I have noticed that crystal report runs the Linq query once again when the page index is changed, means when we load second page from first page?
So just wanted to know if we can get which page is loaded so that we can keep values in session.
Just a hint is required as I am not getting the desired results from Google.
Update:
I am sorry in a hurry I just clicked on a wrong tag.
So the problem is like:
This is my code below which I use fr running my crystal report:
var rpt = new Result();
List<class> lst1 = new DALMethod().Get();
rpt.SetDataSource(lst1);
CRReportViewer.ReportSource = rpt;
When I switch from page one to two or more, this method in DAL is called again taking the same time it took first time to load, so I just want to have the data in session when query runs first time, and next time when I get the page index, then I will show data from session.
Is there a way around by which I can get the page index in this c# code?
I had found the solution, hope this might help someone else:
I was using a generic list as a data source:
As soon as we get to know the page loads for the first time, I mean not a postback, we can initialize a list to be maintained in session.
After showing the report we can add the data source (which is a list type).
On Report page shift data will be taken from session.
if (!IsPostBack)
{
//clear session and create new session
Session["ReportGenericList"] = null;
}
List<class> datasourceLst=null;
if (Session["ReportGenericList"] != null)
{
datasourceLst= (List<class>)Session["ReportGenericList"];
}
else
{
datasourceLst = //call methods to fill datasource
Session["ReportGenericList"] = datasourceLst;
}
Related
I created PowerBI report which which is connecting to data source via API service. Returning json contains thousands of entities. API service is called via Web.Content function. API service returns always total record count and so we are able to calculate nr. of pages which has to be called to obtain whole dataset. This report is displaying data from our servicedesk app, which is deployed on many servers and for many customers and use Query parameters to connect to any of these servers.
Detail of Power query is below.
Why am I writing here. This report was working without any issue more than 1,5 year but on August 17th one of servers start causing erros in step Pages where are some random lines (pages) with errors - see attached picture labeled "Errors in step Pages". and this is reason that next step Entities (List.Union) in query is stopping refresh and generate errors with message:
Expression.Error: We cannot apply field access to the type List. Details: Value=[List] Key=requests
What is notable
API service si returning records in the same order but faulty lists are random when calling with same parameters
some times is refresh without any error
The same power query called on another server is working correctly , problem is only with one specific server.
This problem started without notice on the most important server after 1,5 year without any problem.
Here is full text power of query for this main source, which is used later in other queries to extract all necessary data. Json is really complicated and I extract from it list of requests, list of solvers, list of solver groups,.... and this base query and its output is input for many referenced queries.
Errors in step Pages
let
BaseAPIUrl = apiurl&"apiservice?", /*apiurl is parameter - name of server e.g. https://xxxx.xxxxxx.sk/ */
EntitiesPerPage = RecordsPerPage, /*RecordsPerPage is parameter and defines nr. of record per page - we used as optimum 200-400 record per pages, but is working also with 4000 record per page*/
ApiToken = FnApiToken(), /*this function is returning apitoken value which is returning value of another api service apiurl&"api/auth/login", which use username and password in body of call to get apitoken */
GetJson = (QParm) => /*definiton general function to get data from data source*/
let
Options =
[ Query= QParm,
Headers=
[
Accept="application/json",
ApiKeyName="apitoken",
Authorization=ApiToken
]
],
RawData = Web.Contents(BaseAPIUrl, Options),
Json = Json.Document(RawData)
in Json,
GetEntityCount = () => /*one times called function to get nr of records using GetJson, which is returned as a part of each call*/
let
QParm = [pp="1", pg="1" ],
Json = GetJson(QParm),
Count = Json[totalRecord]
in
Count,
GetPage = (Index) => /*repeatadly called function to get each page of json using GetJson*/
let
PageNr = Text.From(Index+1),
PerPage = Text.From(EntitiesPerPage),
QParm = [pg = PageNr, pp=PerPage],
Json = GetJson(QParm),
Value = Json[data][requests]
in Value,
EntityCount = List.Max({ EntitiesPerPage, GetEntityCount() }), /*setup of nr. of records to variable*/
PageCount = Number.RoundUp(EntityCount / EntitiesPerPage), /*setup of nr. of pages */
PageIndices = { 0 .. PageCount - 1 },
Pages = List.Transform(PageIndices, each GetPage(_) /*Function.InvokeAfter(()=>GetPage(_),#duration(0,0,0,1))*/), /*here we call for each page GetJson function to get whole dataset - there is in comment test with delay between getpages but was not neccessary*/
Entities = List.Union(Pages),
Table = Table.FromList(Entities, Splitter.SplitByNothing(), null, null, ExtraValues.Error)
I also tried another way of appending pages to list using List.Generate. This is also bringing random errors in list but
it is bringing possibility to transform to table in contrast with original way with using List.Transform, but other referenced queries are failing and contains on the last row errors
When I am exploring content of faulty page/list extracting it via Add as New Query there are always all record without any fail.....
