Given the following code:
listView.ItemsSource =
App.azureClient.GetTable<SomeTable>().ToIncrementalLoadingCollection();
We get incremental loading without further changes.
But what if we modify the read.js server side script to e.g. use mssql to query another table instead. What happens to the incremental loading? I'm assuming it breaks; if so, what's needed to support it again?
And what if the query used the untyped version instead, e.g.
App.azureClient.GetTable("SomeTable").ReadAsync(...)
Could incremental loading be somehow supported in this case, or must it be done "by hand" somehow?
Bonus points for insights on how Azure Mobile Services implements incremental loading between the server and the client.
The incremental loading collection works by sending the $top and $skip query parameters (those are also sent when you do a query by using the .Take and .Skip methods in the table). So if you want to modify the read script to do something other than the default behavior, while still maintaining the ability to use that table with an incremental loading collection, you need to take those values into account.
To do that, you can ask for the query components, which will contain the values, as shown below:
function read(query, user, request) {
var queryComponents = query.getComponents();
console.log('query components: ', queryComponents); // useful to see all information
var top = queryComponents.take;
var skip = queryComponents.skip;
// do whatever you want with those values, then call request.respond(...)
}
The way it's implemented at the client is by using a class which implements the ISupportIncrementalLoading interface. You can see it (and the full source code for the client SDKs) in the GitHub repository, or more specifically the MobileServiceIncrementalLoadingCollection class (the method is added as an extension in the MobileServiceIncrementalLoadingCollectionExtensions class).
And the untyped table does not have that method - as you can see in the extension class, it's only added to the typed version of the table.
Related
I wrote a transformation in xquery which unquotes an XML-String and inserts a element with its content. This works fine.
I need to create a collection dependant on the root element of this element as well. I can't do this on new documents as xdmp:document-add-collections() is not working. How do I add the collection to new Documents in transformations?
Here my ServerSide xQuery Code:
xquery version "1.0-ml";
module namespace transform = "http://marklogic.com/rest-api/transform/smtextdocuments";
import module namespace mem = "http://xqdev.com/in-mem-update" at '/MarkLogic/appservices/utils/in-mem-update.xqy';
declare function transform(
$context as map:map,
$params as map:map,
$content as document-node()
) as document-node()
{
let $uri := base-uri($content)
let $doccont := $content/smtextdocuments/documentcontent
let $newcont := xdmp:unquote($doccont)
let $contname := node-name($newcont/*)
let $result := if ( exists($content/smtextdocuments/content))
then mem:node-replace($content/smtextdocuments/content, <content>11{$newcont}</content>)
else mem:node-insert-after($doccont, <content>{$newcont}</content>)
let $log := xdmp:log($content)
return (
$result,
xdmp:document-add-collections($uri, fn:string($contname)),
xdmp:document-remove-collections($uri, "raw")
)
};
The script ist running with the java api (4.0.4) create methode via parameter ServerTransform transform. As per documentation the transformation script is running before the document is stored in the Database.
Its a new document; I need to transform the content and then create the collection.
I can see the document after the create, the content is available. Just the collection is missing. I can try xdmp:document-insert method but is it correct writing the document while create is running?.
The transform mechanism of the Java API / REST API takes responsibility for the document write. At present, there's no way for the transform to supply collections to the writer. That would be a reasonable request for enhancement.
The transform shouldn't attempt to write the document, because the writer would also attempt to write the same document.
One alternative would be to transform the document in Java before writing it and specify the collection as part of the write request.
Another alternative would be to rewrite the transform as a resource service extension, implement the write within the resource service extension, and modify the Java client to send the document to the resource service extension.
Depending on the model, a final alternative might be to use a range index on an element within the document to collect documents into sets instead of using a collection on the document.
Hoping that helps,
What do you mean by "new documents"? Is the document already inserted into the MarkLogic database at the time you are adjusting the collections of it? If not, you may want to modify your return to ($result, xdmp:document-insert($uri, $result, xdmp:default-permissions(), fn:string($contname)) ) for that case.
Otherwise, can you edit your question to share the error or problem more specifically you are facing?
It is a pity that REST transforms do not allow this, like MLCP transforms do. Until changed you have the options drawn by ehennum, or you can consider delaying adding of collections to a pre- or post-commit trigger. It takes some overhead, but it sometimes makes perfect sense to do something like that in a trigger, since it makes sure it is always enforced, and a good place to do content validation, audit logging, and things like that as well.
HTH!
I'm using the ML9 Java API to upload a search options file to the DB with a name that I can use later in my search call. I would now like to write an xquery transform to highlight the query-matches in a set of elements in the response. Standard snippets won't work for me since they only bring back the fields in which there are matches and because they may not bring back the complete field value, but only the immediate context of the match.
