I have found many samples and examples of silverlight applications that use EF for their data store. Why is it that every single one uses a database full of data and shows how to edit/save? I'm having problems setting up an application where I (want to) have no data to start with and would like my user to then populate the data store. Everything works fine when data exists but I get into all sorts of null problems when I want to start with no data.
Just saying...
ANyway, my question: Does anyone know of any tutorials that demonstrate code where no data yet exists?
Thanks!
(Sorry for my bad english)
I suppose you are using RIA Services? That's the easiest way to develop an SL app with EF. It should make no diference between having data or not, the RIA Service returns a collection with 0 or more itens, you bind that with a DataGrid and are done. Here is a link with source code of a full aplication, that starts with no data: http://johnpapa.net/wcf-ria-services-hands-on-lab - What is most important to understand is the asynchronous nature of RIA Services. Keep that in mind, take a look and try the code.
If you have more questions, try to be more specific about the exact errors or problems you are facing, it would be easy to others try to help you :)
Related
So I am looking to freshen up my dev skills. I come from a classic ASP background using VB, so this new .net and Model concept is very foreign to me. I cant seem to get my head wrapped around it yet. I have tried going through the tutorials, but most are C# and I plan to use VB.net.
My needs at the moment are very simple (or at least i thought they were) Does anyone have a simple example or explanation of how I can create a simple page that pulls data from a local SQL Express DB?
I understand how the Controllers and Views work(mostly), but the Models just make zero sense to me
I created a new Model for a very simple database called Test. It has only 5 columns. (Username, Password, Email_Address, Text_number, and UserID (UID). It created a Model1.edmx, but that's it. Nothing else below it. Where the heck do I go from here?
Uggghhh I feel so dumb!! I used to be OK at this, now it's SOOO different!! I miss my T-SQL, Recordsets, and Loops.
If you want db first you should create a new .edmx Model using "generate from database".
When you have created an .edmx model then you usually create your Entity Classes (see tutorials below) with the "add code generation item". You can read about this in one of the linked tutorials, under "Generating Strongly Typed Entity Classes". After that you're ready to go the controller and create your first query to return some data.
I suggest you start watching these free tutorials about MVC3/4, even if they are in C# and you want to use vb.net, I'm sure you can easily understand what's going on since it's clearly explained
http://www.asp.net/mvc/pluralsight
also read these tutorials that show database first approaches
http://msdn.microsoft.com/en-US/data/jj206878
http://msdn.microsoft.com/en-us/data/gg685489.aspx - VB.net project
To connect to your database, you might want to consider an ORM, like one of the following:
Entity Framework
NHibernate
Linq2Sql (built-in/already installed)
Each of these are very popular and make it easy to quickly snap a code-wrapper around your DB. Then, in your model, you use the ORM objects(wrapping your DB) to call through to the DB.
I'll try to explain as briefly as possible:
C#.Windows application for categories and descriptions of files.
Windows Forms - for the user
A library I want to be saved for future usage - I got nice algorithms for tasks with XML,Files,strings. In this case they are to serve the WF, but i don't want to keep them in the Form classes. I want to have them as a separate library with namespaces and classes in it. But I don't know what type of project or addition to the whole VS "Solution" that has to be.
Windows Service - get notifications on file changes and updates the same db the WF is using.
LINQ to SQL - for the data access
WCF - I am just throwing that here, because it seems that I need to use it(answer from a previous related topic) : https://stackoverflow.com/a/15998122/1356685
SO...yeah...architecture, architecture. Any guideline for a good architecture in my case is welcomed. Now I know in these conversations people start throwing terms like: "business logic","persistence layer","model layer" and what not. However I don't quite understand them, so please be specific.
Thanks in advance for the help !
Microsoft has a pretty extensive application architecture guide and their patterns and practices website has a lot of information and code samples showing you how to structure applications.
As for your 'library to be saved for future usage'... you can create a C# Class Library project and add it as a Reference in whatever applications you'd like to use it in.
Thanks in advance for any help offered and patience for my current web-coding experience.
Background:
I'm currently attempting to develop an web based application for my family's business. There is a current version of this system I have developed in C#, however I want to get the system web-based and in the process learn cakephp and the MVC pattern.
Current problem:
I'm currently stuck in a controller that's supposed to take care of a PurchaseTicket. This ticket will have an associated customer, line items, totals etc. I've been trying to develop a basic 'add()' function to the controller however I'm having trouble with the following:
I'm creating a view with everything on it: a button for searching customer, a button to add line items, and a save button. Since I'm used to developing desktop applications, I'm thinking that I might be trying to transfer the same logic to web-based. Is this something that would be recommended or do'able?
I'm running into basic problems like 'searching customer'. From the New Ticket page I'm redirecting to the customer controller, searching and then putting result in session variable or posting it back, but as I continue my process with the rest of the required information, I'm ending up with a bit of "spaghetti" code. Should I do a multi part form? If I do I break the visual design of the application.
