IDBCursor.md

IDBCursor<TKey, TPrimaryKey, TValue>

Namespace: SpawnDev.SpawnJS.JSObjects
Inherits: SpawnJSObject
Source: JSObjects/IDBCursor.cs
MDN Reference: IDBCursor<TKey, TPrimaryKey, TValue> on MDN

The IDBCursor interface of the IndexedDB API represents a cursor for traversing or iterating over multiple records in a database. The cursor has a source that indicates which index or object store it is iterating over. It has a position within the range, and moves in a direction that is increasing or decreasing in the order of record keys. The cursor enables an application to asynchronously process all the records in the cursor's range. You can have an unlimited number of cursors at the same time. You always get the same IDBCursor object representing a given cursor. Operations are performed on the underlying index or object store. https://developer.mozilla.org/en-US/docs/Web/API/IDBCursor

Constructors

Signature	Description
IDBCursor(SpawnJSObjectReference _ref)	Deserialization constructor

Properties

Property	Type	Access	Description
Source	Union<IDBObjectStore<TPrimaryKey, TValue>, IDBIndex<TKey, TPrimaryKey, TValue>>	get	Returns the IDBObjectStore or IDBIndex that the cursor is iterating. This function never returns null or throws an exception, even if the cursor is currently being iterated, has iterated past its end, or its transaction is not active.
Direction	string	get/set	Returns the direction of traversal of the cursor.
Key	TKey?	get/set	Returns the key for the record at the cursor's position. If the cursor is outside its range, this is set to undefined. The cursor's key can be any data type.
PrimaryKey	TPrimaryKey?	get	Returns the cursor's current effective primary key. If the cursor is currently being iterated or has iterated outside its range, this is set to undefined. The cursor's primary key can be any data type.
Request	IDBRequest<IDBCursor<TKey, TPrimaryKey, TValue>>	get	Returns the IDBRequest that was used to obtain the cursor.

Methods

Method	Return Type	Description
KeyAs()	TKeyAlt	Returns the key for the record at the cursor's position. If the cursor is outside its range, this is set to undefined. The cursor's key can be any data type.
PrimaryKeyAs()	TPrimaryKeyAlt	Returns the cursor's current effective primary key. If the cursor is currently being iterated or has iterated outside its range, this is set to undefined. The cursor's primary key can be any data type.
CanContinue()	Task<bool>	Returns a Task the returns true if (and when) the cursor can continue (Request != null and Request has a result). (non-spec)
Advance(int count)	void	Sets the number of times a cursor should move its position forward. The number of times to move the cursor forward.
AdvanceAsync(int count)	Task<bool>	Sets the number of times a cursor should move its position forward.
Continue(TKey key)	void	Advances the cursor to the next position along its direction, to the item whose key matches the optional key parameter. The key to position the cursor at.
ContinueAsync(TKey key)	Task<bool>	Advances the cursor to the next position along its direction, to the item whose key matches the optional key parameter.
Continue()	void	Advances the cursor to the next position along its direction, to the item whose key matches the optional key parameter.
ContinueAsync()	Task<bool>	Advances the cursor to the next position along its direction, to the item whose key matches the optional key parameter. returns true if there is data
ContinuePrimaryKey(TKey key, TKey primaryKey)	void	Sets the cursor to the given index key and primary key given as arguments. The key to position the cursor at. The primary key to position the cursor at.
ContinuePrimaryKeyAsync(TKey key, TKey primaryKey)	Task<bool>	Sets the cursor to the given index key and primary key given as arguments.
Delete()	IDBRequest	Returns an IDBRequest object, and, in a separate thread, deletes the record at the cursor's position, without changing the cursor's position. This can be used to delete specific records.
DeleteAsync()	Task	Deletes the record at the cursor's position, without changing the cursor's position. This can be used to delete specific records.
Update(TValue value)	IDBRequest<TKey>	Returns an IDBRequest object, and, in a separate thread, updates the value at the current position of the cursor in the object store. This can be used to update specific records. The new value to be stored at the current position. An IDBRequest object on which subsequent events related to this operation are fired.
UpdateAsync(TValue value)	Task<TKey>	Updates the value at the current position of the cursor in the object store. This can be used to update specific records.

Examples

SpawnDev.SpawnJS Mapping Note: The JavaScript examples below show the standard Web API usage. In SpawnDev.SpawnJS, the same API is available with C# conventions:

• Properties and methods use PascalCase (e.g., readyState becomes ReadyState)
• Events use ActionEvent with +=/-= (e.g., addEventListener("click", fn) becomes OnClick += handler)
• Async methods return Task<T> instead of Promise<T>
• Objects should be disposed with using statements
• Access via JS.Get<IDBCursor>(...) or constructor new IDBCursor(...)

function displayData() {
  const transaction = db.transaction(["rushAlbumList"], "readonly");
  const objectStore = transaction.objectStore("rushAlbumList");

  objectStore.openCursor().onsuccess = (event) => {
    const cursor = event.target.result;
    if (cursor) {
      const listItem = document.createElement("li");
      listItem.textContent = `${cursor.value.albumTitle}, ${cursor.value.year}`;
      list.appendChild(listItem);

      cursor.continue();
    } else {
      console.log("Entries all displayed.");
    }
  };
}

See full example on MDN