So I want to use the cts:highlight function in a custom transform and want to pass to it the name of the options that I have uploaded into the DB. My question is how I can best get the options element from the DB using the name passed in to the transform method. I want to use this to construct the cts:query that I can pass in to the cts:highlight call as in:
let $query := cts:query(search:parse($query-string, $options))
let $result := cts:highlight($doc, $query, <markup>{$cts:text}
</markup>)
I was thinking I could pass in the query-string and the name of the pre-loaded options and use these to construct the cts:query, but don't know how to get the options from the name.
I found a way to avoid having to read the options. Setting the option 'return-query' to true adds a search:query node to the search:response which is passed to the transform method as the document-node. I'm then able to get this directly in the transform method to use in cts:highlight as:
let $query := cts:query($response/search:response/search:query/*[1])
The options are stored in the modules database associated with your REST instance. You could theoretically dig them out, though that would be relying on an implementation detail (the URI).
You might look into a combination of extract-document-data, as Sam mentioned, plus a search result transform, rather than the heavier approach of doing your own search through what I'd guess is a read transform.
Another alternative might be a custom snippeter that you pull into your options via transform-results. See http://docs.marklogic.com/guide/search-dev/query-options#id_58295.
I am building a REST API which connects to a NEO4J instance. I am using the koa-neo4j library as the basis (https://github.com/assister-ai/koa-neo4j-starter-kit). I am a beginner at all these technologies but thanks to some help from this forum I have the basic functionality working. For example the below code allows me to create a new node with the label "metric" and set the name and dateAdded propertis.
URL:
/metric?metricName=Test&dateAdded=2/21/2017
index.js
app.defineAPI({
method: 'POST',
route: '/api/v1/imm/metric',
cypherQueryFile: './src/api/v1/imm/metric/createMetric.cyp'
});
createMetric.cyp"
CREATE (n:metric {
name: $metricName,
dateAdded: $dateAdded
})
return ID(n) as id
However, I am struggling to know how I can approach more complicated examples. How can I handle situations when I don't know how many properties will be added when creating a new node beforehand or when I want to create multiple nodes in a single post statement. Ideally I would like to be able to pass something like JSON as part of the POST which would contain all of the nodes, labels and properties that I want to create. Is something like this possible? I tried using the below Cypher query and passing a JSON string in the POST body but it didn't work.
UNWIND $props AS properties
CREATE (n:metric)
SET n = properties
RETURN n
Would I be better off switching tothe Neo4j Rest API instead of the BOLT protocol and the KOA-NEO4J framework. From my research I thought it was better to use BOLT but I want to have a Rest API as the middle layer between my front and back end so I am willing to change over if this will be easier in the longer term.
Thanks for the help!
Your Cypher syntax is bad in a couple of ways.
UNWIND only accepts a collection as its argument, not a string.
SET n = properties is only legal if properties is a map, not a string.
This query should work for creating a single node (assuming that $props is a map containing all the properties you want to store with the newly created node):
CREATE (n:metric $props)
RETURN n
If you want to create multiple nodes, then this query (essentially the same as yours) should work (but only if $prop_collection is a collection of maps):
UNWIND $prop_collection AS props
CREATE (n:metric)
SET n = props
RETURN n
I too have faced difficulties when trying to pass complex types as arguments to neo4j, this has to do with type conversions between js and cypher over bolt and there is not much one could do except for filing an issue in the official neo4j JavaScript driver repo. koa-neo4j uses the official driver under the hood.
One way to go about such scenarios in koa-neo4j is using JavaScript to manipulate the arguments before sending to Cypher:
https://github.com/assister-ai/koa-neo4j#preprocess-lifecycle
Also possible to further manipulate the results of a Cypher query using postProcess lifecycle hook:
https://github.com/assister-ai/koa-neo4j#postprocess-lifecycle
Following these guides https://developers.google.com/apps-script/guides/rest/quickstart/target-script and https://developers.google.com/apps-script/guides/rest/quickstart/nodejs, I am trying to use the Execution API in node to return some data that are in a Google Spreadsheet.
I have set the script ID to be the Project Key of the Apps Script file. I have also verified that running the function in the Script Editor works successfully.
However, when running the script locally with node, I get this error:
The API returned an error: Error: ScriptError
I have also made sure the script is associated with the project that I use to auth with Google APIs as well.
Does anyone have any suggestion on what I can do to debug/ fix this issue? The error is so generic that I am not sure where to look.
UPDATE: I've included a copy of the code in this JSBin (the year function is the entry point)
https://jsbin.com/zanefitasi/edit?js
UPDATE 2: The error seems to be caused by the inclusion of this line
var spreadsheet = SpreadsheetApp.open(DriveApp.getFileById(docID));
It seems that I didn't request the right scopes. The nodejs example include 'https://www.googleapis.com/auth/drive', but I also needed to include 'https://www.googleapis.com/auth/spreadsheets' in the SCOPES array. It seems like the error message ScriptError is not very informative here.
In order to find what scopes you'd need, to go the Script Editor > File > Project Properties > Scopes. Remember to delete the old credentials ~/.credentials/old-credential.json so that the script will request a new one.