Right now I ended up instantiating my PurchaseTicket model and putting it in a session variable. I did this to save intermediate data however I'm not sure if instantiating a Model is conforming to cakephp standards or MVC pattern.
I apologize for the length, this is my first post as a member.
Thanks!
Welcome to Stack Overflow!
So it sounds like there's a few questions, all with pretty open-ended answers. I don't know if this will end up an answer as such, but it's more information than I could put in a comment, so here I go:
First and foremost, if you haven't already, I'd recommend doing the CakePHP Blog Tutorial to get familiar with Cake, before diving straight into a conversion of your existing desktop app.
Second, get familiar with CakePHP's bake console. It will save you a LOT of time if you use it to get started on the web version of your app.
I can't stress how important it is to get a decent grasp of MVC and CakePHP on a small project before trying to tackle something substantial.
Third, the UI for web apps is definitely different to desktop apps. In the case of CakePHP, nothing is 'running' permanently on the server. The entire CakePHP framework gets instantiated, and dies, with every single page request to the server. That can be a tricky concept when transitioning from desktop apps, where everything is stored in memory, and instances of objects can exist for as long as you want them to. With desktop apps, it's easier to have a user go and do another task (like searching for a customer), and then send the result back to the calling object, the instance of which will still exist. As you've found out, if you try and mimic this functionality in a web app by storing too much information in sessions, you'll quickly end up with spaghetti code.
You can use AJAX (google it if you don't already know about it) to update parts of a page only, and get a more streamlined UI, which it sounds like something you'll be needing to do. To get a general idea of the possibilities, you might want to take a look at Bamboo Invoice. It's not built with CakePHP, but it's built with CodeIgniter, which is another open source PHP MVC framework. It sounds like Bamboo Invoice has quite a few similar functionalities to what you're describing (an Invoice has line items, totals, a customer, etc), so it might help you to get an idea of how you should structure your interface - and if you want to dig into the source code, how you can achieve some of the things you want to do.
Bamboo Invoice uses Ajax to give the app a feel of 'one view with everything on it', which it sounds like you want.
Fourth, regarding the specific case of your Customer Search situation, storing stuff in a session variable probably isn't the way to go. You may well want to use an autocomplete field, which sends an Ajax request to server after each time a character is entered in the field, and displays the list list of suggestions / matching customers that the server sends back. See an example here: http://jqueryui.com/autocomplete/. Implementing an autocomplete isn't totally straight forward, but there should be plenty of examples and tutorials all over the web.
Lastly, I obviously don't know what your business does, but have you looked into existing software that might work for you, before building your own? There's a lot of great, flexible web-based solutions, at very reasonable prices, for a LOT of the common tasks that businesses have. There might be something that gives you great results for much less time and money than it costs to build your own solution.
Either way, good luck, and enjoy CakePHP!
Could some explain how to best organize the model entity classes in GWT for use on app engine?
I have been using this ebook as an example to follow http://code.google.com/p/gwt-gae-book/wiki/StoringData, but I am unsure about where to add this code. I do not need help in how to write the classes, I just want to know does this code go in the client or server?
In my application I have one module that handles the UI and that is it so far. My next step is implementing the data functionality features.
I also plan on using twig and appwrench, if possible, in developing my model if that helps.
Thanks in advance for any help in getting this setup.
Am assuming you are new to programming and hence detailed explanation for you:
Everything else except for UI and RPC calls to server will reside in "server" package. Within server side code, you would further like to create modules which interact with each other. Like the layer which receives calls from client and processes them. Another layer which contains core business logic, and next layer which interacts with DB, where your entities/model will reside.
You can look at example for your current problem which separates various layers of code. Only difference being the code is using JSP for it's UI.
I'm asking for the advice. I'm working at the Silverlight 3 application and now I should select the mean how to save the information and get it. I could save the necessary info in files (from 1 to 300K size) or I could save them in database. If I would use WebClient for accessing to separate file there's very low loading of the server. If I get data from database the server would load much more I think and the code on the server too.
Please correct me if I'm not right.
I'm looking forward to hearing from you!
Thanks
there are additional considerations if you use a file that is localized to the users machine. If you wish to save data w/o any user intervention then you are limited to using Isolated Storage, which has constraints on the size of your data. Otherwise, you have to ask the user for information on where to save/load the file. This is due to the security model used by silverlight.
i am thinking that a Database and the RIA framework might be the way to go.
just my 2ยข
If you are saving and loading the entire file at a time, then it might be okay to use a WebClient. This might take a little coding to handle errors that may result in incomplete saves.
If you're serializing some objects or xml data and storing that in a file, then you should probably be using a database instead.
Edit: It can be a pain to get WebClient or HttpWebRequest working correctly with GET/POST, but WCF can also be a pain to configure if you haven't done it before. WCF is probably better style, and you'll want to use a binary binding and send the file across as a byte[].