Source = List.Generate( /*another way to generate list of all pages*/
() => [Page = 0, ReqPageData = GetPage(0) ],
each [Page] < PageCount,
each [ReqPageData = GetPage( [Page] ),
Page = [Page] + 1 ],
each [ReqPageData]
),
#"Converted to Table" = Table.FromList(Source, Splitter.SplitByNothing(), null, null, ExtraValues.Error), /*here i am able to generate table from list in contrast when is used List.Generate*/
#"Expanded Column1" = Table.ExpandListColumn(#"Converted to Table", "Column1"), /*here aj can expand list to column*/
#"Removed Errors" = Table.RemoveRowsWithErrors(#"Expanded Column1", {"Column1"}) /*here i try to exclude errors, but i dont know what happend and which records (if any) are excluded*/
Extracting errored page
and finnaly I am tottaly clueless not able to find the cause of this behavior on this specific server. I tested to call pages which are errored via POSTMAN, I discused this issue with author of API service and He also tried to call this API service with all parameters but server is returning every page OK, only Power query is not able to List.Transform ...
I will be grateful and appreciate any tips or advice or if somebody solved the same issue in the past ....
Kuby
No, each error line of list in step List.Transform coud by extracted as new query and there are all records from one page OK. hmmmm
Finnaly, problem described in this issue was caused by "corrupted" content of returning json. The provider of core system informed me that they found bug and after fixing on the side of servisdesk is everything OK again. I tried to find problem in Power query and problem was in servisdesk. :(
Can somebody please tell me how I can cache my webgrid results so that when I sort by column it doesn't re-run my stored procedure query every time?
When clicking on a column link to sort, the stored proc (which is a little slow) that populates the table/grid is re-executed every time and hits the database. Any caching tips and tricks would be greatly appreciated.
Thx!
Well inside the controller action which is invoking the method on your repository supposed to query the database you could check whether the cache already contains the results.
Here's a commonly used pattern:
public ActionResult Foo()
{
// Try fetching the results from the cache
var results = HttpContext.Cache["results"] as IEnumerable<MyViewModel>;
if (results == null)
{
// the results were not found in the cache => invoke the expensive
// operation to fetch them
results = _repository.GetResults();
// store the results into the cache so that on subsequent calls on this action
// the expensive operation would not be called
HttpContext.Cache["results"] = results;
}
// return the results to the view for displaying
return View(results);
}
I have a bit of linq to entities code in a web app. It basically keeps a count of how many times an app was downloaded. I'm worried that this might happen:
Session 1 reads the download count (eg. 50)
Session 2 reads the download count (again, 50)
Session 1 increments it and writes it to the db (database stores 51)
Session 2 increments it and writes it to the db (database stores 51)
This is my code:
private void IncreaseHitCountDB()
{
JTF.JTFContainer jtfdb = new JTF.JTFContainer();
var app =
(from a in jtfdb.Apps
where a.Name.Equals(this.Title)
select a).FirstOrDefault();
if (app == null)
{
app = new JTF.App();
app.Name = this.Title;
app.DownloadCount = 1;
jtfdb.AddToApps(app);
}
else
{
app.DownloadCount = app.DownloadCount + 1;
}
jtfdb.SaveChanges();
}
Is it possible that this could happen? How could I prevent it?
Thank you,
Fidel
Entity Framework, by default, uses an optimistic concurrency model. Google says optimistic means "Hopeful and confident about the future", and that's exactly how Entity Framework acts. That is, when you call SaveChanges() it is "hopeful and confident" that no concurrency issue will occur, so it just tries to save your changes.
The other model Entity Framework can use should be called a pessimistic concurrency model ("expecting the worst possible outcome"). You can enable this mode on an entity-by-entity basis. In your case, you would enable it on the App entity. This is what I do:
Step 1. Enabling concurrency checking on an Entity
Right-click the .edmx file and choose Open With...
Choose XML (Text) Editor in the popup dialog, and click OK.
Locate the App entity in the ConceptualModels. I suggest toggling outlining and just expanding tags as necessary. You're looking for something like this:
<edmx:Edmx Version="2.0" xmlns:edmx="http://schemas.microsoft.com/ado/2008/10/edmx">
<!-- EF Runtime content -->
<edmx:Runtime>
<!-- SSDL content -->
...
