Hi, Jem:
The REST API supports a server-side XQuery or XSLT transform to modify a
document on write or read
that sounds similar to what you are expecting. The transform has to be
installed first by a user with the
rest-administrator role. The transform can take whatever parameters you want
and can throw an error
if it's not appropriate to write the document. Please see:
http://docs.marklogic.com/guide/rest-dev/transforms
The specific flow of control you sketch below sounds similar to optimistic
locking:
http://docs.marklogic.com/guide/rest-dev/documents#id_56659
So, for that case, you might not need a server-side transform.
Hoping that's useful,
Erik Hennum
________________________________________
From: [email protected]
[[email protected]] On Behalf Of Jem Rayfield
[[email protected]]
Sent: Monday, November 19, 2012 8:51 AM
To: MarkLogic Developer Discussion; MarkLogic Developer Discussion
Subject: Re: [MarkLogic Dev General] Marklogic REST API. [Multi-statement tx]
Extending the REST API every time you want to do constraint controlled Document
Create, Update, Deletes seems like a fair amount of extra work.
If this is the approach then I guess I can look at it.
I was just thinking that perhaps something along the lines of would be
availible:
/documents&query=XQuery&bind:x=X&bind:y=Y
Update /documents using the adhoc XQuery with a set of variable bindings. Where
these bindings could be the XML for the doc and params.
I guess I need to look at extensions.
Thanks for the pointer re fn:exists().
-----Original Message-----
From: [email protected] on behalf of Michael Blakeley
Sent: Mon 19/11/2012 4:41 PM
To: MarkLogic Developer Discussion
Subject: Re: [MarkLogic Dev General] Marklogic REST API. [Multi-statement tx]
Jem, why not extend the REST API to implement that as a single request? That
should give you the benefits of using the REST API, without requiring multiple
requests.
http://docs.marklogic.com/guide/rest-dev/extensions discusses this feature and
has an example that you could modify to suit your application.
BTW in your sample code below I would probably use fn:exists() rather than
xdmp:exists(). You are using that boolean to decide whether or not to update
the database. Therefore you probably want ACID consistency guarantees, which
xdmp:exists explicitly avoids in its subexpression because it always runs
timestamped. Replacing it with fn:exists(doc($documentUri)) will read-lock any
document at $documentUri, which guarantees consistency and avoids a potential
race condition.
-- Mike
On 19 Nov 2012, at 07:59 , Jem Rayfield <[email protected]> wrote:
> Hi,
>
> Would I be correct that the following type of XQuery should be translated to
> a sequence of REST calls using a tx-id.
> So, a single simple XQuery update such as:
>
> if (xdmp:exists(doc($documentUri)))
> then (
> if ($timeCode < xs:dateTime(doc($documentUri)/document/header/timeStamp) )
> then ()
> else (
> xdmp:document-insert($documentUri, xdmp:unquote($xml),
> xdmp:default-permissions(), local:getCollections())
> )
> )else (
> xdmp:document-insert($documentUri, xdmp:unquote($xml),
> xdmp:default-permissions(), local:getCollections())
> )
>
> Would be translated to a number of REST calls:
>
> Get a transaction; /transactions
> Invoke XQuery to get time stamp using the tx id; /query
> Update Document using the tx id; /documents
>
> Or is there a better way of doing this using the current REST API spec?
> There could be a lot of I/O etc for something quite simple.
>
> I may have missed something here so please do point me in the right direction.
>
> Cheers
> Jem
>
>
>
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