I have a knowledge on .Net frameworks like asp.net, asp.net mvc and asp.net web api. Eventhough it is mvc or web api in .Net we get the data from database using few predefined classes. Then we create a model class object using which we send the data to UI. This approach we can say that 'database first approach'. Entity framework also we can use for same approach. I feel very comfortable with this approach.
Now I started study the Python Django. I am confusing a lot in the area of 'Migrations'. I am not comfort with django admin interface and migrations. Because I am very comfortable to write database queries, procedures and triggers.
I just want to bring the data from any database, after analysing will send to Django 'Template'. Remaining all areas of django are comfortable to me. I tried with django rest api's but there also i found 'Migrations' which are confusing me.
Any one please give me appropriate and detailed guidance.
Thanks.
If you mean "Models" instead of "migrations" then well, you can of course bypass the ORM layer completely and do everything with raw sql instead if you whish...
... but seriously that would be a huge waste of time for at least 80% of common use cases. Django's ORM ("Models") actually makes life much easier for everything but really complex queries (analytics or like stuff), and does not prevent you to switch to raw sql for those queries.
NB : I don't have any problem with SQL either (I learned way before 'ORMs' went kind of mainstream) and still use raw SQL when it's the appropriate solution.
Related
If I choose RavenDB for a fairly standard CMS-like web application, what do I lose compared to SQL Server?
EDIT: There is a word "benefits" in the title which is a little controversial term. Maybe I should have said something like "possibilities" or "features", hope it's clear what I'm after.
A few things that come to mind (but I'm new to RavenDB so this is just a few suggestions, some may be wrong, I hope someone would provide a more complete and accurate list):
Quick but customizable administrative interface using ASP.NET Dynamic Data (there is some built-in Silverlight admin application but I'm quite sure that it wouldn't replace a full-fledged admin section in my case)
Possibly some querying capabilities? Or can Raven indexes replace virtually every SQL query I might think of?
Entity Framework integration (I know some people hate EF but I think that being an EF provider means that you can easily publish the data as OData, use EF code-first etc., right?)
Azure deployment (not true according to comments)
Myriad of SQL querying / management tools
A more complete / accurate list would be greatly appreciated.
(Note: I'm not saying that I will need all (or any) of those, I'd just like to understand what's going to be unavailable if I choose RavenDB. Also, please don't discuss RavenDB strengths, I am aware of them and they are easily digestible from the official website.)
You may want to look # these 2 recent blog posts by Ayende (RavenDB creator) on when you should use RavenDB and when you shouldn't.
When should you use ravendb
When should you not use ravendb
Beyond the technology, you should consider your team members as RavenDB is an adjustment in thinking for those of us who have backgrounds in RDBMS. What type of stretch will this be for those involved? Will your users expect reports and what will the say when you tell them that you did not consider answering the questions that they want answered when you create the indexes for the document database? While you get a big boost in productivity when designing and implementing your domain, document databases are different than SQL.
Quick but customizable administrative interface using ASP.NET Dynamic
Data (there is some built-in Silverlight admin application but I'm
quite sure that it wouldn't replace a full-fledged admin section in my
case)
ASP.NET MVC supports scaffolding based on POCOs since second version. But it's not so quick'n'dirty solution.
Possibly some querying capabilities? Or can Raven indexes replace
virtually every SQL query I might think of?
You should to think about your queries first. Raven DB is not reporting database.
Entity Framework integration (I know some people hate EF but I think
that being an EF provider means that you can easily publish the data
as OData, use EF code-first etc., right?)
You are so focused on tools. Code First is the way how you work with document databases. Why you need OData? RavenDB has REST API out of the box.
WCF RIA Services (Silverlight).
You'll need to do all that WCF plumbing work.
I am trying to create a Family Tree website (for personal use) using MVC3 and SQL Server 2008 however I am relativly new to MVC3 (Using Razor & Entity Framework) but know SQL Server quite well.
I am getting quite frustrated and am tempted to develop the website using WebForms as I am very familiar with this tech.
My question is I am split between the following two approaches but am stuck on how to implement either using MVC3 and Entity Framework:
1) using a Person table containing information about an individual and a bridging table to store relationships between individuals held on the Person table.
2) Nested Sets storing all information on one table.
Can someone please, please give me some direction on how I can get started, preferably using the Nested Sets approach as I would like the performance of reading the hierarchy to be as quick as possible as this will be the main purpose of the site.
I hope I have provided enough information, if not please ask me for more details.
