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https://issues.apache.org/jira/browse/COUCHDB-1303?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13842387#comment-13842387
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Ari Najarian commented on COUCHDB-1303:
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So... it's been 2 years since the last comment on this thread, but I thought
I'd throw my 2 cents in. I know this is much more complex an undertaking than I
can imagine, but I would find this functionality extremely useful were it
implemented. As far as the REST API is concerned, this is what I envision:
since bulk methods already take an array of documents (that currently have to
be specified), why not 'pipe' in the results of a view (with the same standard
query parameters to select different portions), and just include an additional
parameter to specify the design document / update handler to use on the
operation?
Say you want to 'reassign' a bunch of documents from one parent doc to another
(e.g. tasks on a project, new manager for a bunch of staff, etc.). The bulk
update API call could look something like this:
{noformat}/db/bulk_update?mode=view&source=ddoc/_view/tasks&handler=ddoc/_update/reassign_project&startkey=['task_id']&endkey=['task_id',{}]&new_project_id=1234{noformat}
or
{noformat}/db/bulk_update?mode=view&source=ddoc/_view/staff&handler=ddoc/_update/reassign_manager&startkey=['old_manager_id']&endkey=['old_manager_id',{}]&new_manager_id=1234{noformat}
The {{mode}} param could be 'view' or 'docs' - in the case of the former, you
provide the view name via {{source}}. In the case of the latter, you provide
the documents as JSON in the request body. Standard view query parameters
({{startkey, endkey, keys}}, etc.) could be used with {{mode=view}}, and any
additional params in the request would simply get passed into the update
handler, where they could be retrieved in {{req.form}} or {{req.query}}.
While not the prettiest implementation (and could definitely use some
refinement), all the pieces are there to source a document array from an
existing view, and a handler from an existing design document.
The real beauty of bulk update handlers implemented this way can be illustrated
in the following scenario: say that you're using email addresses as unique IDs
for all staff in your system. Some staff are managers, others are employees.
Employees have a 'manager' key whose value is the email address of the manager,
so you can group them all by manager by using a complex key on a view index.
One manager changes their email address IRL. So we PUT to:
{{db/_design/ddoc/_update/change_email/[email protected]}}
The change_email update handler looks like this (!!):
{code:javascript}
function(doc,req){
var old = doc.email;
doc.email = req.query.new;
if(doc.manager){
response = {
code: 302,
headers: {
"Location" : "/" + req.info.db_name +
"/bulk_update?mode=view&source=ddoc/_view/staff&handler=ddoc/_update/reassign_manager&startkey=['"
+ old + "']&endkey=['" + old + "',{}]&new_manager_id=" + doc.email,
"Content-Type" : "application/json"
},
body: ""
}
return[doc,response];
}
else{
return[doc,"Email has been updated"];
}
}
{code}
So, we update one record using a single update handler, and then conditionally
redirect to the _bulk_update handler to update all the "related" documents in
the database! Any time a manager changes their email address, we no longer have
to worry about updating all the other docs using middleware. This would be so
awesome.
I've come to rely very heavily on CouchApps, and the more I can do without
leaving the stack, the happier / more productive / more effective I am. Bulk
update handlers would fill a huge gap in my projects, by getting the server to
do more heavy lifting, instead of relying on the client to do everything.
I hope the possibilities I outlined above excite you guys as much as they
excite me. Perhaps we can revisit bulk update handlers in an upcoming version?
> Add a _bulk_update handler similar to _update but for bulk document changes
> ---------------------------------------------------------------------------
>
> Key: COUCHDB-1303
> URL: https://issues.apache.org/jira/browse/COUCHDB-1303
> Project: CouchDB
> Issue Type: New Feature
> Reporter: Benjamin Young
> Labels: api, update_request_handler
>
> _update handlers are great (and getting better!) for building RESTful API's
> inside CouchDB. One limitation I found tonight is that _update can only do a
> single document at a time. If the API I'm building needs to update multiple
> docs (in a similar fashion to _bulk_docs), then an outside "proxy" script is
> required. It would be ideal to have a _bulk_update handler to allow for the
> same functionality as _update, but with the ability to insert multiple
> documents at once.
> Perhaps the current _update handler API could be extended to support multiple
> IDs/documents, but a separate API endpoint would be seem reasonable if needed.
> Thanks for considering this idea.
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