I am trying to sort a Vaadin Grid with a back end data source.
However, I want to sort on the outcome of a comparator method, not on a property of the back end data source. This is how the column is added to the table:
grid.addColumn(p -> p.getNumberOfChoices()).setHeader("Choices").setComparator((c1, c2) -> c1.getNumberOfChoices().compareTo(c2.getNumberOfChoices())).setSortable(true);
It appears that I must apply the setSortProperty() method to have the grid sort to attempt a sort, but since I do not have a class property for this sort, this results in an exception.
It is only possible to sort based on a comparator if all items are loaded into memory. This does defeat the purpose of using a lazy loading data provider. This means that you have two options:
Load all items into e.g a List and set them using Grid::setItems instead of using a lazy loading data provider.
Implement your data provider to have explicit support for whatever string you pass to setSortProperty(). The provider implementation can access the property string through Query::getSortOrders. In cases like this, you probably need to implement it to explicit check for that case to make it do a custom SQL query or similar to lazy load items in the desired way.
Related
I have a problem where I need to select a specific value from a specific entity from a entity set, however, I need to do it in a way without knowing the key.
This is the query I actually need:
odata/..../picklistLabels(locale='en_GB',optionId=10819)/label
However I need to program it in a way so it automatically selects the label without knowing the optionId. Is there a way to do this in OData?
From your question, I think that you want to perform a navigation but you don't have a key. Unfortunately, this exact functionality isn't available, however, you can perform an expand like this:
odata/..../picklistLabels?$filter=locale eq 'en_GB' and optionId=10819&$expand=label
This will get you the same information that the other call would do but in a slightly different format, you would have to find the first element in the array and then get the label property to get that information
As an aside, if you have the option to change the server (I'm guessing not due to the sapui5 tag but it might be useful for other users) you could change the key. If the locale and the optionId are enough to identify the object, then you could make these into a composite key. Here is a link for an example within the WebAPI OData source code: https://github.com/OData/ODataSamples/tree/master/WebApi/v4/ODataCompositeKeySample
Dear SAPUI5 Developers,
I developed a SAPUI5 Fiori Worklist project by using WebIDE template projects.
In the Component.js file the OData model has been fetched.
var sServiceUrl = this.getMetadata().getManifestEntry("sap.app").dataSources.mainService.uri;
var oModel = new sap.ui.model.odata.ODataModel(sServiceUrl, {
json: true,
loadMetadataAsync: true
});
oModel.attachMetadataFailed(function() {
// Call some functions from APP controller to show suitable message
}, this);
this.setModel(oModel, "BrandSet");
This part of code causes a call to OData server to fetch data from the remote server.
Now I want to order the data in backend and then receive the data. Assume the sorting function has been implemented correctly in the backend.
Thus, if I use $orderby=name or $orderby=price it has to be sorted by name or price respectively.
In some toturial they said for ordering use sorter option inside of the XML view file. Like here:
https://sapui5.hana.ondemand.com/#docs/guide/c4b2a32bb72f483faa173e890e48d812.html
Now my questions are:
How to apply this sorting inside of the Component.js file where the Model is initiated?
The second question is how to apply this ordering when we apply a filter to the model? Like the example that in the following link applied filter:
https://sapui5.hana.ondemand.com/#docs/guide/5295470d7eee46c1898ee46c1b9ad763.html
In fact I am looking for a function or any kind of method that add the $orderby=xxx to the OData service call.
I found a way here: https://sapui5.hana.ondemand.com/docs/api/symbols/sap.ui.model.odata.ODataModel.html#constructor
If I use mParameters.serviceUrlParams then I can add some URL parameter to the service request but it has been said "these parameters will be attached to all requests". Does it mean if I add the $orderbywith this method then I can not get rid of that in the further requests on that data model for example for filtering?
An app would normally be structured a bit differently to what you propose. The general assumption is that there is a lot of data available from the backend and to load all this data at once can cause performance problems, particularly when used over a mobile phone network. Furthermore, the data is an oData Entity Set, that is, a list of many items of the same type, so the data would be presented in the UI with a list or table.
Typically the app would then show the data in some kind of list, such as sap.m.List or sap.m.Table. These controls are designed to work with large volumes of data and would load initially the first 20 items from the entity set. Only when the user scrolls down the list of data would additional items be loaded. Also, with these controls the user can decide to sort or filter the data according to certain fields in your data.
Assuming that your app is work like this, here is the standard approach.
The Main model (as defined in the manifest) would not be loaded in Component.js, but loaded via the binding defined in the xml views of the app. In the views you could define a fixed sort and/or filter in the binding or you could allow the user to set the sort and filter criteria. This would be handled programmatically in the respective controllers. Normally the changes that the user makes to the sort and filter would be applied separately. For example, he/she chooses an new sort order, the oData is reread and the new sort order shown in the UI. Then the user may chose a filter criteria, and this is applied too. Of course, in your programming logic in the controllers you would need to have applied any default sort and filter criteria and then maybe combine or replace these with the criteria selected by the user.
To see an example of this, I would suggest to look at the Template Application “SAP Fiori Master-Detail Application” in the WebIDE.
