Cursor
Cursors are returned by calls to Collection.find() and are used to iterate the results of a query.
Cursors can also apply projections to return only selected fields and can run Squirrel scripts to process query results.
hasNext
hasNext checks if the cursor has any more documents remaining.
Parameters
None
Returns
True if there are documents remaining, false if not
next
next gets the next document as a JSON string
Parameters
None
Returns
The next query result as a JSON string
Example
NodeJS
while(cursor.hasNext()) {
var doc = cursor.next();
// do something with the document
}
count
Returns the number of documents that the cursor will retrieve. Note that this will iterate the cursor and can be a (relatively) slow function to call.
Parameters
None
Returns
The number of documents that the cursor will retrieve.
setLimit
Limits the number of documents that the cursor can retrieve.
Parameters
- A maximum number of documents to retrieve before hasNext begins to return false.
Returns
A self-reference to the cursor.
setProjection
A projection can be used to select which fields are to be retrived rather than the whole document. SpinoDB uses whitelist projections only.
The projection is in the form of a JSON object where the keys of the JSON object are the fields that should be returned, and the values must be 1. E.g.
{
"name": 1,
"age": 1,
"profile": {
"picture": 1
}
}
Parameters
A projection JSON document.
Returns
A self-reference to the cursor.
Example
setLimit and setProjection return self references and can be chained together.
NodeJS
cursor.setLimit(10).setProjection("{\"name\": 1}");
runScript
Cursors can run Squirrel scripts to order, aggregate, format or otherwise process query results.
Refer to the scripting section for more details.
Parameters
- A squirrel script as a string
Returns
The result of the script as a string