Forums » Element Set example?

RSS feed for this topic

Info

Posted in Plugins
Started 1 year ago by mcyzyk
11 posts by 4 users
Latest reply from drhiii

Tags

mcyzyk Posted 1 year ago

Dear (er) Omekans,

Is there a full Element Set plugin example somwhere I could take a look at? I am trying to write a plugin that will integrate the ISO19115 Geographic Information metadata standard (element set) into Omeka. I've got its core elements in an $elements array, as illustrated on the Creating an Element Set page (http://omeka.org/codex/Creating_an_Element_Set), but having a full element set plugin (with directory structure, etc.) sure would help!

Best regards,

Mark Cyzyk
Johns Hopkins University
mcyzyk Posted 1 year ago

OK, it occurred to me earlier this morning that there already is a fine example of this: The Dublin Core Extended plugin. So looking at that now.

However, the code in the elements.php file is pretty different than what's posted to the official example: http://omeka.org/codex/Creating_an_Element_Set

The official example illustrates a simple array of elements, while this elements.php file uses an array of arrays. Not sure what to do. Also, the Dublin Core Extended plugin seems to model a hierarchy of elements via a "_refines" attribute. This is not mentioned in the official example, rather, we are told to build hierarchies by concatenating elements with a colon. Looking into this further...

Mark
John Flatness (Omeka Dev Team) Posted 1 year ago
Hi Mark,

In fact, the official example you linked to also uses an array of arrays, although it's possible to miss that because of the way the example is presented. The way it works is like this:

Each "inner array" represents one Element. So
```
array(
    'name'           => 'Element Name',
    'description'    => 'Element Description',
)
```
describes a single Element. Since you're adding an ElementSet, what you pass to insert_element_set is an array of those inner arrays.

mcyzyk Posted 1 year ago

Thanks, John!

So here is the content of my elements.php file:

<?php
$elements = array(
    array(
        'name'           => [(string) ISO19115 Core, required],
        'description'    => [(string) Core elements from the North American Profile of the ISO19115 metadata standard: Geographic information, optional],
		'MD_Metadata:MD_DataIdentification.citation:CI_Citation.title' => [(string) Dataset title, optional],
		'MD_Metadata.contact:CI_ResponsibleParty' => [(string) Metadata point of contact, optional],
		'MD_Metadata::MD_DataIdentification.citation:CI_Citation.date' => [(string) , optional],
		'MD_Metadata.dateStamp' => [(string) Dataset reference date, optional],
		'MD_Metadata:MD_DataIdentification.abstract' => [(string) Abstract describing the dataset, optional],
		'MD_Metadata:MD_DataIdentification.topicCategory' => [(string) Dataset topic category, optional],
		'MD_Metadata:MD_DataIdentification.language' => [(string) Dataset language, optional],
		'MD_Metadata:MD_DataIdentification.extent:EX_Extent:EX_GeographicExtent:EX_GeographicBoundingBox' => [(string) Geographic location of the dataset (by four coordinates), optional],
		'MD_Metadata:MD_DataIdentification.extent:EX_Extent:EX_GeographicExtent:EX_GeographicDescription' => [(string) Geographic location of the dataset (by geographic identifier), optional],
		'MD_Metadata.language' => [(string) Metadata language, optional],
		'MD_Metadata:MD_DataIdentification.characterSet' => [(string) Dataset character set, optional],
		'MD_Metadata.characterSet' => [(string) Metadata character set, optional],
		'MD_Metadata:MD_DataIdentification.extent:EX_Extent:EX_TemporalExtent' => [(string) Additional extent information for the dataset (temporal), optional],
		'MD_Metadata:MD_DataIdentification.extent:EX_Extent:EX_VerticalExtent' => [(string) Additional extent information for the dataset (vertical), optional],
		'MD_Metadata:MD_DataIdentification.pointOfContact:CI_ResponsibleParty' => [(string) Dataset responsible party, optional],
		'MD_Metadata:DQ_DataQuality.lineage:LI_Lineage' => [(string) Lineage, optional],
		'MD_Metadata:MD_Distribution:MD_DigitalTransferOption.onLine:CI_OnlineResource' => [(string) On-line resource, optional],
		'MD_Metadata:MD_DataIdentification.spatialRepresentationType' => [(string) Spatial representation type, optional],
		'MD_Metadata.fileIdentifier' => [(string) Metadata file identifier, optional],
		'MD_Metadata:MD_Distribution:MD_Format.name' => [(string) Distribution format name, optional],
		'MD_Metadata:MD_Distribution:MD_Format.version' => [(string) Distribution format version, optional],
		'MD_Metadata.metadataStandardName' => [(string) Metadata standard name, optional],
		'MD_Metadata.metadataStandardVersion' => [(string) Metadata standard version, optional],
		'MD_Metadata:MD_ReferenceSystem' => [(string) Reference system, optional],
		'MD_Metadata:MD_DataIdentification.spatialResolution:MD_Resolution.equivalentScale' => [(string) Spatial resolution of the dataset (equivalent scale), optional],
		'MD_Metadata:MD_DataIdentification.spatialResolution:MD_Resolution.distance' => [(string) Spatial resolution of the dataset (distance), optional]
    ),
);

