API:EPrints/Apache/CRUD

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EPrints 3 Reference: Directory Structure - Metadata Fields - Repository Configuration - XML Config Files - XML Export Format - EPrints data structure - Core API - Data Objects


API: Core API

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NAME

EPrints::Apache::CRUD - Create, read, update and delete via HTTP

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SYNOPSIS

 $crud = EPrints::Apache::CRUD->new(
     repository => $repo,
     request => $r,
     datasetid => "eprint",
     dataobjid => "23",
   );
 

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DESCRIPTION

The CRUD (Create/Read/Update/Delete) module provides the Web API for manipulating content on the server. The API is an AtomPub implementation that exposes Import and Export plugins via simple URLs and HTTP content type negotiation.

You should use the <link> entries in the repository's home page to locate the CRUD endpoint, as they may change in the future:

 <link rel="Sword" href="https://myrepo/sword-app/servicedocument" />
 <link rel="SwordDeposit" href="https://myrepo/id/contents" />
 

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Examples

Create a new eprint based on a single file:

 curl -X POST \
   -i \
   -u user:password \
   -d 'Hello, World!' \
   -H 'Content-Type: text/plain' \
   https://myrepo/id/contents
 
 HTTP/1.1 201 Created
 Content-Type: application/atom+xml;charset=utf-8
 ...
 

Add a file to an existing eprint:

 curl -X POST \
   -i \
   -u user:password \
   -d 'Hello, World!' \
   -H 'Content-Disposition: attachment; filename=hello.txt' \
   -H 'Content-Type: text/plain' \
   https://myrepo/id/eprint/23/contents
 
 HTTP/1.1 201 Created
 Content-Type: application/atom+xml;charset=utf-8
 ...
 

Get an eprint's metadata in Atom XML:

 curl -X GET \
   -i \
   -u user:password \
   -H 'Accept: application/atom+xml' \
   https://myrepo/id/eprint/23
 
 HTTP/1.1 200 OK
 Content-Type: application/atom+xml;charset=utf-8
 ...
 

Get the list of contents (documents) of an eprint in Atom XML:

 curl -X GET \
   -i \
   -u user:password \
   -H 'Accept: application/atom+xml' \
   https://myrepo/id/eprint/23/contents
 
 HTTP/1.1 200 OK
 Content-Type: application/atom+xml;charset=utf-8
 ...
 

You can find more examples in the tests/84_sword.t unit test.

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URI layout

These URIs are relative to your EPrints HTTP/HTTPs root.

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/id/contents GET,HEAD,OPTIONS,POST

Requires authentication.

GET a list of the eprints owned by the user. POST to create a new EPrint object.

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/id/[datasetid]/[dataobjid] DELETE,GET,HEAD,OPTIONS,PUT

Requires authentication depending on user's privileges and object visibility.

GET an object's metadata or, for File objects, the file content. PUT to replace the metadata and/or contents (see Updating complex objects using PUT). If the object does not exist will attempt to create it with the given dataobjid (requires 'upsert' privilege).

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/id/[datasetid]/[dataobjid]/contents DELETE,GET,HEAD,OPTIONS,POST,PUT

Requires authentication depending on user's privileges and object visibility.

GET the logical contents of the object: documents for eprints or files for documents. PUT to replace the existing contents or POST to add to the existing contents.

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HTTP Content Negotiation

GET/HEAD requests are processed using Export plugins. POST/PUT requests are processed using Import plugins.

The plugin used depends on the request's Accept (GET/HEAD) or Content-Type (POST/PUT) header and the type of object being acted on. For example, the following request:

 GET /id/eprint/23 HTTP/1.1
 Accept: application/vnd.eprints.data+xml
 

Will search for an Export plugin that accepts objects of type dataobj/eprint and can produce output in the MIME type application/vnd.eprints.data+xml. This will most likely be the EP3 XML plugin.

In addition to the general plugin negotiation behaviour some special cases are supported to improve compatibility with Atom Pub/Web Browser clients:

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/id/eprint/...

Requesting EPrint objects as text/html will result in a 303 Redirect to the eprint object's abstract page or, if the eprint is not public, its View page.