EDIT: With the update in information I took a closer look and saw you are returning a non-basic type. Specifically you are returning a Sheet Object.
The basic types in Apps Script are similar to the basic types in
JavaScript: strings, arrays, objects, numbers and booleans. The
Execution API can only take and return values corresponding to these
basic types -- more complex Apps Script objects (like a Document or
Sheet) cannot be passed by the API.
https://developers.google.com/apps-script/guides/rest/api
In your Account "Class"
this.report = spreadsheet.getSheetByName(data.reportSheet);
old answer:
'data.business_exp' will be null in this context. You need to load the data from somewhere. Every time a script is called a new instance of the script is created. At the end of execution chain it will be destroyed. Any data stored as global objects will be lost. You need to save that data to a permanent location such as the script/user properties, and reloaded on each script execution.
https://developers.google.com/apps-script/reference/properties/
I'm writing a REST api in node js that will execute a sql query and send the results;
in the request I need to send the WHERE conditions; ex:
GET 127.0.0.1:5007/users //gets the list of users
GET 127.0.0.1:5007/users
id = 1 //gets the user with id 1
Right now the conditions are passed from the client to the rest api in the request's headers.
In the API I'm using sequelize, an ORM that needs to receive WHERE conditions in a particular form (an object); ex: having the condition:
(x=1 AND (y=2 OR z=3)) OR (x=3 AND y=1)
this needs to be formatted as a nested object:
-- x=1
-- AND -| -- y=2
| -- OR ----|
| -- z=3
-- OR -|
|
| -- x=3
-- AND -|
-- y=1
so the object would be:
Sequelize.or (
Sequelize.and (
{x=1},
Sequelize.or(
{y=2},
{z=3}
)
),
Sequelize.and (
{x=3},
{y=1}
)
)
Now I'm trying to pass a simple string (like "(x=1 AND (y=2 OR z=3)) OR (x=3 AND y=1)"), but then I will need a function on the server that can convert the string in the needed object (this method in my opinion has the advantage that the developer writing the client, can pass the where conditions in a simple way, like using sql, and this method is also indipendent from the used ORM, with no need to change the client if we need to change the server or use a different ORM);
The function to read and convert the conditions' string into an object is giving me headache (I'm trying to write one without success, so if you have some examples about how to do something like this...)
What I would like to get is a route capable of executing almost any kind of sql query and give the results:
now I have a different route for everything:
127.0.0.1:5007/users //to get all users
127.0.0.1:5007/users/1 //to get a single user
127.0.0.1:5007/lastusers //to get user registered in the last month
and so on for the other tables i need to query (one route for every kind of request I need in the client);
instead I would like to have only one route, something like:
127.0.0.1:5007/request
(when calling this route I will pass the table name and the conditions' string)
Do you think this solution would be a good solution or you generally use other ways to handle this kind of things?
Do you have any idea on how to write a function to convert the conditions' string into the desired object?
Any suggestion would be appreciated ;)
I would strongly advise you not to expose any part of your database model to your clients. Doing so means you can't change anything you expose without the risk of breaking the clients. One suggestion as far as what you've supplied is that you can and should use query parameters to cut down on the number of endpoints you've got.
GET /users //to get all users
GET /users?registeredInPastDays=30 //to get user registered in the last month
GET /users/1 //to get a single user
Obviously "registeredInPastDays" should be renamed to something less clumsy .. it's just an example.
As far as the conditions string, there ought to be plenty of parsers available online. The grammar looks very straightforward.
IMHO the main disadvantage of your solution is that you are creating just another API for quering data. Why create sthm from scratch if it is already created? You should use existing mature query API and focus on your business logic rather then inventing sthm new.
For example, you can take query syntax from Odata. Many people have been developing that standard for a long time. They have already considered different use cases and obstacles for query API.
Resources are located with a URI. You can use or mix three ways to address them:
Hierarchically with a sequence of path segments:
/users/john/posts/4711
Non hierarchically with query parameters:
/users/john/posts?minVotes=10&minViews=1000&tags=java
With matrix parameters which affect only one path segment:
/users;country=ukraine/posts
This is normally sufficient enough but it has limitations like the maximum length. In your case a problem is that you can't easily describe and and or conjunctions with query parameters. But you can use a custom or standard query syntax. For instance if you want to find all cars or vehicles from Ford except the Capri with a price between $10000 and $20000 Google uses the search parameter
q=cars+OR+vehicles+%22ford%22+-capri+%2410000..%2420000
(the %22 is a escaped ", the %24 a escaped $).
If this does not work for your case and you want to pass data outside of the URI the format is just a matter of your taste. Adding a custom header like X-Filter may be a valid approach. I would tend to use a POST. Although you just want to query data this is still RESTful if you treat your request as the creation of a search result resource:
POST /search HTTP/1.1
your query-data
Your server should return the newly created resource in the Location header:
HTTP/1.1 201 Created
Location: /search/3
The result can still be cached and you can bookmark it or send the link. The downside is that you need an additional POST.