Hi I am working on a Hotel Reservation Project in ASP.NET.
I want to make a filter so that I can search the room available by date (for example between 1 June and 5 June) and after that reserve that room .How can I do to change status of that room to "not available" for that period,so that somebody who want to reserve that room between 15 may and 30 may can do it.Status of the room is boolean value in my database.
try something like this
before displaying data on UI, you have to manipulate your room table everytime
var objrum = rum.toList().asQueryable(); // fetches all the rooms
var objreservation = reservation.toList().asQueryable(); // fetches all reservation
foreach(var res in objreservation)
{
foreach(var rum in objrum)
{
if(res.roomid == rum.rumid)
{
if(res.checkindate >= currentcheckindate && res.checkoutdate <= currentcheckoutdate)
{
rum.status = false // set to unavailable
}
else
rum.status = true // set to available
}
}
}
than fetch the data from room table for displaying on your UI
The 'Status' value changes and is based upon multiple things so you shouldnt really store it against your room table.
What you need to do in this case is write a query that looks at a date range and then returns the status based on your reservations table. So a user selects a date range and the query gets executed and returns a list of all the days with the status of available or booked.
Imagine if you did this
SELECT * FROM Reservation res LEFT JOIN Room ON res.Room_ID = Room.RoomId
Your room table has a status of Available so it will always return available for every single row. If you had this status as unavailable it would return unavailable for every row, even when the room was actually available.
Related
I have a Google drive table data source which stores list of open positions. Now in the data source I've set "Query per size" field to 10 so that I can get 10 records per page. I've added a Pager as well to show pagination.
My query is I want to display like "Page 1 of X" to my end users and this X will vary based on certain search filters. What will the best way to achieve this in Appmaker?
I've tried counting total records in a data source as per below code but every time updating that with the search criteria and recounting it is not a proper solution.
//Server side
var newQuery = app.models.Company.newQuery();
var records = newQuery.run();
var totalCount =0;
for(var i=0;i<records.length;i++)
{
totalCount=totalCount+1;
}
return totalCount;
In case you don't have any filters in your table your server code can be as simple as
// Server script
function getPagesCount(pageSize) {
var recordsCount = app.models.MyModel.newQuery().run().length;
var pagesCount = Math.ceil(recordsCount / pageSize);
return pagesCount;
}
As an alternative you can consider creating Calculated Model with a single field PagesCount.
In case you have some filters associated with the table then you'll need to run the query for the pages number with exact same filters.
Most likely the entire setup will not work effectively with Drive Tables since there is no way to query records number without querying records themselves. With Cloud SQL data backend one can create Calculated SQL Model with lightweight native SQL query (here :PageSize is query parameter which should be equal to the query.limit of the actual datasource):
SELECT
Ceil(COUNT(1) / :PageSize) AS RecordsNumber
FROM
TableName
WHERE
...
I've achieved this using Calculated Model as suggested by Pavel.
Steps :
Create a calculated data source with one field count.
In that data source add one parameter searchQuery. This will contain users filter going forward. Currently I have only one search query in which user can search many things. So I've added one parameter only.
In this data source add following server script.
Code:
// Server script
function getTotalRecords(query) {
var receivedQuery = query.parameters.searchQuery;
// console.log('Received query:' + query.parameters.searchQuery);
var records = app.models.Company.newQuery();
records.parameters.SearchText = query.parameters.searchQuery;
if(receivedQuery !== null) {
records.where = '(Name contains? :SearchText or InternalId contains? ' +
':SearchText or LocationList contains? :SearchText )';
}
var recordsCount = records.run().length;
var calculatedModelRecords = [];
var draftRecord = app.models.RecordCount.newRecord();
draftRecord.count = ''+recordsCount;
calculatedModelRecords.push(draftRecord);
return calculatedModelRecords;
}
.
On the Appmaker page bind a label with this data source.
On search query/your filter applied event add following code which Reload this data source and assign value to Parameter.
// Client script
function updateRecordCount(newValue) {
var ds = app.datasources.RecordCount;
ds.query.parameters.searchQuery = newValue;
ds.unload();
ds.load();
}
I'm using Azure Mobile App with Xamarin.Forms to create an offline capable mobile app.
