I'm at a loss with why this isn't working...
I have a .NET Core app using EF Core, and I'm making an Ajax call via jQuery to my controller to retrieve some data from the database via EF Core. Debugging the call via my developer tools in the browser (IE/Chrome) results in a status of failed/aborted. Yet when I step through my method in my controller, the method seems to be able to retrieve the data from the database via EF Core just fine.
Here's my controller:
public ActionResult GetInfo(string term)
{
using (var dbContext = new DatabaseContext())
{
// use DbContext to get data from the database
var retrievedData = dbContext.TableName.Where(...);
return Json(retrievedData.Select(data => new {
id = data.id,
text = data.text
}));
}
}
And here's the jQuery:
$(#element).select2({
...
ajax: {
url: $(#element).attr("data-getinfo"),
dataType: 'json', // tried this with jsonp and application/JSON with no luck
contentType: 'application/json; charset=utf-8',
delay: 250,
data: function (params) {
return: { term: params.term};
},
processResults: function (data) {
return {
results: $.map(data, function (item) {
return {
id: item.id, text: item.text
}
})
}
},
},
....
});
The Ajax calls work with previous apps I've worked on, but they used MVC 5 and EF 6. This also works if I retrieve dummy data, IE instead of using EF Core to get the data, I return fake data built into the controller. What gives?
To clarify the root of your problem: You are querying your database and returning an IEnumerable as a JsonResult. But first, you need to understand one step before. Calling .Where returns an IQueryable. You can think of an IQueryable as if it is a TSQL command that was not yet execute on the database. Only calls that will enumerate the results will trigger the materialization of the query.
So you did this:
// .Where returns an IQueryable. You can "chain" more wheres later.
// the query will still not be executed
var retrievedData = dbContext.TableName.Where(...);
// This then returns an IEnumerable to the client.
// The Select will materialize (execute) the query
return Json(retrievedData.Select(data => new {
id = data.id,
text = data.text
}));
The problem with your code is: .Select returns an IEnumerable which enumerates the results. But, by the time the browser or whatever client you are dealing with starts to enumerate the results, your database connection is already closed, because you used using block around your dbContext (which is kind of correct.. see comments in the end).
So, to fix it, you need basically to enumerate the results yourself or not close the connection (let the framework close for you when the request is finished..). This minor change fix the problem:
// ToList() will enumerate all the results in memory
var retrievedData = dbContext.TableName.Where(...).ToList();
Other comments:
You don't need (also shouldn't) manage the creation of the dbContext by yourself. You can register it in the DI container and the framework will do the rest for you. You can take a look in the EF Core docs to have an idea on how it is done.
Not an ideal solution, but I got it working. I suspect it might have to do with how .NET Core or EF Core was returning data to the browser, but I can't say for sure yet.
I ended up using Json.NET for a workaround. Performance isn't bad (I tried a query with hundreds of records and it only took a couple of seconds at most), and I was already using it for an external API call.
public ActionResult GetInfo(string term)
{
using (var dbContext = new DatabaseContext())
{
// use DbContext to get data from the database
var retrievedData = dbContext.TableName.Where(...);
var initJson = Json(retrievedData.Select(data => new {
id = data.id,
text = data.text
}));
var serializedJson = Newtonsoft.Json.JsonConvert.SerializeObject(initJson);
var deserializedJson = Newtonsoft.Json.JsonConvert.DeserializeObject(serializedJson);
return Json(deserializedJson);
}
}
So I have this lookback API request:
https://rally1.rallydev.com/analytics/v2.0/service/rally/workspace/xxxxxxx/artifact/snapshot/query.js?find={"ObjectID":92444754348,"__At":"2017-02-23T00:00:00Z"}&fields=true&start=0&pagesize=10&removeUnauthorizedSnapshots=true
How can I make that request using the Ext equivalent. I have tried many ways, including this one:
let snapshot = Ext.create('Rally.data.lookback.SnapshotStore', {
find: {
ObjectID: 92444754348,
__At: "2017-02-23T00:00:00Z"
}
});
return snapshot.load();
This example returns an object that has the field "raw", which to my understanding is supposed to have all the artifact's fields along with the values they had at the specified time. But, "raw" only has ObjectID, Project, _ValidFrom, and _ValidTo.
Right now I'm able to solve my issue by using an ajax GET request and parsing the JSON; but I would like to use the Ext solution instead (which seems to be the recommended one).
Thanks.
