ComboBox: server-side filtering of the options?

[AdrianVasiliu]

Currently, ComboBox implements the (optional) filtering the options using a filter function executed client-side.

What about server-side filtering, or at least a mechanism allowing the user to implement it?
Requires investigation.

As a side note related with filtering, it might be nice that, if no item matches the query thus the list is empty, the popup shows some specific graphic feedback (to be defined).

[wkeese]

I thought ComboBox filtered the options by setting the List's query property, and then List requeries the store. Doesn't that query evaluate on the server automatically, assuming you have a client/server store?

[AdrianVasiliu]

It does set List's query property, which triggers delite/Store.computeProperties() which triggers a query on the data store. But it does so (for now) using a filter function:

this.list.query = function (obj) {
    return this._filterFunction(obj[this.list.labelAttr], txt);
}.bind(this);
_filterFunction: function (itemLabel, queryTxt) {
    // TODO: options for case-sensitiveness, startsWith/contains
    // TODO: check fancy locale support...
    queryTxt = queryTxt.toLocaleUpperCase();
    itemLabel = itemLabel.toLocaleUpperCase();
    return itemLabel.indexOf(queryTxt) === 0;
},

https://github.com/ibm-js/deliteful/blob/master/ComboBox.js#L308

The filtering mechanism has been reworked quite a lot in dstore wrt. dojo/store. Since July, dstore has introduced a dstore/Filter API:
https://github.com/SitePen/dstore/blob/v0.2.0/docs/Collection.md#filtering,
https://github.com/SitePen/dstore/blob/v0.2.0/Filter.js

The subject seems still "alive", see dojo/dojo1-dstore#44 or dojo/dojo1-dstore#34.

This might be already the way to go, but whether this is working well for server-side filtering it needs to be checked. The purpose of this issue is precisely to investigate what's the best we can do.

[cjolif]

dstore/Filter is "just" a way to easily build a filter object. For your case you should probably do something like the following (using regexp):

var filter = new Filter();
list.query = filter.match("label", /abc/);

This will work as-is with dstore/Memory and should work with dstore/Rest if the server is correctly implementing the filtering.

[AdrianVasiliu]

Yes. Now, the require of dstore modules has been removed recently from our widgets (Combobox, List). To use the Filter API we'd need to put back a dependency on dstore (for the Filter module itself).

[cjolif]

Right. An alternate approach is to generate yourself the object that is generated by Filter, Filter is after all just a utility. It should generate something like the following (to be double checked):

list.query = { type: "and", args: ["label", /abc/] }

[AdrianVasiliu]

An alternate approach is to generate yourself the object that is generated by Filter,

As we have seen, this does not seem to do the trick. Hence the use of dstore/Filter in 24e5f71.