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Posts tagged CriteriaBuilder
Criteria Builder Quickie: Disjunction
Mar 12th
If you use ColdBox’s awesome CriteriaBuilder at all, you know it’s dead simple to create complex AND dynamic criteria queries. If you’re like me, a lot of your criteria queries are a bunch of “and”s built together. For example, let’s imagine we’re trying to get all the cars from our database that have a make of Ford and a color of Red. A simple criteria query for this might look like:
// create criteria
var c = newCriteria();
// add criteria
c.isEq( "Make", "Ford" )
.isEq( "Color", "Red" );
// get result
var result = c.list();
Pretty simple, right?
Of course, not all queries are “and“s. Sometimes, you need to do an “or“. Perhaps we want to get all the cars that are Ford OR Red. Again, this is very easy with CriteriaBuilder:
// create criteria
var c = newCriteria();
// add criteria
c.or(
c.restrictions.isEq( "Make", "Ford" ),
c.restrictions.isEq( "Color", "Red" )
);
// get result
var result = c.list();
While this works, it’s not complete. Sure, there are some scenarios where you will know ahead of time what criteria you want to use in a criteria query. However, consider a scenario in which you have a search form in which a user can select from a list More >
Custom SQL Projections in CriteriaBuilder
Aug 25th
In my last post, I showed how you can pretty easily integrate ColdBox’s awesome CriteriaBuilder with subqueries. As I was using this approach, I came across another (unrelated) challenge that I wanted a solution for.
Simple Grouping/SummingIn one of my queries, I wanted to do some simple grouping/summing. With CriteriaBuilder, you can do this very easily by adding a projection or two.
For example, let’s imagine that we have the same entities as before:
- Car
- Driver
- Insurance
This time, we want to get a sum of the total number of cars, grouped by “make”. Easy:
public struct function getCarsByMake() {
var c = newCriteria();
c.withProjections( count="CarID", groupProperty="Make" );
var results = {
data = c.list()
};
results.count = arrayLen( results.data );
return results;
}
And the SQL:
select this_.Make as y0_, count(this_.CarID) as y1_ from Car this_ group by this_.Make
Pretty simple. By the application of the “count” and “groupProperty” projections, we get back a nice array of the grouped data. Note, of course, that because of the application of projections, our result set is no longer in the domain of discreet entities. Rather, since we asked for aggregate data, that’s what we get! Of course, this means that results.count has to be calculated differently. Instead of running CriteriaBuilder’s count() method More >
Subqueries with ColdBox CriteriaBuilder
Aug 20th
Here is the code on GitHub, if you want it.
Over the last several months, I’ve been working heavily in a brand-new environment (to me): one that is built upon ColdBox and leverages all of the awesome goodies that ColdBox provides in the way of rapidly and easily developing ORM-driven applications. If you spend more than 3 minutes in a ColdBox ORM app, you’ll quickly come to rely upon–and LOVE–ColdBox’s CriteriaBuilder, which lets you easily build intensely complicated HIbernate criteria queries…without the nonsense of string concatenation.
The other day, however, I ran into a bit of a wall. Before I explain the issue, let me give a quick summary of the context.
In my app, I have a good number of concrete services that extend the uber-handy Virtual Entity Services. Since my app is driven largely by an AJAX frontend, there are lots of cases in which I not only want to return a JSON-representation of a result set, but also important meta-data about the result set (e.g., total record count for paging, etc.). Obviously, since I want that bundled into one single response, I have lots of methods that do something like so in one of my concrete services:
function getResults( event, rc, prc More >
