http://www.windowsazure.com/en-us/develop/mobile/tutorials/get-started-with-data-dotnet/#update-app
I'm the beginner of WP8, and I follow the above tutorial to create a mobile service that
I can insert/update/delete/query the tables in the cloud.
My question is, in the Query function (RefreshToDoItem):
private void RefreshTodoItems()
{
// This query filters out completed TodoItems.
items = todoTable
.Where(todoItem => todoItem.Complete == false)
.ToCollectionView();
ListItems.ItemsSource = items;
}
The "items" is a MobileServiceCollectionView object which can be used as a data source to display in a container.
But how can I retrive one of these result - I mean the data of a specific "field / column" that I can used for other purposes ??
Thanks a lot!
You can use the other methods of the query object, such as ToListAsync or ToEnumerableAsync, and get the data from there:
// This query filters out completed TodoItems.
items = await todoTable
.Where(todoItem => todoItem.Complete == false)
.ToListAsync();
var firstItem = items.First();
var text = firstItem.Text;
Related
I have figured out how to run a Google App Script project/function on a form submit using the information at https://developers.google.com/apps-script/guides/triggers/events#form-submit_4.
Once I have e I can call e.response to get a FormResponse object and then call getItemResponses() to get an array of all of the responses.
Without iterating through the array and checking each one, is there a way to find the ItemResponse for a specific question?
I see getResponseForItem(item) but it looks like I have to somehow create an Item first?
Can I some how use e.source to get the Form object and then find the Item by question, without iterating through all of them, so I could get the Item object I can use with getResponseForItem(item)?
This is the code I use to pull the current set of answers into a object, so the most current response for the question Your Name becomes form.yourName which I found to be the easiest way to find responses by question:
function objectifyForm() {
//Makes the form info into an object
var myform = FormApp.getActiveForm();
var formResponses = myform.getResponses()
var currentResponse = formResponses[formResponses.length-1];
var responseArray = currentResponse.getItemResponses()
var form = {};
form.user = currentResponse.getRespondentEmail(); //requires collect email addresses to be turned on or is undefined.
form.timestamp = currentResponse.getTimestamp();
form.formName = myform.getTitle();
for (var i = 0; i < responseArray.length; i++){
var response = responseArray[i].getResponse();
var item = responseArray[i].getItem().getTitle();
var item = camelize(item);
form[item] = response;
}
return form;
}
function camelize(str) {
str = str.replace(/[\.,-\/#!$%\^&\*;:{}=\-_`~()#\+\?><\[\]\+]/g, '')
return str.replace(/(?:^\w|[A-Z]|\b\w|\s+)/g, function(match, index) {
if (+match === 0) return ""; // or if (/\s+/.test(match)) for white spaces
return index == 0 ? match.toLowerCase() : match.toUpperCase();
});
}
//Use with installable trigger
function onSubmittedForm() {
var form = objectifyForm();
Logger.log(form);
//Put Code here
}
A couple of important things.
If you change the question on the form, you will need to update your
code
Non required questions may or may not have answers, so check if answer exists before you use it
I only use installable triggers, so I know it works with those. Not sure about with simple triggers
You can see the form object by opening the logs, which is useful for finding the object names
I have min 100 000 data into a Job_Details table and I'm using Entity Framework to map the data.
This is the code:
public GetJobsResponse GetImportJobs()
{
GetJobsResponse getJobResponse = new GetJobsResponse();
List<JobBO> lstJobs = new List<JobBO>();
using (NSEXIM_V2Entities dbContext = new NSEXIM_V2Entities())
{
var lstJob = dbContext.Job_Details.ToList();
foreach (var dbJob in lstJob.Where(ie => ie.IMP_EXP == "I" && ie.Job_No != null))
{
JobBO job = MapBEJobforSearchObj(dbJob);
lstJobs.Add(job);
}
}
getJobResponse.Jobs = lstJobs;
return getJobResponse;
}
I found to this line is taking about 2-3 min to execute
var lstJob = dbContext.Job_Details.ToList();
How can i solve this issue?
To outline the performance issues with your example: (see inline comments)
public GetJobsResponse GetImportJobs()
{
GetJobsResponse getJobResponse = new GetJobsResponse();
List<JobBO> lstJobs = new List<JobBO>();
using (NSEXIM_V2Entities dbContext = new NSEXIM_V2Entities())
{
// Loads *ALL* entities into memory. This effectively takes all fields for all rows across from the database to your app server. (Even though you don't want it all)
var lstJob = dbContext.Job_Details.ToList();
// Filters from the data in memory.
foreach (var dbJob in lstJob.Where(ie => ie.IMP_EXP == "I" && ie.Job_No != null))
{
// Maps the entity to a DTO and adds it to the return collection.
