Tutorial by Examples: t

Callbacks are often used to provide error handling. This is a form of control flow branching, where some instructions are executed only when an error occurs: const expected = true; function compare(actual, success, failure) { if (actual === expected) { success(); } else { failure...

If you want to delete rows (or columns) in a loop, you should always loop starting from the end of range and move back in every step. In case of using the code: Dim i As Long With Workbooks("Book1").Worksheets("Sheet1") For i = 1 To 4 If IsEmpty(.Cells(i, 1)) Then...

#Get the active Worksheet my $Book = $Excel->Activewindow; my $Sheet = $Book->Activesheet; #List of Worksheet names my @list_Sheet = map { $_->{'Name'} } (in $Book->{Worksheets}); #Access a given Worksheet my $Sheet = $Book->Worksheets($list_Sheet[0]); #Add new Worksheet...

#Edit the value of a cell (2 methods) $Sheet->Range("A1")->{Value} = 1234; $Sheet->Cells(1,1)->{Value} = 1234; #Edit the values in a range of cells $Sheet->Range("A8:C9")->{Value} = [[ undef, 'Xyzzy', 'Plugh' ], [ 42, 'Pe...

#Insert a row before/after line 22 $Sheet->Rows("22:22")->Insert(xlUp, xlFormatFromRightOrBelow); $Sheet->Rows("23:23")->Insert(-4121,0); #xlDown is -4121 and that xlFormatFromLeftOrAbove is 0 #Delete a row $Sheet->Rows("22:22")->Delete(); ...

In ui-router a state can hold multiple views, each with his own controller and a template .state('dashboard', { name: 'dashboard', url: '/dashboard', views: { "view1": { templateUrl: "path/to/view1.html", controller: "...

You can resolve data into your state when you transition into it, usually it's useful when the state needs to use that data, or to resolve into a state when some provided input needs to be authenticated. When you define your states, you will need to provide a map of values to be resolved into the ....

The syntax for filtering for NULL (i.e. the absence of a value) in WHERE blocks is slightly different than filtering for specific values. SELECT * FROM Employees WHERE ManagerId IS NULL ; SELECT * FROM Employees WHERE ManagerId IS NOT NULL ; Note that because NULL is not equal to anything, not ...

When creating tables it is possible to declare a column as nullable or non-nullable. CREATE TABLE MyTable ( MyCol1 INT NOT NULL, -- non-nullable MyCol2 INT NULL -- nullable ) ; By default every column (except those in primary key constraint) is nullable unless we explicitly set ...

Setting a field to NULL works exactly like with any other value: UPDATE Employees SET ManagerId = NULL WHERE Id = 4

For example inserting an employee with no phone number and no manager into the Employees example table: INSERT INTO Employees (Id, FName, LName, PhoneNumber, ManagerId, DepartmentId, Salary, HireDate) VALUES (5, 'Jane', 'Doe', NULL, NULL, 2, 800, '2016-07-22') ;

To customize appearance of all instances of a class, access appearance proxy of the desired class. For example: Set UIButton tint color Swift: UIButton.appearance().tintColor = UIColor.greenColor() Objective-C: [UIButton appearance].tintColor = [UIColor greenColor]; Set UIButton background...

Use appearanceWhenContainedInInstancesOfClasses: to customize the appearance for instance of a class when contained within an instance of container class. For example customization of UILabel's textColor and backgroundColor within ViewController class will look like this: Set UILabel text color Sw...

Not everyone agrees on what the most semantically correct method for resource creation is. Thus, your API could accept POST or PUT requests, or either. The server should respond with 201 Created if the resource was successfully created. Pick the most appropriate error code if it was not. For examp...

Editing or updating a resource is a common purpose for APIs. Edits can be achieved by sending either POST, PUT or PATCH requests to the respective resource. Although POST is allowed to append data to a resource's existing representation it is recommended to use either PUT or PATCH as they convey a m...

Another common use of HTTP APIs is to delete an existing resource. This should usually be done using DELETE requests. If the deletion was successful, the server should return 200 OK; an appropriate error code if it was not. If our employee Charlie Smith has left the company and we now want to dele...

The last common use of HTTP APIs is to obtain a list of existing resources on the server. Lists like this should be obtained using GET requests, since they only retrieve data. The server should return 200 OK if it can supply the list, or an appropriate error code if not. Listing our employees, the...

A cross-origin request must be sent including the Origin header. This indicates from where the request originated. For example, a cross-origin request from http://example.com to http://example.org would look like this: GET /cors HTTP/1.1 Host: example.org Origin: example.com The server will us...

The response to a CORS request must include an Access-Control-Allow-Origin header, which dictates what origins are allowed to use the CORS resource. This header can take one of three values: An origin. Doing this permits requests from that origin only. The character *. This permits requests from...

Allowing user credentials or the user's session to be sent with a CORS request allows the server to persist user data across CORS requests. This is useful if the server needs to check if the user is logged in before providing data (for example, only performing an action if a user is logged in - this...