My solution is based on https://adrianhall.github.io/develop-mobile-apps-with-csharp-and-azure/chapter3/client/
Here is the code that I use for offline sync :
public class AzureDataSource
{
private async Task InitializeAsync()
{
// Short circuit - local database is already initialized
if (client.SyncContext.IsInitialized)
{
return;
}
// Define the database schema
store.DefineTable<ArrayElement>();
store.DefineTable<InputAnswer>();
//Same thing with 16 others table
...
// Actually create the store and update the schema
await client.SyncContext.InitializeAsync(store, new MobileServiceSyncHandler());
}
public async Task SyncOfflineCacheAsync()
{
await InitializeAsync();
//Check if authenticated
if (client.CurrentUser != null)
{
// Push the Operations Queue to the mobile backend
await client.SyncContext.PushAsync();
// Pull each sync table
var arrayTable = await GetTableAsync<ArrayElement>();
await arrayTable.PullAsync();
var inputAnswerInstanceTable = await GetTableAsync<InputAnswer>();
await inputAnswerInstanceTable.PullAsync();
//Same thing with 16 others table
...
}
}
public async Task<IGenericTable<T>> GetTableAsync<T>() where T : TableData
{
await InitializeAsync();
return new AzureCloudTable<T>(client);
}
}
public class AzureCloudTable<T>
{
public AzureCloudTable(MobileServiceClient client)
{
this.client = client;
this.table = client.GetSyncTable<T>();
}
public async Task PullAsync()
{
//Query name used for incremental pull
string queryName = $"incsync_{typeof(T).Name}";
await table.PullAsync(queryName, table.CreateQuery());
}
}
The problem is that the syncing takes a lot of time even when there isn't anything to pull (8-9 seconds on Android devices and more than 25 seconds to pull the whole database).
I looked at Fiddler to find how much time takes the Mobile Apps BackEnd to respond and it is about 50 milliseconds per request so the problem doesn't seem to come from here.
Does anyone have the same trouble ? Is there something that I'm doing wrong or tips to improve my sync performance ?
Our particular issue was linked to our database migration. Every row in the database had the same updatedAt value. We ran an SQL script to modify these so that they were all unique.
This fix was actually for some other issue we had, where not all rows were being returned for some unknown reason, but we also saw a substantial speed improvement.
Also, another weird fix that improved loading times was the following.
After we had pulled all of the data the first time (which, understandably takes some time) - we did an UpdateAsync() on one of the rows that were returned, and we did not push it afterwards.
We've come to understand that the way offline sync works, is that it will pull anything that has a date newer than the most recent updated at. There was a small speed improvement associated with this.
Finally, the last thing we did to improve speed was to not fetch the data again, if it already had cached a copy in the view. This may not work for your use case though.
public List<Foo> fooList = new List<Foo>
public void DisplayAllFoo()
{
if(fooList.Count == 0)
fooList = await SyncClass.GetAllFoo();
foreach(var foo in fooList)
{
Console.WriteLine(foo.bar);
}
}
Edit 20th March 2019:
With these improvements in place, we are still seeing very slow sync operations, used in the same way as mentioned in the OP, also including the improvements listed in my answer here.
I encourage all to share their solutions or ideas on how this speed can be improved.
One of the reasons for the slow Pull() is when more than (10) rows get the same UpdatedAt value. This happens when you update the rows at once, for example running an SQL command.