<!-- CSDL content -->
<edmx:ConceptualModels>
<Schema Namespace="YourModel" Alias="Self" xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation" xmlns="http://schemas.microsoft.com/ado/2008/09/edm">
<EntityType Name="App">
Under the EntityType you should see a bunch of <Property> tags. If one exists with Name="Status" modify it by adding ConcurrencyMode="Fixed". If the property doesn't exist, copy this one in:
<Property Name="Status" Type="Byte" Nullable="false" ConcurrencyMode="Fixed" />
Save the file and double click the .edmx file to go back to the designer view.
Step 2. Handling concurrency when calling SaveChanges()
SaveChanges() will throw one of two exceptions. The familiar UpdateException or an OptimisticConcurrencyException.
if you have made changes to an Entity which has ConcurrencyMode="Fixed" set, Entity Framework will first check the data store for any changes made to it. If there are changes, a OptimisticConcurrencyException will be thrown. If no changes have been made, it will continue normally.
When you catch the OptimisticConcurrencyException you need to call the Refresh() method of your ObjectContext and redo your calculation before trying again. The call to Refresh() updates the Entity(s) and RefreshMode.StoreWins means conflicts will be resolved using the data in the data store. The DownloadCount being changed concurrently is a conflict.
Here's what I'd make your code look like. Note that this is more useful when you have a lot of operations between getting your Entity and calling SaveChanges().
private void IncreaseHitCountDB()
{
JTF.JTFContainer jtfdb = new JTF.JTFContainer();
var app =
(from a in jtfdb.Apps
where a.Name.Equals(this.Title)
select a).FirstOrDefault();
if (app == null)
{
app = new JTF.App();
app.Name = this.Title;
app.DownloadCount = 1;
jtfdb.AddToApps(app);
}
else
{
app.DownloadCount = app.DownloadCount + 1;
}
try
{
try
{
jtfdb.SaveChanges();
}
catch (OptimisticConcurrencyException)
{
jtfdb.Refresh(RefreshMode.StoreWins, app);
app.DownloadCount = app.DownloadCount + 1;
jtfdb.SaveChanges();
}
}
catch (UpdateException uex)
{
// Something else went wrong...
}
}
You can prevent this from happenning if you only query the download count column right before you are about to increment it, the longer the time spent between reading and incrementing the longer the time another session has to read it (and later rewriting - wrongly - incremented number ) and thus messing up the count.
with a single SQL query :
UPDATE Data SET Counter = (Counter+1)
since its Linq To Entities,it means delayed execution,for another session to screw up the Count (increment the same base,losing 1 count there) it would have to try to increment the app.Download count i beleive between the two lines:
else
{
app.DownloadCount += 1; //First line
}
jtfdb.SaveChanges(); //Second line
}
thats means that the window for the change to occur, thus making the previous count old, is so small that for an application like this is virtually impossible.
Since Im no LINQ pro, i dont know whether LINQ actually gets app.DownLoadCount before adding one or just adds one through some SQL command, but in either case you shouldnt have to worry about that imho
You could easily test what would happen in this scenario - start a thread, sleep it, and then start another.
else
{
app.DownloadCount = app.DownloadCount + 1;
}
System.Threading.Thread.Sleep(10000);
jtfdb.SaveChanges();
But the simple answer is that no, Entity Framework does not perform any concurrency checking by default (MSDN - Saving Changes and Managing Concurrency).
That site will provide some background for you.
Your options are
to enable concurrency checking, which will mean that if two users download at the same time and the first updates after the second has read but before the second has updated, you'll get an exception.
create a stored procedure that will increment the value in the table directly, and call the stored procedure from code in a single operation - e.g. IncrementDownloadCounter. This will ensure that there is no 'read' and therefore no possibility of a 'dirty read'.
My main question here is dealing with the pramas map when having a one-to-many relationship managed within one dynamic form, as well as best practices for dealing with one-to-many when editing/updating a domain object through the dynamic form. The inputs for my questions are as follows.
I have managed to hack away a form that allows me to create the domain objects shown below in one Dynamic form, since there is no point in having a separate form for creating phone numbers and then assigning them to a contact, it makes sense to just create everything in one form in my application. I managed to implement something similar to what I have asked in my Previous Question (thanks for the people who helped out)
class Contact{
String firstName
String lastName
// ....
// some other properties
// ...
static hasMany = [phones:Phone]
static mapping = {
phones sort:"index", cascade: "all-delete-orphan"
}
}
class Phone{
int index
String number
String type
Contact contact
static belongsTo = [contact:Contact]
}
I basically managed to get the values from the 'params' map and parse them on my own and create the domain object and association manually. I.e. i did not use the same logic that is used in the default scaffolding, i.e.
