Examples of xPDO XML Schema Files

98 Posts

jimsheppard Reply #1, 13 years, 8 months ago

I've just spent the evening attempting to get my head around the Dashboard examples of xPDO Schema Files. I think I have got it now but in the process it occurred to me that the author and editor of this section could help other newbies simply by prefixing the foreign keys in the various tables with an 'FK' At the moment they all have the same name (ex blogpost_id) in both the primary and secondary table which is fine once you understand what is going on but but initially it is difficult when trying to understand what goes where.

Otherwise a great tutorial - Thanks

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Mark Hamstra Reply #2, 13 years, 8 months ago

I'm not exactly sure what you mean - what exactly is unclear, the way the keys or relations work? Can you maybe provide some snippets of the text/examples of how you would make it clearer?

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98 Posts

jimsheppard Reply #3, 13 years, 8 months ago

Quote from: markh at Jan 21, 2013, 10:50 PM

I'm not exactly sure what you mean - what exactly is unclear, the way the keys or relations work? Can you maybe provide some snippets of the text/examples of how you would make it clearer?

For me and I have since noticed others on this forum making the same comment it is the naming of the fields in the examples for instance

MySQL Table Definitions	
CREATE TABLE `blogposts` (
  `blogpost_id` int(11) NOT NULL AUTO_INCREMENT,
  `content` text,
  PRIMARY KEY (`blogpost_id`)
) ENGINE=MyISAM;
 
CREATE TABLE `comments` (
  `comment_id` int(11) NOT NULL AUTO_INCREMENT,
  `blogpost_id` int(11) DEFAULT NULL,
  `comment` text,
  PRIMARY KEY (`comment_id`)
) ENGINE=MyISAM;

Here the field `blogpost_id` appears in both the primary and secondary tables. For the newbie such as myself trying to make the leap into PDO it becomes confusing later on

<composite alias="Comments" class="Comments" local="blogpost_id" foreign="blogpost_id" cardinality="many" owner="local" />

to follow which `blogpost_id` goes where.

A simple addition in the secondary table like this

CREATE TABLE `comments` (
  `comment_id` int(11) NOT NULL AUTO_INCREMENT,
  `fk_blogpost_id` int(11) DEFAULT NULL,
  `comment` text,
  PRIMARY KEY (`comment_id`)
) ENGINE=MyISAM;

and (if I have it right)

<composite alias="Comments" class="Comments" local="fk_blogpost_id" foreign="blogpost_id" cardinality="many" owner="local" />

might make one's head spin a bit less slowly (:>)!

Give a man the answer, and he’ll only have a temporary solution. Teach him the principles that led you to that answer, and he will be able to create his own solutions in the future.

☆ A M B ☆
3,141 Posts

Mark Hamstra Reply #4, 13 years, 8 months ago

Ahh, okay, makes sense.

Personally I wouldn't make it fk_blogpost_id, but just blogpost, but that's just a personal preference; there's no rules on what you can or cannot name fields in xPDO (as long as it's fine with MySQL tongue

). I've updated the docs.

Mark Hamstra • Developer spending his days working on Premium Extras and a MODX Site Dashboard with the ability to remotely upgrade MODX and extras to make the MODX world a little better.

Tweet me @mark_hamstra, check my infrequent blog at markhamstra.com, my slightly more frequent ramblings at MODX.today or see code at Github.

98 Posts

jimsheppard Reply #5, 13 years, 8 months ago

Quote from: markh at Jan 22, 2013, 09:17 AM

Ahh, okay, makes sense.

Personally I wouldn't make it fk_blogpost_id, but just blogpost, but that's just a personal preference; there's no rules on what you can or cannot name fields in xPDO (as long as it's fine with MySQL ). I've updated the docs.

As you say it is personal preference, but in the case of the tutorial I believe it is less confusing if the fields in the tables do not have the same name.

Give a man the answer, and he’ll only have a temporary solution. Teach him the principles that led you to that answer, and he will be able to create his own solutions in the future.

98 Posts

jimsheppard Reply #6, 13 years, 8 months ago

Mark, I just had a look at the docs. Yes that is clearer now. For sake of consistency could you do the same with the Many to Many example too?

MySQL Table Definitions
	
CREATE TABLE `blogposts` (
  `blogpost_id` int(11) NOT NULL AUTO_INCREMENT,
  `content` text,
  PRIMARY KEY (`blogpost_id`)
) ENGINE=MyISAM;
 
CREATE TABLE `tags` (
  `tag_id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`tag_id`)
) ENGINE=MyISAM;
 
/* The Join Table: */
CREATE TABLE `blogposts_tags` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `blogpost_id` int(11) DEFAULT NULL,
  `tag_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM;

Give a man the answer, and he’ll only have a temporary solution. Teach him the principles that led you to that answer, and he will be able to create his own solutions in the future.

☆ A M B ☆
3,141 Posts

Mark Hamstra Reply #7, 13 years, 8 months ago

Done

Mark Hamstra • Developer spending his days working on Premium Extras and a MODX Site Dashboard with the ability to remotely upgrade MODX and extras to make the MODX world a little better.

Tweet me @mark_hamstra, check my infrequent blog at markhamstra.com, my slightly more frequent ramblings at MODX.today or see code at Github.

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BobRay Reply #8, 13 years, 8 months ago

I like it. I remember being thrown by the fact that the foreign key in the modUserProfile object is called 'internalKey' wink

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Mark Hamstra Reply #9, 13 years, 8 months ago

Quote from: BobRay at Jan 22, 2013, 04:17 PM

I like it. I remember being thrown by the fact that the foreign key in the modUserProfile object is called 'internalKey'

I still don't get why it's called that, lol. Seems kind of random, but then again: naming things is one of the hardest things in development wink

Mark Hamstra • Developer spending his days working on Premium Extras and a MODX Site Dashboard with the ability to remotely upgrade MODX and extras to make the MODX world a little better.

Tweet me @mark_hamstra, check my infrequent blog at markhamstra.com, my slightly more frequent ramblings at MODX.today or see code at Github.