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/id/document/.../contents

Requesting the /contents of a Document object will return the content of the document's main file.

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/id/file/...

Requesting a File object with no Accept header (or */*) will return the file's content.

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POST /id/.../contents

When creating new records via POST, content negotiation is performed against the Import plugins.

If no Import plugin supports the Content-Type header the content will be treated as application/octet-stream and stored in a new object. The resulting Atom entry will describe the new object (e.g. the eprint object in which the new document and file objects were created).

Otherwise, the result will depend on the Import plugin's output. Import plugins may produce a single object, multiple objects or an object plus content file(s).

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Content-Type header

If no Content-Type header is given the MIME type defaults to application/octet-stream for POSTs and PUTs.

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Content-Disposition header

If the Content-Disposition header is missing or does not contain a filename parameter the filename defaults to main.bin for POSTs and PUTs.

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Updating complex objects using PUT

Eprint objects contain zero or more documents, which each contain zero or more files. When you update (PUT) an eprint object the contained documents will only be replaced if the Import plugin defines new documents e.g. the Atom Import plugin will never define new documents so PUTing Atom content will only update the eprint's metadata. PUTing EP3 XML will replace the documents if you include a <documents> XML element.

PUTing to /contents will always replace all contents - PUTing to /eprint/23/contents is equivalent to DELETE /eprint/23/contents then POST /eprint/23/contents.

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PUT/DELETE from Javascript

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Upserting objects with PUT

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METHODS

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repository

$repo = $crud->repository()

Returns the current repository.

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request

$r = $crud->request()

Returns the current Apache2::RequestUtil.

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method

$method = $crud->method()

Returns the HTTP method.

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scope

$scope = $crud->scope()

Returns the scope of the action being performed.

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dataset

$dataset = $crud->dataset()

Returns the current dataset (if any).

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dataobj

$dataobj = $crud->dataobj()

Returns the current dataobj (if any).

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field

$field = $crud->field()

Returns the current field (if available);

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headers

$headers = $crud->headers()

Get the processed headers.

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options

@verbs = $crud->options()

Returns the available HTTP verbs for the current request.

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plugin

$plugin = $crud->plugin()

Returns the current plugin (if available).

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is_write

$bool = $crud->is_write()

Returns true if the request is not a read-only method.

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accept_type

$accept_type = $crud->accept_type()

Returns the EPrints type for the current request.

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check_packaging

$rc = $crud->check_packaging()

Check the Packaging header is ok, if given.

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resolve_relations

$dataobj = $crud->resolve_relations( $dataobj [, @relations ] )

Resolve the relation path from $dataobj and return the resulting dataobj.

Returns undef if there is no such related object.

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authen

$rc = $crud->authen

Returns HTTP code based of whether CRUD request can be authenticated.

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authz

$rc = $crud->authz

Returns HTTP code based of whether CRUD request can be authorized.

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parse_input

$list = $crud->parse_input( $plugin, $f [, %params ] )

Parse the content submitted by the user using the given $plugin. $f is called by epdata_to_dataobj to convert epdata to a dataobj.  %params are passed to the plugin's input_fh method.

Returns undef on error.

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create_dataobj

$dataobj = $crud->create_dataobj( $owner, $epdata )

Creates data object as user $owner with metadata from $epdata

Returns an EPrints::DataObj

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import_plugins

@plugins = $crud->import_plugins( [ %params ] )

Returns all matching import plugins against %params ordered by descending 'q' score.

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export_plugins

@plugins = $crud->export_plugins( [ %params ] )

Returns all matching export plugins against %params ordered by descending 'q' score.

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content_negotiate_best_plugin

$plugin = $crud->content_negotiate_best_plugin()

Work out the best plugin to export/update an object based on the client-headers.

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crud

EPrints::Apache::CRUD( $media_range )

Takes the $media_range string and returns array of acceptable MIME types. See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1 for more detail.

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handler

$rc = $crud->handler

Handler of CRUD requests.

Returns HTTP response code.

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delete

$rc = $crud->DELETE()

Handle DELETE requests.

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http_method_not_allowed

HTTP_METHOD_NOT_ALLOWED

Can't perform DELETE on /id/contents.

