ZangoDB

Class: Cursor

Cursor

Class representing a query cursor. Note: The filter, limit, skip, project, group, unwind and sort, methods each add an additional stage to the cursor pipeline and thus do not override any previous invocations.

new Cursor()

cursor.js, line 30
Note: Do not instantiate directly.

Methods

filter(expr){Cursor}

cursor.js, line 160
Filter documents.
Name Type Description
expr object The query document to filter by.
Returns:
Type Description
Cursor
Example
col.find().filter({ x: 4 });

forEach(fn, cb){Promise}

cursor.js, line 69
Iterate over each document and apply a function.
Name Type Description
fn function optional The function to apply to each document.
cb function optional The result callback.
Returns:
Type Description
Promise
Example
col.find().forEach((doc) => {
    console.log('doc:', doc);
}, (error) => {
    if (error) { throw error; }
});

group(spec){Cursor}

cursor.js, line 204
Group documents by an _id and optionally add computed fields.
Name Type Description
spec object Specification for grouping documents.
Returns:
Type Description
Cursor
Example
col.find().group({
    _id: '$author',
    books: { $push: '$book' },
    count: { $sum: 1 }
});

hint(path){Cursor}

cursor.js, line 133
Suggest an index to use. Note: When an index hint is used only documents that contain the indexed path will be in the results.
Name Type Description
path string An indexed path to use.
Returns:
Type Description
Cursor
Example
col.find().hint('myindex');

limit(num){Cursor}

cursor.js, line 170
Limit the number of documents that can be iterated.
Name Type Description
num number The limit.
Returns:
Type Description
Cursor
Example
col.find().limit(10);

project(spec){Cursor}

cursor.js, line 190
Add new fields, and include or exclude pre-existing fields.
Name Type Description
spec object Specification for projection.
Returns:
Type Description
Cursor
Example
col.find().project({ _id: 0, x: 1, n: { $add: ['$k', 4] } });

skip(num){Cursor}

cursor.js, line 180
Skip over a specified number of documents.
Name Type Description
num number The number of documents to skip.
Returns:
Type Description
Cursor
Example
col.find().skip(4);

sort(spec){Cursor}

cursor.js, line 238
Sort documents. Note: An index will not be used for sorting unless the query predicate references one of the fields to sort by or Cursor#hint is used. This is so as not to exclude documents that do not contain the indexed field, in accordance with the functionality of MongoDB.
Name Type Description
spec object Specification for sorting.
Returns:
Type Description
Cursor
Examples
// No indexes will be used for sorting.
col.find().sort({ x: 1 });
// If x is indexed, it will be used for sorting.
col.find({ x: { $gt: 4 } }).sort({ x: 1 });
// If x is indexed, it will be used for sorting.
col.find().sort({ x: 1 }).hint('x');

toArray(cb){Promise}

cursor.js, line 104
Collect all documents as an array.
Name Type Description
cb function optional The result callback.
Returns:
Type Description
Promise
Example
col.find().toArray((error, docs) => {
    if (error) { throw error; }

    for (let doc of docs) {
        console.log('doc:', doc);
    }
});

unwind(path){Cursor}

cursor.js, line 214
Deconstruct an iterable and output a document for each element.
Name Type Description
path string A path to an iterable to unwind.
Returns:
Type Description
Cursor
Example
col.find().unwind('$elements');

Events

data

cursor.js, line 13
Cursor data event.
Type:
  • object

end

cursor.js, line 19
Cursor end event.