I have two Sencha/ExtJS4 grids which use the exact same data (ie, same store.proxy.url), but each uses different filters, so each has its own separate store. The problem is I am making an unnecessary AJAX call to retrieve the extra copy to work with.
What is the recommended approach to make a single AJAX call and then share the data between two stores, for independent filtering?
potential solutions:
create two classes that extend the same store ?
use the same proxy instance ?
retrieve one store then cloning it ?
The Ext JS 4 framework seems to be built with the intention that each view receives its own store. As mentioned in other answers, your best option is to create a second store and copy all the records from one to the other.
function cloneStore(src, dest) {
var recs = src.getRange(); // returns array of records
dest.loadRecords(recs); // removes existing records before batch add
}
The exact implementation of that function may vary depending on how you need your data spread out. If each grid only needs a subset of the data to begin with, you can initialize a master store from your Ajax call, then create two sub-stores using filters directly on the store.data MixedCollection.
// Note: This function isn't exactly "good practice"
// Actual implementation may vary
function populateSubStores(master, storeA, storeB) {
var dataA = master.data.filter(/* filter criteria for store A */),
dataB = master.data.filter(/* filter criteria for store B */);
// dataA and dataB are MixedCollections of records
storeA.loadRecords(dataA.getRange());
storeB.loadRecords(dataB.getRange());
}
Or some variation thereof. This should be enough to get you started in the right direction.
If you're really gung-ho, you could create a new type of store that maintains separate MixedCollections representing filter states from different views, then return each filter state as a store with an identical interface to Ext.data.Store but with an implementation that operates on the "master" store's internal representation so that existing views can operate without overrides. But I don't recommend it.
You can create two instances of one store and then just copy data from one store to another using getRange() and add() methods. Creating two classes doesn't seem reasonable.
Related
While working with a ViewModel and a List stored in there, I usually followed this approach:
var characteristics by mutableStateOf(listOf<Characteristic>())
Then, I could assign data to the List or modify it, and the UI would recompose properly:
characteristics = issuesRepository.getCharacteristics()
characteristics = characteristics.plus(newCharacteristic)
However, I recently stumbled across several approaches containing the keyword mutableStateListOf(), and it then seems to be a common practice to split a List into two separate variables, like this:
private val _characteristic = mutableStateListOf<Characteristic>()
val characteristic: List<Characteristic> = _characteristic
How do these approaches differ, and is one of those considered best-practice or as a cleaner approach?
Using mutableStateOf you are creating an observable object. So, the recomposition will happen just if you assign a new instance to this state.
Let's say that you want that recomposition happens after add a new item to the list. In this case, you need to create a copy of this list, add the elemento to this copied list, and then assign the copied list to the state.
The mutableStateListOf creates an observable list. All operations you've done in this list (add, remove, update) will cause a recomposition.
I would like to get some thoughts from others about the following problem.
Let's assume we have two classes Products and Items. Products object allows us to access any Item object. Here's the example.
$products = new Products();
// get existing item from products
$item = $products->get(123);
// create item
$item = $products->create();
$item->setName("Some new product");
$item->setPrice(2.50);
Now what would be the best way to update/save state of the item? I see 2 options:
$item->save();
or
$products->save($item);
First aproach seems very straigh forward. Once attributes of Item object are set calling save method on it will persist changes.
On the other hand I feel like latter approach is better. We're separating the roles of two objects. Item object contains only state and Products object operates on that state. This solution may be also better for writing unit tests.
Any thoughts?
So, effectively the items are buffering the actual changes.
Clearly both approaches will work, however it comes down to how closely you want to adhere to the underlying database's model or the overlaid object model.
Viewed from the outside, $item->save() makes the most sense in terms of the model - as you point out, you update the item's properties and then save them down. Plus it is conceptually an action that is performed on the item.
However, $products->save($item) offers two noticable advantages, and a drawback.
On the plus side, by moving save into products, it can (potentially) handle batching / reordering of the updates in a smarter way since it has visibility of all the items. It also allows the save code to be used as ->add() (more or less)
A downside is it is going to (from the object model view) add the following possible use, which you probably don't want:
$p1 = new Products();
$p2 = new Products();
$item = $p1->create();
// set $item values
$p2->save($item);
Obviously, you could just add an 'is this mine? no? then throw an error' test to Products::save, but that is extra code for blocking a use case the syntax implies could/should work. Or at least would probably slip through a code review.
So, I'd say go with the approach that seems the simplest and binds tightest to the desired functionality ($item->save()), unless you need to do caching/batching/whatever that forces you to go with the other.
Currently I am working partly with cfwheels and its Active Record ORM (which is great), and partly raw cfml with its Hibernate ORM (which is also great).
Both work well for applicable situations, but the thing I do miss most when using CF ORM is the model.update() method that is available in cfwheels, where you can just pass a form struct to the method, and it will map up the struct elements with the model properties and update the records.. really good for updating and maintaining large tables. In CF ORM, it seems the only way to to update a record is to set each column individually, then do a save. Is this the case?
Does cf9 ORM have an Active Record type update() (or equivalent) method which can just receive a struct with values to update and update the object without having to specify each one?
