You must define the ParentId in the category class as nullable to use it as the foreign key property for an optional relationship: public int? ParentId { get; set; } An int property cannot take the value null and therefore cannot represent a NULL as value in a database column.
It probably makes the most sense to pass it as a property, but if you really need to get it programmatically, and from inside the component, you can wait for the component to mount, find its DOM node, and then look at its parent. Here’s an example: class Application extends React.Component { constructor() { super(); … Read more
When Angular runs change detection and the binding to the ngIf input of the NgIf directive is updated, NgIf removes the component from the DOM. After the component is removed from the DOM ngDestroy() is called and then the component is free to get garbage collected. If the parent component is removed while the *ngIf … Read more
Syntax of waitpid(): pid_t waitpid(pid_t pid, int *status, int options); The value of pid can be: < -1: Wait for any child process whose process group ID is equal to the absolute value of pid. -1: Wait for any child process. 0: Wait for any child process whose process group ID is equal to that … Read more
The dragging will be a bit more tricky because you need to work out where would the x/y positions of the mouse on the screen (screen space) will be in the 3D world, then you will need to cast a ray and check if it intersects the object you want to drag. I presume this … Read more
You can simply get the #xyz div first, then find all div children: var childDivs = document.getElementById(‘xyz’).getElementsByTagName(‘div’) // ^ Get #xyz element; ^ find it’s `div` children. The advantage of this method over Document.querySelectorAll is that these selectors work in pretty much every browser, as opposed to IE 8/9+ for the queryselector.
You can always create a globally accessible function which closes the Bootstrap modal window. eg. window.closeModal = function(){ $(‘#iframeModal’).modal(‘hide’); }; Then from the iframe, call it using: window.parent.closeModal();
This is because you are not telling f2 who its Parent is. If this is an MDI application, then f2 should have its MdiParent set to f1. Form f2 = new Form() { Width = 400, Height = 300 }; f2.StartPosition = FormStartPosition.CenterParent; f2.MdiParent = f1; f2.Show(); If this is not an MDI application, then … Read more
Impossible? Hold my beer. Make the select element aware of the current option. CSS can handle the rest. For this, all we need is a value assignment in the onchange event. With a little more effort you can also initialize the <select> tag by its original value; not included below but it’s super easy, just … Read more
If the spawning process (parent) ends before the spawned process (child) does, then the parent-child chain is broken. To make use of this, you’d have to use an intermediate stub-process like so: Caller.exe → Stub.exe → File.exe. Here Stub.exe is simple launcher program that ends just after starting File.exe.