Can anyone tell how to update table rows dynamically in entity framework? I am new in entity framework. Thanks in advance.
This is a pretty general question, but what you need to do is basically this:
Access your data context.
Get a given object (/record) from your context (/database).
Change the object.
Call SaveChanges() on the data context.
If you are learning EF a site that helped me a lot when I was learning it is http://msdn.microsoft.com/en-us/library/gg696194(VS.103).aspx. It contains lots of information in problem/solution format. You can also look at this book:
http://www.amazon.com/Programming-Entity-Framework-Building-Centric/dp/0596807260/ref=sr_1_1?ie=UTF8&qid=1355991856&sr=8-1&keywords=entity+framework
or this book:
http://www.amazon.com/Programming-Entity-Framework-Code-First/dp/1449312942/ref=sr_1_4?ie=UTF8&qid=1355991858&sr=8-4&keywords=entity+framework
which are both quite useful depending on whether you wish to use the designer or Code First.
Related
So I've found similar questions, but could really use some help! I have an Entity Framework Application with a whole bunch of tables. I've had to add a new table, and I understand that I can get the model to update using the wizard from .edmx file. The problem is that I REALLY don't want to udpate all of the other models. I've added validation for my models as they're being used in forms, regenerating these models will get rid of all that code. Any suggestions? Thanks a lot.
You won't be able to preserve the changes you made to the auto-generated classes as part of the .edmx.
This may not be the answer you want to hear, but your situation is one of many reasons to use different classes for your user submitted data (i.e. web form in your case).
A few other reasons you should separate your models:
Prevent over-posting which could result in bad data or even security issues
Keep your data models clean and simple by avoiding having UI specific properties (e.g. SelectList which is an object to help populate <select> elements, but doesn't need to be part of the database)
I have ben following through a tutorial that shows how to get started creating a Web Forms Application in ASP.NET...and have got to the part where you create Data Classes. These assume you are starting from scratch and generating the database from code - however - I already have a database created and populated from elsewhere.
Entering line by line to create the Class for each table seems very laborious. (I'm using VB.Net and VS 2013 by the way)
Q1. Can anyone help by suggesting a more automated way of doing this? Surely there is a tool to grab the schema?
Q2. Although the tutorial mentions Entity Framework and Code Behind briefly - having done some reading and research - I am very confused by all of the different terms for data access. Am I using ADO.NET ?? Is the methodology called Code Behind as opposed to something else? Are there better ways to connect to a database and Read/Update/Delete records.
Q3. If I want to use a Data Grid to show the data do I use the generated classes to do this - or just 'bind' the grid directly to the database?
I have been a developer for 40 years but the newer .Net models are causing me some confusion so any advice gratefully received. (and any simple books or tutorials that can be suggested would be helpful).
Thanks
Q1: What you want is to generate "EF Designer from database" by using a Entity Data Model.
In your project add a new item and look under "Data".
What this technique does is auto generating entity classes from your predefined database.
Q2: I suggest you read Getting started with Entity Framework. "Database First" is just a description of how you want to use the Entity framework - by saying you already have a database structure.
Q3: In this case if you use Entity Framework and the "database first" mechanism to generate entities you can databind the gridview from the result of a entity LINQ query, please see this example: Tutorial: Databinding
I'm not an ASP.NET programmer, but, as it happens in life, I had to do some minor projects using it. Now came another one in which I have to implement some custom solutions and I haven't figured it out yet - I need some tip or maybe a piece of advice like "don't go that way" ;)
Previously it was simple - there was a table in DB, there was an adequate model and a view that worked with it - worked like charm. Now it's a little bit more complicated.
The "site" is going to contain, shortly and generally speaking, a survey - but a fully configurable one, unfortunately. In another product there's gonna be a configuration manager that will allow user to define pages, block types, questions, steps and so on and will generate an XML.
For the time being, in accordance with the specification, in the site's database I'm going to have only one table which will contain just a key and the XML generated by the configurator (and maybe some additional, not important information). Now - I need to parse this XML and build the site containing pages and other elements corresponding to it.
And that WOULD not be a problem, but I don't really know how to work that way using asp.net + mvc and can't find any piece of advice that would help me anyhow. Should I create an object that would somehow fake being a model and allow me to work for example on a dataset generated from XML? Or just create a model of the mentioned table and work with the XML directly on the view (I don't like even such an idea itself)? Or - having to do something like that - just give up on MVC and use only "clear" ASP.NET? Or maybe something else?
I'll be very grateful for any help.
And I hope I described what I need understandably ;)
If the XML documents have a schema defined then you can easily generate a class that matches the document using the xsd.exe tool. The document can then be deserialized into an instance of that class using existing functionality in the .Net framework. Just google .Net Xml serialization :-)
Now, if you don't have a schema you could create one if you are sure that you know the format of the Xml. Alternatively you could create a class that matches the format you expect to get and then parse the Xml manually. This last option is much more work, so I wouldn't recommend it.
In any case, the class you end up with should contain all the data you need from the Xml document and can then be used as the Model in your MVC page. As long as you can use the standard Xml deserialization technique then this should be quite easy and painless.
I'm attempting to setup Entity Framework using Code First on an existing database. The database isnt in great shape (poor naming convention and some constraints are needed). The application I'm building is an MVC app. I have a "Model", "Repository", and "Web" (mvc) tiers.
To setup EF and map my model objects (POCO objects), is it required that I match my objects to database tables? Can I, instead, use my own stored procedures for CRUD operations? Would it help if I use WCF data services?
I'm planning on using fluent configurations to map my objects, but having some issues due to the database schema. I'm know considering redesigning the database just to get EF to map correctly. Any suggestions would be greatly appreciated!!
Looks awfully similar to this question:
Does Entity Framework Code First support stored procedures?
The answers there may be helpful to you, as well as the discussion surrounding how Code First and Stored Procedures don't make a whole lot of sense.
Wow, Julie Lerman answered!
Yes, it's possible, but not particularly easy. In particular, you must call context.Database.SqlQuery<T>() where T is the entity type you want to return, and your SQL must match up to that entity type. Otherwise, you will have to massage a result set into a type.
In general, you will have to do most of this manually, although you could probably figure out a T4 template to generate it for you, or maybe use some other tool like CodeSmith.
I am trying out DevExpress Xtrareports, but have asimple problem that I am not able to find an answer to.
In an Asp.net website project, I want to add a business object to my report as a datasource and then drag and drop the fields from my new business object data source onto the report designer.
Can some one help explain how i do this.
I asssume I have just missed something.
Thanks
Ian
One way to solve this would be to give the designer a DataSet with one or more DataTables representing your business object. You would of course have to write some code to convert your business object to the data table and back.
As a side note DevExpress have a really good support forum and I have always gotten answers to my questions regarding their products. I recommend you try your question there unless you get a really good answer.