One way to overcome this is to modify the default trigger on the tables. To ensure every row gets a unique UpdateAt, we did something like this:
ALTER TRIGGER [dbo].[TR_dbo_Items_InsertUpdateDelete] ON [dbo].[TableName]
AFTER INSERT, UPDATE, DELETE
AS
BEGIN
DECLARE #InsertedAndDeleted TABLE
(
Id NVARCHAR(128)
);
DECLARE #Count INT,
#Id NVARCHAR(128);
INSERT INTO #InsertedAndDeleted
SELECT Id
FROM inserted;
INSERT INTO #InsertedAndDeleted
SELECT Id
FROM deleted
WHERE Id NOT IN
(
SELECT Id
FROM #InsertedAndDeleted
);
--select * from #InsertedAndDeleted;
SELECT #Count = Count(*)
FROM #InsertedAndDeleted;
-- ************************ UpdatedAt ************************
-- while loop
WHILE #Count > 0
BEGIN
-- selecting
SELECT TOP (1) #Id = Id
FROM #InsertedAndDeleted;
-- updating
UPDATE [dbo].[TableName]
SET UpdatedAt = Convert(DATETIMEOFFSET, DateAdd(MILLISECOND, #Count, SysUtcDateTime()))
WHERE Id = #Id;
-- deleting
DELETE FROM #InsertedAndDeleted
WHERE id = #Id;
-- counter
SET #Count = #Count - 1;
END;
END;
When we recieve orders from web it creates a sales id and stores it. But if i recieve order from web at same time in two instances, it creates two sales orders for the same web order. So how can i stop it?
I kept as Index for weborder number Allow Duplicates:No. But still it doesnt work. Any Suggestions?
(Added as a answer bit late, 'cause I'm slow that way :))
Send a unique identifier like a GUID from the web, save it in SalesTable and in insert check if it already exists - or make a unique index for the field, but you might log these attempted duplicates and it's easier to code it yourself in insert or validateWrite.
This is because the user presses submit button several times. You need to track the number of clicks on the button. For this you need to use js.
var submit = 0;
function checkIsRepeat(){
var isValid = Page_ClientValidate();
if(isValid) {
if(++ submit > 1){
alert('Yours message here');
return false;
}
}
return isValid;
}
I am implementing a website with a dynamodb + nodejs backend. I use Vogels.js in server side to query dynamodb and show results on a webpage. Because my query returns a lot of results, I would like to return only N (such as 5) results back to a user initially, and return the next N results when the user asks for more.
Is there a way I can run two vogels queries with the second query starts from the place where the first query left off ? Thanks.
Yes, vogels fully supports pagination on both query and scan operations.
For example:
var Tweet = vogels.define('tweet', {
hashKey : 'UserId',
rangeKey : 'PublishedDateTime',
schema : {
UserId : Joi.string(),
PublishedDateTime : Joi.date().default(Date.now),
content : Joi.string()
}
});
// Fetch the 5 most recent tweets from user with id 555:
Tweet.query(555).limit(5).descending().exec(function (err, data) {
var paginationKey = data.LastEvaluatedKey;
// Fetch the next page of 5 tweets
Tweet.query(555).limit(5).descending().startKey(paginationKey).exec()
});
Yes it is possible, DynamoDB has some thing called "LastEvaluatedKey" which will server your purpose.
Step 1) Query your table with option "Limit" = number of records
refer: http://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Query.html
Step 2) If your query has more records than the "Limit value", DynamoDB will return a "LastEvaluatedKey" which you can pass in your next query as "ExclusiveStartKey" to get next set of records until there are no records left
refer: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/QueryAndScan.html#QueryAndScan.Query
Note: Be aware that to get previous set of records you might have to store all the "LastEvaluatedKeys" and implement this at application level
For instance:
$scope.items = $firebase(new Firebase("https://****.firebaseio.com").startAt(100).limit(100));
Starting at the 100th item in the Firebase and ending at 200? I know I can use a skip filter but that still seems to load the first 100 items, correct me if I'm wrong.
You are on the right track. You attach the startAt().limit() code to the Firebase ref and then pass that into $firebase as you have above.
However, the startAt method does not take a numeric offset, but instead a priority and optionally a record id (key).
So where you have put startAt(100), attempting to start after record 100, you would instead need to use the record ID, or prioritize the records in groups of 100.
For background, here's a simple paginator you can check out and steal ideas from. The heart of the example is in nextPage, where it calls startAt using the previous record id like so:
var lastKey = null; // page 0
this.ref.startAt(null, lastKey)
.limit(this.limit + (lastKey? 1 : 0))
.once('value', /* callback to process data goes here */));
UPDATE
Another useful note here is that the records returned by angularFire contain their unique id as $id, which can be useful for determining the id of the last iterated item.