Building LINQ Queries at Runtime in C#

Since the first beta versions of LINQ we could hear comments that it is perfect for queries known at compile-time, however it is not possible to use it for building queries dynamically at runtime. In this article I show that this can be actually done very well for most of the common cases. The solution offered by Microsoft (mentioned in [1]) is to build query from a string, however this has many limitations and it in fact goes completely against what LINQ tries to achieve, which is writing queries in a type-safe way with full compile-time checking. In this article I will first show a few support functions to make the life a bit easier and then we will use them for building two sample applications that allows user to build a query dynamically. The solution is largely motivated by my previous use of F#, where working with “expressions” is possible at more advanced level, however I’ll write about F# later and now let’s get back to C# 3.0...

F# Web Tools: "Ajax" applications made simple

Traditional "Ajax" application consists of the server-side code and the client-side part written in JavaScript (the more dynamicity you want, the larger JS files you have to write), which exchanges some data with the server-side code using XmlHttpRequest, typically in JSON format. I think this approach has 3 main problems, which we tried to solve in F# Web Toolkit. There are a few projects that try to solve some of them already - the most interesting projects are Volta from Microsoft [1], Links language [3] from the University of Edinburgh and Google Web Toolkit [2], but none of the projects solve all three problems at once.

1. Limited client-side environment
2. Discontinuity between server and client side
3. Components in web frameworks are only server-side

The aim of the F# Web Toolkit is to solve all these three problems...

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