The way you organize your data in the data store has very little to do with MVC. All the data access is abstracted in the M part (the model) and how it is implemented in the back end does not matter, the model layer can be different but still present the same layer to the controler (the C part.)
This is exactly the reason for using a system like MVC. You could (for example) implement an MVC web site using MS SQL and then at a later time move to Oracle. The only code which would need to change is the code in the Model. MVC allows for separation of concerns.
So, to answer your question: Implement the SQL design in the way you think will work best. Then when the Model is written it will be "translated" to an interface needed for the controllers and the view.
Coda - I personally think it is easier to implement this data using more than one table, I think it makes the queries clearer. Your mileage may vary.
I have a project for a class which requires that if a database is used, options exist for the user to pick a database to use which could be of a different type. So while I can use e.g. MySQL for development, in the final version of the project, the user must be able to choose a database (Oracle, MySQL, SQLite, etc.) upon installation. What's the easiest way to go about this, if there is an easy way?
The language used is up to me as long as it's supported by the department's Linux machines, so it could be Java, PHP, Perl, etc. I've been researching and found info on ODBC, JDBC, and SQLJ (such as this) but I'm quite new to databases so I'm having a hard time figuring out what would be best for my needs. It's also possible there may not be a simple enough way to do this; the professor admitted he's not a database guy either and he seemed to think it would be easy without having a clear idea of what it would take.
This is for a web app, but it ought to be fairly straight forward, using for example HTML and Javascript on the client side and Java with a MySQL database on the server side. No mention has been made of frameworks so I think they're too much. I have the option of using Tomcat or Apache if necessary but the overall idea is to keep things simple, and everything used should be able to be installed/changed/configured with just user level access. So something like having to recompile PHP to use ODBC would be out, I think.
Within these limitations, what would be the best way (if any) to be able to interact with an arbitrary database?
The issue I think you will have here is that SQL is not truely standard. What I mean is that vendors (Oracle, MySQL etc) have included types and features that are not SQL standard in order to "tie you in" to their DB, such as Oracle's VARCHAR2 and so on.
When I was at university, my final year project was to create an application that allowed users to create relational databases using JDBC with a Java front-end.
The use of JDBC was very simple but the issue was finding enough SQL features/types that all the vendors have in common. So they could switch between them without any issues. A way round this is to implement modules to deal with vendor specific issues and write ways to translate between them. So for example you may develop a database for MySQL with lots of MySQL specific code in that, but then you may want to use Oracle and then there are issues, which you would need to resolve.
I would spend some time looking at what core SQL standard all the vendors implement and then code for these features. But I think the technology you use wouldn't be the issue but rather the SQL you create.
Hope this helps, apologies if its not helpful!
Well, you can go two ways (in Java):
You can develop your own classes to work with different databases and load their drivers in JDBC. This way you will create a data access layer for yourself, which takes some time.
You can use Hibernate (or other ORMs). This way Hibernate will take care of things for you and you only have to know how to use Hibernate. Learning Hibernate may take some time, but when you get used to it, it can be very useful for your future projects.
If you want to stick Java there Hibernate (which wouldn't require a framework). Hibernate is fairly easy to use. You write HQL which gets translated to the SQL needed for the database you're using.
Maybe use an object relational mapper (ORM) or database abstraction layer (DAL). They are designed to provide a standard API to multiple database backends, making it possible to switch between different backends with minimal or no changes to your code. In Python, for example, a popular ORM is SQLAlchemy, and an excellent DAL is the web2py DAL (it's part of the web2py framework but can be used as a standalone DAL outside the framework as well). There are many other options in other languages as well.
use a framework with database abstraction layer and orm . try symfony or rails
There are a lot of Object relational database frameworks, unless you prefer jdbc. For simple/small applications this should work fine.
I am doing something I consider to be pretty normal (although I personally haven't had to do it before), and I have assumed there'd be a 'no-brainer' way forward, but Im yet to find it - which is really frustrating.
I will be creating a WPF application, which is a data-oriented business application. My data will come from a remote IIS server (that I control) that has a standard SQL server 2008 database, so Web services/WCF seem to be the way forward. The remote service needs to be secure (reasonably) via a user (of the WPF client) username/password login.
I dont want to use 3rd party ORM products, but I expect the data layer (between the service and the database) to be able to cope with very simple ORM type functionality (I really dont want to hand-craft a data retrieval and persistence layer). Im not worried about concurrency very much as this will be a fairly simple app.
