I'm not using EF, so have followed the NoDb sample to successfully load data from my WebApi without using the server side metadata. After the initial load, I was hoping to use the local data cache in the EntityManager while the user interacts with the page. The problem is when I call executeQueryLocally, the cached data set is empty. I stepped through the code to see why the data wasn't being saved to the cache, and there were two issues:
in _getEntityType, metadataStore.isEmpty() was returning true.
in _getEntityType, metadataStore._getEntityTypeNameForResourceName was returning nothing
To get around the this, I added calls in my code to metadataStore.addDataService and metadataStore._setEntityTypeForResourceName. After adding these, the cache was saved properly and executeQueryLocally worked. I'm assuming this was not the intended way to get this to work... Is there something else I am doing wrong? Or is this a bug that can be fixed?
Sorry for taking so long getting back to this one.
We just made the metadataStore.setEntityTypeForResourceName public in breeze v.1.1.3. ( we renamed the method to remove the first '_".
Otherwise, you did exactly the right thing. Good catch.
Related
Having an issue with the <distributed-cache> tag and Redis.
We have a <partial> Razor view that displays results of a long-running query. We acquire the data from a service injected in using #inject. The data updates very rarely, hence we wrap the content in a <distributed-cache> tag helper, with a long expires-after attribute.
However, when the data is finally updated (in another part of our app), we need to delete that key from the distributed cache, in order to force the page to update on next execution. (It's not possible for us to predict when the data will change - we can only respond to an external event.)
The problem we're having is that, despite having a fixed name attribute, the cache key appears to be impossible to predict. For example <distributed-cache name='_myQuery' vary-by-user='true'> creates a key something along the lines 7/za/Bc/ZRn/MsR/hG69TYTx1LEzqBvlyH1OLJgrpk4= in Redis.
How can I either:
Predict/calculate what the cache key is going to be in redis, so that I can delete it in another part of our application?;
Force the <distributed-cache> tag to ignore the cached value this one time? I know we have the enabled property, because this isn't going to work because the page doesn't know when to invalidate the cache.
After digging into the ASP.NET Core source I've found the CacheTagKey.cs file, which contains the GenerateKey() and GenerateHaskedKey() methods. These methods create the key from a bunch of params, then SHA256 hashes the key and returns base64.
So it looks like I can use this to predict the cache key and solve the issue.
It would appear that the savechanges method on breeze waits indefinitely when calling to or waiting for the server. Is there a way of getting it to time out? I am calling save change with allowConcurrentSaves: false. This now causes users who somehow do not get a response from the server to simply hang in limbo indefinitely say for example with a dropped internet connection.
I do not want to re-call the method with allowConcurrentSaves to false fearing that I might duplicate the data.
Any ideas?
Thanks
Update 16 May 2014
You can set HTTP-level timeout and cancellation with the AJAX Adapter's requestInterceptor as of v.1.4.12. See the documentation, "Controlling AJAX calls".
I'd still be reluctant to use this feature on save as you have no chance of knowing what whether the server persisted the data or not. Of course if your client hangs or crashes you don't know anyway. It's up to you.
Original Answer
Actually, there is a ready-made solution from Q.js. It's called timeout and it's mentioned in the API reference with a simplified example of its implementation and use in the readme.md.
I know you asked about Save but your question is pertinent for promises in general. Here is a query example adapted from the queryTests.js in our DocCode Sample
var timeoutMs = 10000; // 10 second timeout
var em = newEm(); // creates a new EntityManager
var query = new EntityQuery().from("Customers").using(em);
Q.timeout(query.execute, timeoutMs)
.then(queryFinishedBeforeTimeout)
.fail(queryFailedOrTimedout);
function queryFailedOrTimedout(error) {
var expect = /timed out/i;
var emsg = error.message;
if (expect.test(emsg)) {
log("Query timed out w/ message '{0}' " + expectTimeoutMsg)
.format(emsg));
// do something
} else {
handleFail(error);
}
}
Note: I just added this test so you'd have to get if from github or wait for a Breeze release after 1.2.5.
Oops ... maybe not
I gave what I think is a great answer for query. It may not be the right answer for save.
The problem with save is that you do not know on the client if the save succeeded until the server responds. Things could go wrong anywhere along the way. The server might not have heard the request to save. The server may have failed during save. The server may have saved the data but the response never made it back to the client.
Changing the value of allowConcurrentSaves won't get you out of this bind. Neither will having a save timeout.
In fact, adding a timeout to the save is probably deceiving. It is even possible for the save response to arrive after your custom timeout ... in which case Breeze will have tried to update your EntityManager ... and you won't know if Breeze succeeded or failed!
What if we added a Breeze save timeout. What should it do? What if breeze said the save had timedout ... and Breeze ignored a belated response from the server? Then imagine that the save succeeded on the server - it just took "too long" for it to respond to the client. Now you've got a client whose state is unexpectedly out of sync with the server. This is not good.
