The Problem
Imagine that you have a one-to-many relationship in your database, for example, you have table person in which you keep personal data (first, middle, last names, etc.) and you have table phone where you keep phone numbers (phone type, phone number).
It is quite common to have person:phones, company:phones, order:items, invoice:items, etc relationships, isn’t it?
Now, it is quite easy to create a grid that displays list of persons but what about their phones? They are in the different table. Yes, we could create two stores: one for persons grid and another, hidden, for phones, load them from server and somehow filter phones depending on persons.
Nevertheless, I was looking for a simpler solution as I wanted one client server round trip and I wanted to display “many” data in QuickTip. And I found one…
Solution – Server Side
MySql, that I use as my main database backend, has function group_concat since version 4.1 and SQLite has it since version 3.5.
The idea is to join tables person and phone server side and return “many” data in one extra field as string separated by arbitrary separators. The SQL statement would be as follows:
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select persFirstName, persMidName, persLastName, group_concat(concat_ws('~', phoneType, phoneNumber), '|') as phones from person left join phone on person.persID=phone.persIDs group by person.persID |
phones part of the output of the above sql would look like
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Home~123456|Work~87654|Mobile~654321 |
Solution – Client Side
We cannot display received phones directly in person grid (well we could but users would hate us) but we need some processing. I decided to display phones in QuickTips so I needed custom renderer for persLastName:
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/** * Last Name rederer including tooltip with phones * @param {Mixed} val Value to render * @param {Object} cell * @param {Ext.data.Record} record */ ,renderLastName:function(val, cell, record) { // get data var data = record.data; // convert phones to array (only once) data.phones = Ext.isArray(data.phones) ? data.phones : this.getPhones(data.phones); // create tooltip var qtip = this.qtipTpl.apply(data.phones); // return markup return ' |
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'; } // eo function renderLastName |
and getPhones function:
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/** * Converts string phones to array of objects * @param {String} phones * @return {Array} Array of phone objects */ ,getPhones:function(phones) { // empty array if nothing to do if(!phones) { return []; } // init return value var retval = []; // split string to phones var aps = phones.split('|'); // iterate through phones to extract phoneType and phoneNumber Ext.each(aps, function(phone) { var a = phone.split('~'); retval.push({phoneType:a[0], phoneNumber:a[1]}); }); return retval; } // eo function getPhones |
A bit of XTemplate work for QuickTips and we’re done.
Conclusion
This is not full fledged one-to-many data handling with editing, adding and deleting items at “many” side, it is just simple display of data from “many” table, anyway, it can come handy sometimes.
You can see the working example here: http://examples.learnfromsaki.com
The “many” display target does not need to be QuickTip, it can be row expander as well.
saki
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Wow I had never heard of group_concat, so I have learned something new today! Thanks for the great article!
Saki, if you don’t mind, a database question. Do you use your application or the database to enforce relationships between tables? Meaning if you have mysql tables that would have foreign keys in other tables, etc. do you let the database handle the on cascade stuff to enforce the table relations when records are added/deleted, or do you enforce this with your application/php logic? I’m not sure which way to go with this and wanted your wisdom on the matter.
MJ.
Yes MJ,
I use relationships of InnoDB Engine of mySQL. I always use ON UPDATE CASCADE and selectively, when appropriate, ON DELETE CASCADE.
Of course, PHP and/or Ext have to take into account these relationships, e.g. Ext has to supply parent ID when updating child record but mySQL takes additional care about data integrity.
Cheers,
Saki
Hi Saki,
Nice work. I was wondering if you have ever used Perl with EXTJS? The work that I do does not allow me to use PHP. Although I do use it for other projects. I am interested in seeing some examples of how Perl could be used with EXTJS in conjunction with JSON.
Any thoughts?
Hi Jeff,
no I don’t use Perl but I think that it wouldn’t be too different. I believe that there has to be some good JSON encode/decode in Perl so it boils down to find one.
I would first search rpms of your distribution (assuming you are using Linux on your server) and second, I would google for it.
Cheers,
Saki
Hi, Saki,
Cool, but i found a question. It will display “[object Object]” when sort columns. Is it a bug?
What do you think?
@James, it seem to be, however, it doesn’t invalidate the idea. Just some more logic is needed.
Hi Saki,
I have to implement this with extjs 4.0.2 but couldnt found the code working with it.
Can you please suggest if any more changes need to be done.
Thanks,
Vikas Kapoor
Hi Saki,
I am new to ExtJs. I am trying to build a treepanel where my store uses a json file for data.
Json file goes like this,
{
“data”: [
{
“id”: “1”,
“title”: “All”,
},
{
“id”: “2”,
“title”: “Actors/Actresses”,
},
{
“id”: “3”,
“parentId”: “2”,
“leaf”: true,
“title”: “Actors”
},
{
“id”: “4”,
“parentId”: “2”,
“leaf”: true,
“title”: “Actresses”
},
{
“id”: “9”,
“title”: “Favorites”
},
{
“id”: “10”,
“parentId”: “9”,
“leaf”: true,
“title”: “Favorite Actors”
},
{
“id”: “12”,
“parentId”: “9”,
“leaf”: true,
“title”: “Favorite Actresses”
},
{
“id”: “21”,
“title”: “Cast By”
},
{
“id”: “22.94”,
“parentId”: “21”,
“title”: “Administrators”
},
{
“id”: “23.94.4”,
“parentId”: “22.94”,
“userTitle”: {
“id”: 4,
“firstName”: “Chan”,
“lastName”: “Bairy”,
“email”: “chandrakanth.bairy@gmail.com”,
“jobTitle”: “Dev”
}
}
]
}
Since, this json file is flat, I am not able to get the children in the tree.
Any suggestion please?