My options seem to be one of the following:
ADO.NET Entity Framework over WCF
Linq2Sql over WCF
WCF Data Services
On further investigation, none of the above seem to be the 'no brainer' Im after
1) ADO.NET entity Framework - Ive had a play with this and getting all sorts of issues serializing objects over WCF. Even when I try to generate POCO entities and use them, Im having to decorate service contracts with custom attributes just to get it to not error all the time, and I seem to have to hand-crank anything more than a flat object graph. It seems to me that EF simply isn't designed to be exposed via a service.
2) Linq2Sql - This doesn't seem much better than EF. I seem to have to hand-crank too much stuff. Ive tried the designer and SQLMetal but nothing seems to 'just work' - it all needs fiddling with.
3) WCF Data Services - this seems like a good option on the face of it, but essentially it seems like I'm just exposing my SQL database tables 'in the raw' over the service layer. Im not an expert in this technology by any means but it seems like a potentially dangerous approach, and on top of that it doesnt seem to support any kind of access security as standard (you have to hack it to require authentication it seems).
As I said, this scenario feels like it should have a no-brainer solution, but Im still scratching my head. Ive done lots of things with .NET technologies, but to be honest this area represents a bit of a hole in my understanding, so I apologize if any of my comments or assumptions are naive.
Of course, it may well be that the 'hacky' long-way-round on EF or Linq2SQL may be all I can do, in which case I can roll up my sleeves, and accept the fact that I haven't missed a more elegant solution.
Any help/advice will be much appreciated.
This is a tad subjective, but i'll offer my opinion.
First of all, forget L2SQL - it's basically obsolete and doesn't have the full POCO support of EF4 (it can be done, but needs XML tinkering, or SQLMetal generation), which means serializaing your entities will be a left-to-right entity cloning nightmare.
I would go with ADO.NET Entity Framework over WCF, Entity Framework 4.0 specifically. You will have a wealth of flexibility in your model (including the ability to apply OO principles such as inheritance).
Use Self-Tracking-Entities. Yes, you have to decorate service contracts - this is by design, and there are many reasons for this.
You could always use DTO's, as opposed to serializing the actual EF entities.
OData is really good as well in it's flexibility and simplicity. But if your only consuming your model via a single client application, a specialized service layer (WCF) is a better approach IMO.
3) WCF Data Services - this seems like
a good option on the face of it, but
essentially it seems like I'm just
exposing my SQL database tables 'in
the raw' over the service layer.
That might be a first impression - but it's fundamentally wrong. What you're exposing over the web is a model - and you have full control over what gets into that model, and how consumers of your WCF Data Services might be able to see and/or even update entities in that model.
That's where Entity Framework comes in and shines (and where Linq-to-SQL miserably fails): you can grab your database (or at least parts of it) into an Entity Data Model, and then modify it. You can tweak your entity names to be totally different from your table names, you can add computed attributes, you can remove certain attributes and much more.
If you're talking about a fairly simple app, that's definitely the way I'd go:
grab your database and turn it into an Entity Data Model using EF
expose that EDM over WCF Data Services and define what can be seen read-only, and what might even be updated over the wire
We have a new django powered project which have a potential heavy-traffic characteristic(means a heavy db interaction). So we need to consider the database scalability in advance. With some researches, the following questions are still not clear to us:
coarse-grained: how to specify one db table(a django model) to a specific db(maybe in another server)?
fine-grained: how to specify a group of table rows to a specific db(so-called sharding, also can in another db server)?
how to specify write and read to different db?(which will be helpful for future mysql master/slave replication)
We are finding the solution with:
be transparent to application program(means we don't need to have additional codes in views.py)
should be in ORM level(means only needs to specify in models.py)
compatible with the current(or future) django release(to keep a minimal change for future's upgrading of django)
I'm still doing the research. And will share in this thread later if I've got some fruits.
Hope anyone with the experience can answer. Thanks.
Don't forget about caching either. Using memcached to relieve your DB of load is key to building a high performance site.
As alex said, django-core doesn't support your specific requests for those features, though they are definitely on the todo list.
If you don't do this in the application layer, you're basically asking for performance trouble. There aren't any really good open source automation layers for this sort of task, since it tends to break SQL axioms. If you're really concerned about it, you should be coding the entire application for it, not simply hoping that your ORM will take care of it.
There is the GSoC project by Alex Gaynor that in future will allow to use multiple databases in one Django project. But now there is no cross-RDBMS working solution.
There is no solution right now too.
And again - there is no cross-RDBMS solution. But if you are using MySQL you can try excellent third-party Django application called - mysql_replicated. It allows to setup master-slave replication scenario easily.
here for some reason we r using django with sqlalchemy. maybe combination of django and sqlalchemy also works for your needs.