Contact c = new Contact(params)
etc...., i just looped through all the params and hand crafted my domain objects and saved them and everything works out fine.
My controller has code blocks that look like this (this is stripped down, just to show a point)
//create the contact by handpicking params values
def cntct = new Contact()
cntct.firstName = params.firstName
cntct.lastName = params.lastName
//etc...
//get array of values for number,type
def numbers = params['phone.number']
def types = params['phone.type']
//loop through one of the arrays and create the phones
numbers.eachWithIndex(){ num, i ->
//create the phone domain object from
def phone = new Phone()
phone.number = num
phone.type = types[i]
phone.index = i
cntct.addToPhones(phone)
}
//save
My questions are as follows:
What is the best practice of handeling such a situation, would using Command objects work in this case, if yes where can i found more info about this, all the examples I have found during my search deal with one-to-one relationships, I couldn't find an example for one-to-many?
What is the best way to deal with the relatiohsips of the phones in this case, in terms of add/removing phones when editing the contact object. I mean the creation logic is simple since I have to always create new phones on save, but when dealing with updating a contact, the user might have removed a phone and/or editing an exiting one and/or added some new phones. Right now what I do is just delete all the phones a contact has and re-create them according to what was posted by the form, but I feel that's not the best way to do it, I also don't think looping over the existing ones and comparing with the posted values and doing a manual diff is the best way to do it either, is there a best practice on how to deal with this?
Thanks, hopefully the questions are clear.
[edit] Just for more information, phone information can be added and deleted dynamically using javascript (jquery) within the form [/edit]
disclaimer: i do not know if the following approach works when using grails. Let me know later.
See better way for dynamic forms. The author says:
To add LineItems I have some js that calculates the new index and adds that to the DOM. When deleting a LineItem i have to renumber all the indexes and it is what i would like to avoid
So what i do
I have a variable which stores the next index
var nextIndex = 0;
When the page is loaded, i perform a JavaScript function which calculates how many child The collection has and configure nextIndex variable. You can use JQuery or YUI, feel free.
Adding a child statically
I create a variable which store the template (Notice {index})
var child = "<div>"
+= "<div>"
+= "<label>Name</label>"
+= "<input type="text" name=\"childList[{index}].name\"/>"
+= "</div>"
+= "</div>"
When the user click on the Add child button, i replace {index} - by using regex - by the value stored in the nextIndex variable and increment by one. Then i add to the DOM
See also Add and Remove HTML elements dynamically with Javascript
Adding a child dinamically
Here you can see The Paolo Bergantino solution
By removing
But i think it is the issue grow up when deleting. No matter how many child you remove, does not touch on the nextIndex variable. See here
/**
* var nextIndex = 3;
*/
<input type="text" name="childList[0].name"/>
<input type="text" name="childList[1].name"/> // It will be removed
<input type="text" name="childList[2].name"/>
Suppose i remove childList1 What i do ??? Should i renumber all the indexes ???
On the server side i use AutoPopulatingList. Because childList1 has been removed, AutoPopulatingList handles it as null. So on the initialization i do
List<Child> childList = new AutoPopulatingList(new ElementFactory() {
public Object createElement(int index) throws ElementInstantiationException {
/**
* remove any null value added
*/
childList.removeAll(Collections.singletonList(null));
return new Child();
}
});
This way, my collection just contains two child (without any null value) and i do not need to renumber all the indexes on the client side
About adding/removing you can see this link where i show a scenario wich can gives you some insight.
See also Grails UI plugin
Thanks,
Your answer brought some insight for me to do a wider search and I actually found a great post that covers all the inputs in my question. This is just a reference for anyone reading this. I will write a blog entry on how I implemented my case soon, but this link should provide a good source of ino with a working exmaple.
http://www.2paths.com/2009/10/01/one-to-many-relationships-in-grails-forms/
Most of the time I use ajax to manage such problem.
So when the user clicks add new phone I get the template UI from the server for manageability purpose ( the UI just same GSP template that I use to edit, update the phone), so this way you are not mixing your UI with your js code, whenever you want to change the UI you have to deal only with our GSP code.
Then after getting the UI I add it to the page using jquery DOM manipulation. Then after filling the form when they hit add(save) the request is sent to the server via ajax and is persisted immediately.
When the user clicks edit phone the same UI template is loaded from the server filled with existing phone data, then clicking update will update the corresponding phone immediately via ajax, and same thing applies to delete operation.
But one day I got an additional scenario for the use case that says, "until I say save contact no phone shall be saved on the backend, also after adding phones to the contact on the ui if navigate away to another page and come back later to the contact page the phones I added before must be still there." ugh..