Does this look correct?

After making a copy, I've gone through the codebase for the Dublin Core Extended plugin and have edited class names, variable names, etc, translating from, e.g., 'DublinCoreExtended' to 'ISO19115Core' where needed, I've installed this new directory tree/codebase in my plugins directory, and have installed it from within the Omeka interface. And yet, it does not show as a registered Element Set. All I got was a blank screen when installing it, so I guess something is wrong. Looking for a log now...

Mark

John Flatness (Omeka Dev Team) Posted 1 year ago

This is another case of the format of the documentation getting in the way a little.

What you want should look a little more like this:

<?php
$elementSetMetadata = array(
    'name' => 'ISO19115 Core',
    'description' => 'Core elements from the North American Profile of the ISO19115 metadata standard.');

$elements = array(
    array(
        'name' => 'Name of your metadata element goes here',
        'description' => 'Description of your element goes here'
    ),
    array(
        'name' => 'Name of the 2nd metadata element',
        'description' => 'Description of the 2nd element'
    )
    // There should be an array inside the bigger array for each
    // Element you're trying to add.
);

//Then, you would call this function to actually add the element set
insert_element_set($elementSetMetadata, $elements);

The portions of the documentation containing text in brackets are simply for the benefit of the reader; they tell you which array elements must be included and which are optional.

I hope this makes the situation somewhat more clear.

John Flatness (Omeka Dev Team) Posted 1 year ago

Sigh.

Apologies, the code block above got a little mangled when I input it. What you want is:

<?php
$elementSetMetadata = array(
    'name' => 'ISO19115 Core',
    'description' => 'Core elements from the North American Profile of the ISO19115 metadata standard.');

$elements = array(
    array(
        'name' => 'Name of your metadata element goes here',
        'description' => 'Description of your element goes here',
    ),
    array(
        'name' => 'Name of the 2nd metadata element',
        'description' => 'Description of the 2nd element',
    )
    // There should be an array inside the bigger array for each
    // Element you're trying to add.
);

//Then, you would call this function to actually add the element set
insert_element_set($elementSetMetadata, $elements);

mcyzyk Posted 1 year ago

Thanks again, John! Much clearer now.

So this would then be in my plugin.php file?:

insert_element_set($elementSetMetadata, $elements);

Mark
John Flatness (Omeka Dev Team) Posted 1 year ago

Right. The variable names of the arrays you create in element.php should be the same names in the call to insert_element_set in your plugin.php.

So, if you've kept the same names as my example above, then your line is perfect.
drhiii Posted 1 year ago

I am attempting to add some Element Set fields, actually just one, to the DC and Extended DC plugin. Trying to get my head around how to accomplish this.

Have reviewed the Creating an Element Set How To and the concepts make sense. Now for the duh questions.

One creates a plugin. In the How To, does that mean I just need to create a single file that will suffice as a plugin?

Or, do I need to copy the DC Extended Plugin file structure and edit elements.php and plugins.php, so that I end up with the same framework as the DC Extended Plugin?

Am not quite getting my head around this yet.

All I am trying to accomplish for the moment is a demo that adds a single 'Location' field after Identifier. My next thought, which I will attempt in a few hours, is to just add to the DC Extended code and insert these lines. However, having not done this yet, and will build a temp Omeka to practice on... if I add some Element Sets to the existing DC Extended plugin, I have not yet discovered if this will work. Would I need to Deactivate and Reactivate the Plugin and would the additional Elements be added?

Or, do I need to Uninstall and Reinstall the DC Extended Plugin, and would that 'read in' the additional Elements?

My concern with Uninstalling and Reinstalling is I believe I read that doing this would remove all data that has been added to these extended fields. This true?

Hopefully someone can shed some light on how to create a Element Set plugin from my questions above... whether it is a single file, or is it using the same DC Extended set of files that I just vanquish and add only the additional fields, or... something else. Don't quite have my head around it yet.