If you include a fetch in your config when you're creating the store it will autocreate the correct model for you.
let snapshot = Ext.create('Rally.data.lookback.SnapshotStore', {
find: {
ObjectID: 92444754348,
__At: "2017-02-23T00:00:00Z"
},
fetch: ['ObjectID'] //add all the fields you want here
});
fields=true is a nice shorthand to get all the data back, but the store/model have no idea how to interpret that...
The store also has config properties for compress, removeUnauthorizedSnapshots and most of the other parameters Lookback Api supports.
My wcf project returns the Countries List as json, in wcf project parse using Newtonsoft json. I get json in my client website built on mvc, i show the data using jtable plugin in jquery. The plugin failed to display because, the json contains /(back slashes).
Code to display jtable is
Name:{
title: 'Country Name',
width: '40%',
options: '/Country/Index'
}
Country/Index result is
{"Result":"OK","Options":"[{\"DisplayText\":\"India\",\"Value\":1},{\"DisplayText\":\"Singapore\",\"Value\":2}]"}
Country/Index gets the result from wcf service. Is there any way to strip the / in json.
Edit:
My wcf code is
List<JSONDisplayNameValue> lstLanguages = new List<JSONDisplayNameValue>();
//Get data from db.
//JSONDisplayNameValue has two variables DisplayName, Value
var json = JsonConvert.SerializeObject(lstLanguages);
return json;
Country/Index mvc code is
public JsonResult Index()
{
string Countries_list = processsvc.GetAllCountries();
return Json(new { Result = "OK", Options = Countries_list }, JsonRequestBehavior.AllowGet);
}
You are getting backslashes because you are double-serializing your data.
In your WCF code, you call JsonConvert.SerializeObject() to serialize your list of countries/languages to JSON before returning it.
In your MVC controller, you call your WCF service to get the list, which is already in JSON format. But then you add that JSON to another object and call Json() which causes the list to be serialized a second time. That is where the backslashes get added.
To fix this, you either need to
Deserialize the list you get back from your WCF service before adding it to the MVC result.
-- OR --
Make a way to retrieve your list of countries/languages without serializing it to JSON. Then add the unserialized list to your MVC result and serialize it as normal.
I'm very new to breeze/knockout, but I'm 99% of the way to doing what I need to do. I'm using the Hot Towel template, and I'm successfully retrieving a list of items via breeze. The entity (ITBAL) is a database first Entity Framework entity. When I look at the JSON coming back in Fiddler, I see the correct data. The problem is that all of the properties of data.results are dependentobservables, and not the raw values themselves.
We have a custom grid control that is trying to display the data.results array. Because it is not expecting observables, it is simply displaying "function dependentobservable" instead of the value.
I tried to unwrap the object, but keep getting the circular reference error. I don't know why that is, since ITBAL isn't associated with anything.
The data as Fiddler reports it:
[{"$id":"1","$type":"WebUIHtml5HotTowel.Models.ITBAL, WebUIHtml5HotTowel","IBITNO":"A100 ","IBWHID":"1 ","IBITCL":"50","IBITSC":"3 ","IBSUSP":" ","IBVNNO":"100 ","IBPRLC":" ","IBSCLC":" ","IBCCCD":"P","IBPICD":" ","IBSAFL":"Y","IBSTCS":399.99000,"IBUSCS":0.00000,"IBAVCS":414.95214,"IBLCST":7.00000,"IBLCCC":20.0,"IBLCDT":110923.0,"IBLSCC":20.0,"IBLSDT":130111.0,"IBLXCC":19.0,"IBLXDT":990102.0,"IBMXO1":2100.000,"IBMXO2":0.000,"IBMXO3":0.000,"IBMNO1":5.000,"IBMNO2":0.000,"IBMNO3":0.000,"IBFOQ1":0.000,"IBFOQ2":0.000,"IBFOQ3":0.000,"IBOHQ1":327.000,"IBOHQ2":0.000,"IBOHQ3":0.000,"IBAQT1":1576.000,"IBAQT2":0.000,"IBAQT3":0.000,"IBBOQ1":50.000,"IBBOQ2":0.000,"IBBOQ3":0.000,"IBPOQ1":448.000,"IBPOQ2":0.000,"IBPOQ3":0.000,"IBIQT1":1446.000,"IBIQT2":0.000,"IBIQT3":0.000,"IBRMD1":10.000,"IBRMD2":0.000,"IBRMD3":0.000,"IBRYD1":10.000,"IBRYD2":0.000,"IBRYD3":0.000,"IBISM1":0.000,"IBISM2":0.000,"IBISM3":0.000,"IBISY1":0.000,"IBISY2":0.000,"IBISY3":0.000,"IBAMD1":0.000,"IBAMD2":0.000,"IBAMD3":0.000,"IBAYD1":0.000,"IBAYD2":0.000,"IBAYD3":0.000,"IBMMD1":0.000,"IBMMD2":0.000,"IBMMD3":0.000,"IBMYD1":0.000,"IBMYD2":0.000,"IBMYD3":0.000,"IBSMD1":1.0,"IBSMD2":0.0,"IBSMD3":0.0,"IBSYD1":1.0,"IBSYD2":0.0,"IBSYD3":0.0,"IBBLME":335.000,"IBBLYO":2680.000,"IBBLLY":1441.000,"IBNMTY":8.0,"IBNMLY":11.0,"IBQSMD":21.000,"IBQSYD":21.000,"IBQSLY":20.000,"IBISMD":16318.19,"IBISYD":16318.19,"IBISLY":45714.87,"IBCSMD":373.46,"IBCSYD":373.46,"IBCSLY":67.00,"IBDQMD":0.000,"IBDQYD":0.000,"IBDQLY":0.000,"IBDSMD":0.00,"IBDSYD":0.00,"IBDSLY":0.00,"IBDCMD":0.00,"IBDCYD":0.00,"IBDCLY":0.00,"IBNOMD":18.0,"IBNOYD":18.0,"IBNOLY":18.0,"IBPKMD":15.0,"IBPKYD":15.0,"IBPKLY":14.0,"IBINUS":" ","IBIAID":0.0,"IBSAID":0.0,"IBCQT1":1527.000,"IBCQT2":0.000,"IBCQT3":0.000,"IBFCST":"Y","IBDRSH":" ","IBWMIU":"JP","IBFL15":" ","IBUS20":" ","IBLPR1":0.00000,"IBLPR2":0.00000,"IBLPR3":0.00000,"IBLPR4":0.00000,"IBLPR5":0.00000,"IBLPCD":" ","IBABCC":"B","IBPRCL":0.0,"IBQBCL":" ","IBACDC":"Y","IBTDCD":" ","IBDOUM":" ","IBTP01":0.0,"IBTP02":0.0,"IBTP03":0.0,"IBTP04":0.0,"IBLMCC":20.0,"IBLMDT":130513.0,"IBTMPH":"Y","IBCOMC":" ","IBCOMF":0.00000,"IBITCT":" ","IBEOQT":0.000,"IBITCM":0.0,"IBBRVW":" ","IBPTID":" ","IBQTLT":0.0000,"IBCTY1":"AUS","IBCTY2":"AUS","IBTXCD":"1","IBREVS":"Y","IBITXC":" ","IBMNOQ":0.000,"IBSTUS":0.000,"IBUS30":" ","IBPSLN":" ","IBPLIN":"N","IBUPDP":"Y","IBDFII":"2011-08-11T00:00:00.000","IBLHRK":"A","IBPLNC":" "}]
My Controller:
[BreezeController]
public class ItemInquiryController : ApiController
{
readonly EFContextProvider<AplusEntities> _contextProvider = new EFContextProvider<AplusEntities>();
[System.Web.Http.HttpGet]
public string Metadata()
{
return _contextProvider.Metadata();
}
[HttpGet]
public IQueryable<ITBAL> ItemBalances(string itemNumber, string warehouse)
{
return _contextProvider.Context.ITBALs.Where(i => i.IBITNO == itemNumber && i.IBWHID == warehouse)
.OrderBy(i => i.IBWHID)
.ThenBy(i => i.IBITNO);
}
}
The relevant portion from the viewmodel:
var manager = new breeze.EntityManager("api/ItemInquiry");
var store = manager.metadataStore;
var itbalInitializer = function (itbal) {
itbal.CompositeKey = ko.computed(function () {
return itbal.IBITNO() + itbal.IBWHID();
});
};
store.registerEntityTypeCtor("ITBAL", null, itbalInitializer);
var index = "0" + (args.pageNum * args.pageSize);
var query = new breeze.EntityQuery("ItemBalances")
.withParameters({ itemNumber: "A100", warehouse: "1" })
.take(args.pageSize);
if (index > 0) {
query = query.skip(index);
}
manager.executeQuery(query).then(function (data) {
vm.itbals.removeAll();
var itbals = data.results;//[0].Data;
itbals.forEach(function (itbal) {
vm.itbals.push(itbal);
});
vm.totalRecords(1);
itemBalancesGrid.mergeData(vm.itbals(), args.pageNum, parseInt(vm.totalRecords()));
}).fail(function (e) {
logger.log(e, null, loggerSource, true, 'error');
});
I figure I must be missing something fairly simple, but it is escaping me.