As a complete novice programmer I am trying to populate my neo4j DB with data from heterogeneous sources. For this I am trying to use the Neo4jClient C# API. The heterogeneity of my data comes from a custom, continuously evolving DSL/DSML/metamodel that defines the possible types of elements, i.e. models, thus creating classes for each type would not be ideal.
As I understand, my options are the following:
Have a predefined class for each type of element: This way I can easily serialize my objects that is if all properties are primitive types or arrays/lists.
Have a base class (with a Dictionary to hold properties) that I use as an interface between the models that I'm trying to serialize and neo4j. I've seen an example for this at Can Neo4j store a dictionary in a node?, but I don't understand how to use the converter (defined in the answer) to add a node. Also, I don't see how an int-based dictionary would allow me to store Key-Value pairs where the keys (that are strings) would translate to Property names in neo4j.
Generate a custom query dynamically, as seen at https://github.com/Readify/Neo4jClient/wiki/cypher#manual-queries-highly-discouraged. This is not recommended and possibly is not performant.
Ultimately, what I would like to achieve is to avoid the need to define a separate class for every type of element that I have, but still be able to add properties that are defined by types in my metamodel.
I would also be interested to somehow influencing the serializer to ignore non-compatible properties (similarly to XmlIgnore), so that I would not need to create a separate class for each class that has more than just primitive types.
Thanks,
J
There are 2 problems you're trying to solve - the first is how to program the C# part of this, the second is how to store the solution to the first problem.
At some point you'll need to access this data in your C# code - unless you're going fully dynamic you'll need to have some sort of class structure.
Taking your 3 options:
Please have a look at this question: neo4jclient heterogenous data return which I think covers this scenario.
In that answer, the converter does the work for you, you would create, delete etc as before, the converter just handles the IDictionary instance in that case. The IDictionary<int, string> in the answer is an example, you can use whatever you want, you could use IDictionary<string, string> if you wanted, in fact - in that example, all you'd need to do would be changing the IntString property to be an IDictionary<string,string> and it should just work.
Even if you went down the route of using custom queries (which you really shouldn't need to) you will still need to bring back objects as classes. Nothing changes, it just makes your life a lot harder.
In terms of XmlIgnore - have you tried JsonIgnore?
Alternatively - look at the custom converter and get the non-compatible properties into your DB.
In the cache, I've got an Entity of type 'Mandate'.
Then I run the following code to fetch a collection of MandateHistory entities, which is then merged by breeze to the corresponding property of the Mandate entity :
function getMandatHistory(mandatId) {
var query = breeze.EntityQuery.from("MandatesHistory")
.where("Mandate.Id", "==", mandatId).orderBy("Id")
.expand("Mandate").skip(offset).take(pageSize).inlineCount(true);
return manager.executeQuery(query.using(service));
}
Note the orderBy clause is respected and the results are properly sorted by Id.
However the items in the collection property of the Mandate entity is NOT sorted. Do I have to do something special here ?
Sorting of the values returnd by collection navigation properties is NOT something that Breeze does. It will sort the results of a query, but if you want to sort, ( and keep sorted), one of the collection properties of an entity you will need to manage that yourself.
I think your best two options are either.
1) Sort before display. i.e. call a sort method on any collection right before you display it. Depending on what MVVM framework you are using, there is often a 'binding' that does exactly this.
2) Subscribe to the Breeze arrayChanged event on the array returned by your navigation property and call sort on the array anytime you see the change event. Note this can get expensive if you subscribe to a lot properties on a lot of entities.
I have an aggregated data view in an MVC project which displays the totals per month broken down by audit status. The controller code sets this up using a simple LINQ projection into an anonymous object like this:
From audits In db.Audits
Group By key = audits.DateCreated.Value.Month Into g = Group
Select New With {
.Month = key,
.Assigned = g.Sum(AuditsWithStatus(AuditStatus.Issued)),
.Unassigned = g.Sum(AuditsWithStatus(AuditStatus.Pending)),
.Closed = g.Sum(AuditsWithStatus(AuditStatus.Closed)),
.Cancelled = g.Sum(AuditsWithStatus(AuditStatus.Cancelled))
}
I know this is one of the big advantages of LINQ (using anonymous types), but I don't like losing the strong typing in the view (ie #ModelType SomeStrongType). Is there any general advice on this? Articles, blogs, or other places that deal with the issue and when to use which?
You cannot do anything with anonymous types outside of the scope of your method. You cannot return them to your view for example. In those cases you have to use a known type.
I use anonymous types when I am selecting data that I am then processing in another way. For example, selecting some bespoke data out of 1 source using Linq, and putting to put into another source.
If you are returning aggregate data such as an IEnumerable<IGrouping<TKey, TValue>> and TKey and TValue are anonymous types (you can group by anonymous types if you want); then you would not want to create 2 classes for TKey and TValue, where TKey has an overridden Equals and GetHashCode so you can group by it. And then do nothing more than read some values from it and throw it away, never to be re-used.
TLDR; use them when there is no need to create a known type to store your results. If you need to pass your results to somewhere outside the scope of the method, then you will need a type.
General advice is simple: always create dedicated viewmodel type for your views. In your case it would be pretty simple, containing exactly the properties you have in you anonymous class.
I understand that it seems like an unneeded overhead, but it'll make your code more readable and verifiable.