JobBO job = MapBEJobforSearchObj(dbJob);
lstJobs.Add(job);
}
}
// Returns the DTOs.
getJobResponse.Jobs = lstJobs;
return getJobResponse;
}
First: pass your WHERE clause to EF to pass to the DB server rather than loading all entities into memory..
public GetJobsResponse GetImportJobs()
{
GetJobsResponse getJobResponse = new GetJobsResponse();
using (NSEXIM_V2Entities dbContext = new NSEXIM_V2Entities())
{
// Will pass the where expression to be DB server to be executed. Note: No .ToList() yet to leave this as IQueryable.
var jobs = dbContext.Job_Details..Where(ie => ie.IMP_EXP == "I" && ie.Job_No != null));
Next, use SELECT to load your DTOs. Typically these won't contain as much data as the main entity, and so long as you're working with IQueryable you can load related data as needed. Again this will be sent to the DB Server so you cannot use functions like "MapBEJobForSearchObj" here because the DB server does not know this function. You can SELECT a simple DTO object, or an anonymous type to pass to a dynamic mapper.
var dtos = jobs.Select(ie => new JobBO
{
JobId = ie.JobId,
// ... populate remaining DTO fields here.
}).ToList();
getJobResponse.Jobs = dtos;
return getJobResponse;
}
Moving the .ToList() to the end will materialize the data into your JobBO DTOs/ViewModels, pulling just enough data from the server to populate the desired rows and with the desired fields.
In cases where you may have a large amount of data, you should also consider supporting server-side pagination where you pass a page # and page size, then utilize a .Skip() + .Take() to load a single page of entries at a time.
Our current system is using Lazyloading by default (it is something I am going to be disabling but it can't be done right now)
For this basic query I want to return two tables, CustomerNote and Note.
This is my query
using (var newContext = new Entities(true))
{
newContext.Configuration.LazyLoadingEnabled = false;
var result = from customerNotes in newContext.CustomerNotes.Include(d=>d.Note)
join note in newContext.Notes
on customerNotes.NoteId equals note.Id
where customerNotes.CustomerId == customerId
select customerNotes;
return result.ToList();
}
My result however only contains the data in the CustomerNote table
The linked entities Customer and Note are both null, what am I doing wrong here?
I got it working with the following which is much simpler than what I've found elsewhere
Context.Configuration.LazyLoadingEnabled = false;
var result = Context.CustomerNotes.Where<CustomerNote>(d => d.CustomerId == customerId)
.Include(d=>d.Note)
.Include(d=>d.Note.User);
return result.ToList();
This returns my CustomerNote table, related Notes and related Users from the Notes.
That is callled eager loading you want to achieve.
var customerNotes = newContext.CustomerNotes.Include(t=> t.Node).ToList();
This should work, i don't really understand the keyword syntax.
If the code above doesn't work try this:
var customerNotes = newContext.CustomerNotes.Include(t=> t.Node).Select(t=> new {
Node = t.Node,
Item = t
}).ToList();
I am trying to query records from the DB using Entity Framework. I need to get the total count of records as well as the actual records. What is the best approach to do this
public IEnumerable<mFeedback> RetrieveAll(QueryOptions qOptions)
{
if (qOptions == null)
throw new ArgumentNullException(nameof(qOptions));
using (_db)
{
var feedback = _db.Feedbacks
.Where(f => f.isDeleted == false);
if (qOptions.GetCount)
qOptions.TotalRecordsCount = feedback.Count();
feedback = feedback.OrderBy(string.IsNullOrWhiteSpace(qOptions.Sort) ? nameof(eFeedback.CreatedDate) : qOptions.Sort)
.Skip(qOptions.Skip)
.Take(qOptions.PageSize);
return _mapper.Map<IEnumerable<eFeedback>, IEnumerable<mFeedback>>(feedback.ToList());
}
}
The current code i have is shown above. This produces 2 hits on the DB. Is there a better approach?
Thanks in advance
A newbie question. I am using EntityFramework 4.0. The backend database has a function that will return a subset of records based on time.
Example of working code is:
var query = from rx in context.GetRxByDate(tencounter,groupid)
select rx;
var result = context.CreateDetachedCopy(query.ToList());
return result;
I need to verify that a record does not exist in the database before inserting a new record. Before performing the "Any" filter, I would like to populate the context.Rxes with a subset of the larger backend database using the above "GetRxByDate()" function.
I do not know how to populate "Rxes" before performing any further filtering since Rxes is defined as
IQueryable<Rx> Rxes
and does not allow "Rxes =.. ". Here is what I have so far:
using (var context = new EnityFramework())
{
if (!context.Rxes.Any(c => c.Cform == rx.Cform ))
{
// Insert new record
Rx r = new Rx();
r.Trx = realtime;
context.Add(r);
context.SaveChanges();
}
}
I am fully prepared to kick myself since I am sure the answer is simple.
All help is appreciated. Thanks.
Edit:
If I do it this way, "Any" seems to return the opposite results of what is expected:
var g = context.GetRxByDate(tencounter, groupid).ToList();
if( g.Any(c => c.Cform == rx.Cform ) {....}