So I think you want a different solution to this very real problem. It's a user experience problem really. You can indicate to the user that you think the save is still in progress and then set your own timer. If the save isn't done when your timer expires, you can query the server to see if the data have been saved or if there is a connection ... or something along these lines. I can't think of a better way right now honestly.
Note that I'm assuming you need to know that the server succeeded. If you avoid store-generated IDs and always assume saves succeed unless the server tells you otherwise ... well that's a completely different paradigm and programming model that we could talk about someday (see meteorjs).
The net of all of this: I'm pretty darned sure that a save timeout is NOT what you want.
Still useful on a query though :)
Great question, and I wish I had a good answer. But it is definitely worth looking into. Could you please add this as a feature request to the Breeze User Voice. We take these requests very seriously in determining our priorities for Breeze development.
First time user long time reader. I have thoroughly looked for an explanation for the problem I'm having via the mighty search engine Google, but alas I have failed to produce any significant insight.
I need to be able to ensure that a model form is not reloaded with invalid data. Since the model stored in memory on the server is edited directly with the parameters of the web form first, and THEN checked for validity, without additional code invalid model data will ALWAYS be sent back to the form. This is less than desirable to me. My question is this: how do I ensure this doesn't happen?
What I'm thinking is I need some mechanism for saving the state of the object before it's modified with the parameters sent from the web form, and then after a failed validation restore the object to it's previous, correct and unmodified state of being.
Help!
Thanks,
Les
The object isn't actually modified in the db if validation fails, even though the object is in an invalid state in the form ... the thinking behind this is that the user wants to see the errors they made so they can correct them.
If you don't want that to be the case, then just read back the object with a WhateverObject.find(x) and assign it to the variable that the form is referencing and it will 'restore' the object to its previous unmodified state.
To add to what concept47 said you can also get the value for a particular field using
object.field_was
Have a look at ActiveRecord::Dirty for details (http://ar.rubyonrails.org/classes/ActiveRecord/Dirty.html)
Using that you could retrieve the original values for just those fields that had validation errors.
We have created a Custom List template programmatically using Feature.xml, Element.xml, Schema.xml AllItems.aspx, and 3 aspx forms. We have a code behind file for each of these aspx files. i.e. for the AllItems.aspx, DispForm.aspx, EditForm.aspx and NewForm.aspx.
Problematic file is AllItems.aspx. In the code behind for AllItems.aspx file we are deleting previous list items and adding new items to the list before showing them up to the user. As per expectations the code behind file for AllItems.aspx is derived from WebPartPage Class and we have tried to overload quite a few methods without much success.
Problem only occurs on the first time rendering i.e. when an instance of this list is created. When overriding OnLoad(), we get the Save conflict error, Similar is the case with OnInit(), CreateChildControls() method. However, when we override the Render() or RenderChildren() method no such error comes up but at the same time our new list items are also not visible. On browser refresh everything starts working fine as expected. It is only for the first time that the issue comes up.
What could be the possible cause for this? Any ideas, suggestions would be highly appreciated.
Best Regards,
Raghu
I had a problem with a custom EditForm.aspx. I have two lists that are linked together and a change in one causes an event handler to update the other. I have a custom control in EditForm.aspx that edits the linked list. This was causing the event handler to update the item displayed by EditForm.aspx. This in turn would cause the conflict error when the user saved the form.
I finally found that I could reset the context with:
SPContext.Current.ResetItem();
I am not sure if this will help in your case but it fixed my problem.
I'm facing a strange problem in my project. My actions are getting old param values instead of the actual values which are in Request.Params. I created a HomeController.Echo(string text) action to illustrate it (see screenshot). When I call the action for the first time like "Home/Echo?text=aaa" everything works fine. When I call the same action second time with different text value ("Home/Echo/text=bbb"), I get the old "aaa" value again in my action "text" parameter. Strange think is that Request.Params contains the right "bbb" value.
I'm thinking if there's something I could break myself, but can't figure out anything. I'm serving controllers from IoC container, I overrided ControllerActionInvoker.InvokeActionMethodWithFilters method (to inject dependencies into filters from IoC) and I'm handling HttpApplication.AuthenticateRequest. Im'not working with params/binding anyhow in any of these...
screenshot
The problem was caused by some threading issues probably - I forgot to register controllers in my IoC container with per-request lifecycle (they were registered as singletons).
Have you debugged through the application to see where the value is getting switched out. A simple watch on the text variable (whatever you call it in the code) should yield where the variable gets changed. Without code to run through, I have no clue where it is happening.
I would say write a test, but there is still a possibility of UI interfering here. If you find where in the code it is changing, then write a test to confirm the bug and start whacking at it.
I suggest you to start commenting all the methods you overrode until you isolate the problem. In worst case you will get to the point where the ASP.NET MVC wizard left your project when you created it and where parameter binding definitely worked.