UPDATE: I removed the BreezeController attribute from the ApiController, and it works correctly.
Jon, removing the [Breeze] attribute effectively disables breeze for your application so I don't think that is the long term answer to your problem.
If you don't actually want entities for this scenario - you just want data - than a Breeze projection that mentions just the data to display in the grid would seem to be the best choice. Projections return raw data that are not wrapped in KO observables and are not held in the Breeze EntityManager cache.
If you want the data as cached entities and you also want to display them in a grid that doesn't like KO observable properties ... read on.
You can unwrap a KO'd object with ko.toJS. However, the grid is likely to complain about circular references (or throw an "out of memory" exception as some grids do) ... even if the entity has no circular navigation paths. The difficulty stems from the fact that every Breeze entity has an inherent circularity by way of its entityAspect property:
something.entityAspect.entity //'entity' points back to 'something'
Because you are using Knockout for your model library and because you say ITBAL has no navigation properties ("is not related to anything"), I think the following will work for you:
manager.executeQuery(query).then(success) ...
function success(data) {
var unwrapped = ko.toJS(data.results).map(
function(entity) {
delete entity.entityAspect;
return entity;
});
vm.itbals(unwrapped);
vm.totalRecords(1); // huh? What is that "parseInt ..." stuff?
itemBalancesGrid.mergeData(vm.itbals(), args.pageNum, parseInt(vm.totalRecords()));
})
ko.toJS is a Knockout function that recursively unwraps an object or collection of objects, returning copies of values. Then we iterate over the copied object graphs, deleting their entityAspect properties. The array of results is stuffed into the vm.itbals observable and handed along.
You can imagine how to generalize this to remove anything that is giving you trouble.
Extra
What the heck is vm.totalRecords? I sense that this is supposed to be the total number of matching records before paging. You can get that from Breeze by adding .inlineCount() to the breeze query definition. You get the value after the query returns from the data.inlineCount property.
Do you really need vm.itbals()? If all you do here is pass values to the grid, why not do that and cut out the middle man?
The following success callback combines these thoughts
function success(data) {
var unwrapped = ko.toJS(data.results).map(
function(entity) {
delete entity.entityAspect;
return entity;
});
itemBalancesGrid.mergeData(unwrapped, args.pageNum, data.inlineCount);
})
Using Restlet 2.1 for Java EE, I am discovering an interesting problem with its ability to handle attributes.
Suppose you have code like the following:
cmp.getDefaultHost().attach("/testpath/{attr}",SomeServerResource.class);
and on your browser you provide the following URL:
http://localhost:8100/testpath/command
then, of course, the attr attribute gets set to "command".
Unfortunately, suppose you want the attribute to be something like command/test, as in the following URL:
http://localhost:8100/testpath/command/test
or if you want to dynamically add things with different levels, like:
http://localhost:800/testpath/command/test/subsystems/network/security
in both cases the attr attribute is still set to "command"!
Is there some way in a restlet application to make an attribute that can retain the "slash", so that one can, for example, make the attr attribute be set to "command/test"? I would like to be able to just grab everything after testpath and have the entire string be the attribute.
Is this possible? Someone please advise.
For the same case I usually change the type of the variable :
Route route = cmp.getDefaultHost().attach("/testpath/{attr}",SomeServerResource.class);
route.getTemplate().getVariables().get("attr") = new Variable(Variable.TYPE_URI_PATH);
You can do this by using url encoding.
I made the following attachment in my router:
router.attach("/test/{cmd}", TestResource.class);
My test resource class looks like this, with a little help from Apache Commons Codec URLCodec
#Override
protected Representation get() {
try {
String raw = ResourceWrapper.get(this, "cmd");
String decoded = new String(URLCodec.decodeUrl(raw.getBytes()));
return ResourceWrapper.wrap(raw + " " + decoded);
} catch(Exception e) { throw new RuntimeException(e); }
}
Note my resource wrapper class is simply utility methods. The get returns the string of the url param, and the wrap returns a StringRepresentation.
Now if I do something like this:
http://127.0.0.1/test/haha/awesome
I get a 404.
Instead, I do this:
http://127.0.0.1/test/haha%2fawesome
I have URLEncoded the folder path. This results in my browser saying:
haha%2fawesome haha/awesome
The first is the raw string, the second is the result. I don't know if this is suitable for your needs as it's a simplistic example, but as long as you URLEncode your attribute, you can decode it on the other end.