Help?

I will of course pass along my education to the next folks who struggle, and will continue the knowledge transfer.

tx
jsafley (Omeka Dev Team) Posted 1 year ago

> One creates a plugin. In the How To, does that mean I just need to create
> a single file that will suffice as a plugin? Or, do I need to copy the DC
> Extended Plugin file structure and edit elements.php and plugins.php, so
> that I end up with the same framework as the DC Extended Plugin?

We recommend using existing plugins as templates for new ones. They often have similar structures and commonly used hooks/filters needed to build something functional. But, at the very least, you need a plugin directory containing a file named plugin.php.

> All I am trying to accomplish for the moment is a demo that adds a single
> 'Location' field after Identifier.

Instead of adding a "Location" element, you could use the "Spatial Coverage" or "Bibliographic Citation" elements (depending on your meaning of "Location") that come with the Dublin Core Extended plugin.

> if I add some Element Sets to the existing DC Extended plugin, I have not
> yet discovered if this will work. Would I need to Deactivate and Reactivate
> the Plugin and would the additional Elements be added? Or, do I need to
> Uninstall and Reinstall the DC Extended Plugin, and would that 'read in'
> the additional Elements?

I'm not sure I know what you're trying to accomplish. Element sets are predefined collections of elements (fields). To be clear, are you looking to add a new element set via the DC Extended plugin? If so it would be wiser to create a new plugin with the sole purpose of adding the element set. Just use the insert_element_set() function in the plugin's "install" hook. (The DC Extended plugin does not create an element set in this manner; rather, it adds additional elements directly to the existing Dublin Core element set.)

Or are you looking to add an element to the DC element set via the DC Extended plugin? Conceivably, you could try this by describing your "Location" element in the $elements array in elements.php; though I don't recommend it. Modifying released and stable plugins may result in unexpected behavior. Moreover, there are no guarantees that future releases of the plugin will work with your modified (forked) version. Instead, you can create a new plugin with the sole purpose of adding the element. In the "install" hook, just instantiate a new Element record, assign it the necessary properties, and save it. There's an example of this in DublinCoreExtendedPlugin::_addElements().

Jim
drhiii Posted 1 year ago

Thank you for your response. I will absorb this information and see if I can add to the existing nomenclature.

While it is not important for the immediate term, I will need to revise, which means I will need to "add" fields to the existing DC structure. I am working with a museum that has utilized a homebrewed set of naming conventions, and I will have to integrate their naming conventions with the DC Core.

I know I know... why not just have them ameliorate into the existing standards? Easier said than done. There are some fixed in their ways people who are grudgingly going along with this, and I getting this far with marrying up existing standards with their few homegrown fields has been work.

I have not digested your response yet but if I can take liberty and ask, tho I hopefully will discover the answer in reading your response...

There is an internal DC Core, and DC Extended Plugin... your instructions indicated that I can create and additional Plugin that 'appends' to these two Element Sets, yes? A completely different plugin that gets 'called'.

One thing I ran into was, when I tried to Deactivate the DC Extended, the fields remained in all the Items. So I tried to Uninstall the DC Extended and it went to a blank screen. Refreshing went no where, but when I circled back around to see if the Plugin indeed Uninstalled, it did not. I could never get it to Uninstall. Just an FYI.

Anyway, thank you very much for your response. I will press forward and see if I can create a new plugin. Having just enough skills to be dangerous, I can see this is an area that others will also stumble on and trust Omeka folks are reviewing how this functionality can be approached by newbies, or slightly dangerous folks with minimal skillsets like me.

Omeka is terrific.

regards, david
drhiii Posted 1 year ago

Also, John, you are correct. I set up a second test Omeka install and fiddled with altering the DC Extended as well. It blew up in face. Is why we create alternate test domains yes?

Something occurred to me, which may be recommended against. But dawned on me that being able to alter, not the Element Set, but at least the human readable part of the sets. Since the DC Extended fields are reasonably granular, thought it might be better served to add text, like examples, to help the mom and pop crews that will be adding metadata to these fields.

One way of course is to hand them some training and a printed cheat sheet. Would be nice tho to be able to add some additional text to the existing text, and even say some external links to video tutorial examples.

It gets into altering the existing DC Extended plugin and I have already found this is NOT advisable. But, is there a way to not alter the existing array, but add to the human readable examples that parallel the array of fields?

Let me know when this gets annoying. I can't help but think others will follow and have similar questions...

Reply

You must log in to post.

Forums » Element Set example?

Info

Tags

Reply

About

Help

Downloads