To do this I started using the Session, so the above operations I explained will act on the phone list object I stored on the session instead of the DB. This is simple perform all the operation on the phonesInSession but finally dont forget to do this(delete update):
phonesToBeDeleted = phonesInDB - phonesInSession
phonesToBeDeleted.each{
contact.removeFromPhones(it)
it.delete()
}
I know I dont have to put a lot of data in session but this is the only solution I got for my scenario.
If someone has got similar problem/solution please leave a comment.
First, in all your input fields names you add an #:
<input type="text" name="references[#].name"/>
Second, add call a function before submitting:
<g:form action="save" onsubmit="replaceAllWildCardsWithConsecutiveNumbers();">
Third, this is the code for the function that you call before submitting the form:
function replaceAllWildCardsWithConsecutiveNumbers(){
var inputs = $('form').find("[name*='#']");
var names = $.map(inputs, function(el) { return el.name });
var uniqueNames = unique(names);
for (index in uniqueNames) {
var uniqueName = uniqueNames[index];
replaceWildCardsWithConsecutiveNumbers("input", uniqueName);
replaceWildCardsWithConsecutiveNumbers("select", uniqueName);
}
}
function unique(array){
return array.filter(function(el, index, arr) {
return index === arr.indexOf(el);
});
}
function replaceWildCardsWithConsecutiveNumbers(inputName, name){
counter = 0;
$(inputName + "[name='" + name + "']").each(function (i, el) {
var curName = $(this).attr('name');
var newName = curName.replace("#", counter);
$(this).attr('name', newName);
counter += 1;
});
}
Basically, what the code for replaceAllWildCardsWithConsecutiveNumbers() does, is to create a list for all input (or select) elements whose name contains an #. Removes the duplicates. And then iterates over them replacing the # with a number.
This works great if you have a table and you are submitting the values to a command object's list when creating a domain class for the first time. If you are updating I guess you'll have to change the value of counter to something higher.
I hope this helps someone else since I was stuck on this issue for a while myself.
I'm working on an existing report and I would like to test it with the database. The problem is that the catalog set during the initial report creation no longer exists. I just need to change the catalog parameter to a new database. The report is using a stored proc for its data. It looks like if try and remove the proc to re-add it all the fields on the report will disapear and I'll have to start over.
I'm working in the designer in Studio and just need to tweak the catalog property to get a preview. I have code working to handle things properly from the program.
If you just need to do it in the designer then right click in some whitespace and click on Database->set datasource location. From there you can use a current connection or add a new connection. Set a new connection using the new catalog. Then click on your current connection in the top section and click update. Your data source will change. But if you need to do this at runtime then the following code is the best manner.
#'SET REPORT CONNECTION INFO
For i = 0 To rsource.ReportDocument.DataSourceConnections.Count - 1
rsource.ReportDocument.DataSourceConnections(i).SetConnection(crystalServer, crystalDB, crystalUser, crystalPassword)
Next
EDIT: Saw your edit, so i'll keep my original post but have to say.. I've never had a crystal report in design mode in VS so I can't be of much help there sorry.
report.SetDatabaseLogon(UserID, Password, ServerName, DatabaseName);
After that you have to roll through all referenced tables in the report and recurse through subreports and reset their logoninfo to one based on the reports connectioninfo.
private void FixDatabase(ReportDocument report)
{
ConnectionInfo crystalConnectionInfo = someConnectionInfo;
foreach (Table table in report.Database.Tables)
{
TableLogOnInfo logOnInfo = table.LogOnInfo;
if (logOnInfo != null)
{
logOnInfo.ConnectionInfo = crystalConnectionInfo;
table.LogOnInfo.TableName = table.Name;
table.LogOnInfo.ConnectionInfo.UserID = someConnectionInfo.UserID;
table.LogOnInfo.ConnectionInfo.Password = someConnectionInfo.Password;
table.LogOnInfo.ConnectionInfo.DatabaseName = someConnectionInfo.DatabaseName;
table.LogOnInfo.ConnectionInfo.ServerName = someConnectionInfo.ServerName;
table.ApplyLogOnInfo(table.LogOnInfo);
table.Location = someConnectionInfo.DatabaseName + ".dbo." + table.Name;
}
}
//call this method recursively for each subreport
foreach (ReportObject reportObject in report.ReportDefinition.ReportObjects)
{
if (reportObject.Kind == ReportObjectKind.SubreportObject)
{
this.FixDatabase(report.OpenSubreport(((SubreportObject)reportObject).SubreportName));
}
}
}