Grouping Adjacent States In MongoDB With Aggregation Pipeline
MongoDB Aggregation Pipeline groups adjacent states by combining sort, group, project, unwind, and group stages.
The data of a collection (named states) in the MongoDB database is as follows:
[
{order: 1, state: 'one'},
{order: 2, state: 'one'},
{order: 3, state: 'one'},
{order: 4, state: 'two'},
{order: 5, state: 'two'},
{order: 6, state: 'one'},
{order: 7, state: 'two'},
{order: 8, state: 'three'},
{order: 9, state: 'three'}
]
Requirement: Group by adjacent states.
The expected results are as follows:
[
[
{order: 1, state: 'one'},
{order: 2, state: 'one'},
{order: 3, state: 'one'}
],
[
{order: 4, state: 'two'},
{order: 5, state: '...