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http_not_found

HTTP_NOT_FOUND

No such object.

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http_conflict

HTTP_CONFLICT

Lock conflict with another user.

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http_no_content

HTTP_NO_CONTENT

Successfully removed the object.

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get

$rc = $crud->GET( [ $owner ] )

Handle GET requests.

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http_no_content

HTTP_NO_CONTENT

No sub-objects in /id/.../contents.

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http_not_acceptable

HTTP_NOT_ACCEPTABLE

More than one sub-object in /id/.../contents.

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http_unsupported_media_type

HTTP_UNSUPPORTED_MEDIA_TYPE

No Export plugin matches the Accept header/object type.

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http_see_other

HTTP_SEE_OTHER

Redirect to a non-CRUD EPrints page.

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http_not_found

HTTP_NOT_FOUND

Object not found.

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http_ok

HTTP_OK

Object outputted successfully.

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post

$rc = $crud->POST( [ $owner ] )

Handle POST requests.

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http_method_not_allowed

HTTP_METHOD_NOT_ALLOWED

Can only POST to /id/.../contents.

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http_bad_request

HTTP_BAD_REQUEST

No plugin for the SWORD Packaging header.

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http_created

HTTP_CREATED

Object(s) successfully created.

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put

$rc = $crud->PUT( [ $owner ] )

Handle PUT requests.

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http_unsupported_media_type

HTTP_UNSUPPORTED_MEDIA_TYPE

No Import plugin matched the Content-Type header/object type.

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http_range_not_satisfiable

HTTP_RANGE_NOT_SATISFIABLE

Range header is invalid or unsupported for the object type.

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http_forbidden

HTTP_FORBIDDEN

User does not have permission to create/update the object.

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http_created

HTTP_CREATED

Object was successfully created.

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http_no_content

HTTP_NO_CONTENT

Object was successfully updated.

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put_contents

$rc = $crud->PUT_contents( [ $owner ] )

Equivalent to DELETE /id/.../contents then POST /id/.../contents.

See DELETE and POST.

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metadata_relevant

$crud->metadata_relevant( $file )

Test and if suitable use $file as metadata source to updatie the associated EPrints::DataObj::EPrint.

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servicedocument

$crud->servicedocument

Gennerate response containing CRUD service document.

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on_behalf_of

$rc = $crud->on_behalf_of( $user )

Submit CRUD request on behalf od another user.

Returns HTTPS response code based on wehther request on behalf of is permitted.

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is_true

$boolean = EPrints::Apache::Crud::is_true( $header )

Tests if $header attribute is true.

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is_false

$boolean = EPrints::Apache::Crud::is_false( $header )

Tests if $header attribute is false.

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is_file_ok

$boolean = $crud->is_file_ok( $epdata )

Tests if files with $epdata were uploaded with corruption.

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process_headers

$boolean = $crud->process_headers

Process headers of CRUD request

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$boolean

$boolean = $crud->( %opts )

Generate SWORD error documents based on provided %opts.

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plugin_error

$boolean = $crud->plugin_error( $plugin, $messages )

Generate error message for import $plugin used with $messages provided.

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generate_error_document

$error_document = EPrints::Apache::Crud::generate_error_document( $repo, %opts )

Return error document for EPrints::Repository $repo using options from %opts.

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send_response

$rc = $crud->send_response( $status, $content_type, $content )

Output response to CRUD request with HTTP status code $status, content type $content_type.

Returns HTTP response code OK.

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SEE ALSO

http://en.wikipedia.org/wiki/Create,_read,_update_and_delete

http://en.wikipedia.org/wiki/Content_negotiation

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COPYRIGHT

© Copyright 2022 University of Southampton.

EPrints 3.4 is supplied by EPrints Services.

http://www.eprints.org/eprints-3.4/

LICENSE

This file is part of EPrints 3.4 http://www.eprints.org/.

EPrints 3.4 and this file are released under the terms of the GNU Lesser General Public License version 3 as published by the Free Software Foundation unless otherwise stated.

EPrints 3.4 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with EPrints 3.4. If not, see http://www.gnu.org/licenses/.

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