For example, instead of current:
member = entityLoadByPK('member',arguments.id);
member.setName(arguments.name);
member.setEmail(arguments.email);
is there a way to do something like this in CF ORM?
member = entityLoadByPK('member',arguments.id);
member.update(arguments);
Many thanks in advance
In my apps I usually create two helper functions for models which handle the task:
/*
* Get properties as key-value structure
* #limit Limit output to listed properties
*/
public struct function getMemento(string limit = "") {
local.props = {};
for (local.key in variables) {
if (isSimpleValue(variables[local.key]) AND (arguments.limit EQ "" OR ListFind(arguments.limit, local.key))) {
local.props[local.key] = variables[local.key];
}
}
return local.props;
}
/*
* Populate the model with given properties collection
* #props Properties collection
*/
public void function setMemento(required struct props) {
for (local.key in arguments.props) {
variables[local.key] = arguments.props[local.key];
}
}
For better security of setMemento it is possible to check existence of local.key in variables scope, but this will skip nullable properties.
So you can make myObject.setMemento(dataAsStruct); and then save it.
There's not a method exactly like the one you want, but EntityNew() does take an optional struct as a second argument, which will set the object's properties, although depending on how your code currently works, it may be clunky to use this method and I don;t know whether it'll have any bearing on whether a create/update is executed when you flush the ORM session.
If your ORM entities inherit form a master CFC, then you could add a method there. Alternatively, you could write one as a function and mix it into your objects.
I'm sure you're aware, but that update() feature can be a source of security problems (known as the mass assignment problem) if used with unsanitized user input (such as the raw FORM scope).
I have to add a bunch of trivial or seldom used attributes to an object in my business model.
So, imagine class Foo which has a bunch of standard information such as Price, Color, Weight, Length. Now, I need to add a bunch of attributes to Foo that are rarely deviating from the norm and rarely used (in the scope of the entire domain). So, Foo.DisplayWhenConditionIsX is true for 95% of instances; likewise, Foo.ShowPriceWhenConditionIsY is almost always true, and Foo.PriceWhenViewedByZ has the same value as Foo.Price most of the time.
It just smells wrong to me to add a dozen fields like this to both my class and database table. However, I don't know that wrapping these new fields into their own FooDisplayAttributes class makes sense. That feels like adding complexity to my DAL and BLL for little gain other than a smaller object. Any recommendations?
Try setting up a separate storage class/struct for the rarely used fields and hold it as a single field, say "rarelyUsedFields" (for example, it will be a pointer in C++ and a reference in Java - you don't mention your language.)
Have setters/getters for these fields on your class. Setters will check if the value is not the same as default and lazily initialize rarelyUsedFields, then set the respective field value (say, rarelyUsedFields.DisplayWhenConditionIsX = false). Getters they will read the rarelyUsedFields value and return default values (true for DisplayWhenConditionIsX and so on) if it is NULL, otherwise return rarelyUsedFields.DisplayWhenConditionIsX.
This approach is used quite often, see WebKit's Node.h as an example (and its focused() method.)
Abstraction makes your question a bit hard to understand, but I would suggest using custom getters such as Foo.getPrice() and Foo.getSpecialPrice().
The first one would simply return the attribute, while the second would perform operations on it first.
This is only possible if there is a way to calculate the "seldom used version" from the original attribute value, but in most common cases this would be possible, providing you can access data from another object storing parameters, such as FooShop.getCurrentDiscount().
The problem I see is more about the Foo object having side effects.
In your example, I see two features : display and price.
I would build one or many Displayer (who knows how to display) and make the price a component object, with a list of internal price modificators.
Note all this is relevant only if your Foo objects are called by numerous clients.
I don't know much about Dojo but is the following possible:
I assume it has a getter/setter for access to its datastore, is it possible to override this code.
For example:
In the dojo store i have 'Name: #Joe'
is it possible to check the get to:
get()
if name.firstChar = '#' then just
return 'Joe'
and:
set(var)
if name.firstChar = '#' then set to #+var
Is this sort of thing possible? or will i needs a wrapper API?
You can get the best doc from http://docs.dojocampus.org/dojo/data/api/Read
First, for getting the data from a store you have to use
getValue(item, "key")
I believe you can solve the problem the following way. It assumes you are using a ItemFileReadStore, you may use another one, just replace it.
dojo.require("dojo.data.ItemFileReadStore");
dojo.declare("MyStore", dojo.data.ItemFileReadStore, {
getValue:function(item, key){
var ret = this.inherited(arguments);
return ret.charAt(0)=="#" ? ret.substr(1) : ret;
}
})
And then just use "MyStore" instead of ItemFileReadStore (or whatever store you are using).
I just hacked out the code, didn't try it, but it should very well show the solution.
Good luck
Yes, I believe so. I think what you'll want to do is read this here and determine how, if it will work:
The following statement leads me to believe the answer is yes:
...
By requiring access to go through
store functions, the store can hide
the internal structure of the item.
This allows the item to remain in a
format that is most efficient for
representing the datatype for a
particular situation. For example, the
items could be XML DOM elements and,
in that case, the store would access
the values using DOM APIs when
store.getValue() is called.
As a second example, the item might be
a simple JavaScript structure and the
store can then access the values
through normal JavaScript accessor
notation. From the end-users
perspective, the access is exactly the
same: store.getValue(item,
"attribute"). This provides a
consistent look and feel to accessing
a variety of data types. This also
provides efficiency in accessing items
by reducing item load times by
avoiding conversion to a defined
internal format that all stores would
have to use.
...
Going through store accessor function
provides the possibility of
lazy-loading in of values as well as
lazy reference resolution.
http://www.dojotoolkit.org/book/dojo-book-0-9/part-3-programmatic-dijit-and-dojo/what-dojo-data/dojo-data-design
I'd love to give you an example but I think it's going to take a lot more investigation.