO.NET provides is used (SQL Server or SQL Server CE 4.0) this will generate the required SQL Statements. Assuming the classic Northwind example, you might find something like that:
NorthwindContext context = new NorthwindContext();
if (!context.DatabaseExists())
{
context.CreateDatabase();
}
If this is in fact a code-first application, "lalibi" is right about the initialization strategy which by default doesn't require you to explicitly create the database. (But my guess is, that it actually uses a statement internally very similar to mine).
Is there a way when i add a new entity to my Code First configuration the table gets automatically added so i don't have to worry about updating my DB with new tables?
you can add
Database.SetInitializer(new DropCreateDatabaseIfModelChanges<YourDbContext>());
in you r application start . It will recreate database for you if you have modified your configuration.
And if you do not want to drop and create database (To incremental development) you can use SqlMigrations. http://www.hanselman.com/blog/EntityFrameworkCodeFirstMigrationsAlphaNuGetPackageOfTheWeek10.aspx
From: http://blogs.msdn.com/b/adonet/archive/2010/12/06/ef-feature-ctp5-code-first-walkthrough.aspx
Setting an Initialization Strategy
In the next section we are going to start changing our model which in turn means the database schema needs to change as well. Currently there is no ‘out of the box’ solution to evolve your existing schema in place. Database evolution is something we are currently working on and a sample of the direction we are heading is provided in a recent design blog post.
There is however the opportunity to run some custom logic to initialize the database the first time a context is used in an AppDomain. This is handy if you want to insert seed data for test runs but it’s also useful to re-create the database if the model has changed. In CTP5 we include a couple of strategies you can plug in but you can also write custom ones.
Add a using statement for System.Data.Entity.Database at the top of Program.cs
using System.Data.Entity.Database;
For the walkthrough we just want to drop and re-create the database whenever the model has changed, so at the top of the Main method in my Program class I’ve added the following code
DbDatabase.SetInitializer<ProductContext>(
new DropCreateDatabaseIfModelChanges<ProductContext>());