For a full overview of MongoDB and all my posts on it, check out my overiew.
If you want to find out all the different values for a field across all the documents in a collection, you can use the ready-made distinct aggregation method to find that out.
With the given data in a collection called podcasts:
{
{
"name": "Tech Over Tea",
"episodeName": "#75 Welcome Our Hacker Neko Waifu | Cyan Nyan",
"dateAired": ISODate("2021-08-02"),
"listenedTo": true,
},
{
"name": "Tech Over Tea",
"episodeName": "Neckbeards Anonymous - Tech Over Tea #20 - feat Donald Feury",
"dateAired": ISODate("2020-07-13"),
"listenedTo": true
},
{
"name": "Tech Over Tea",
"episodeName": "#34 The Return Of The Clones - feat Bryan Jenks",
"dateAired": ISODate("2020-10-19"),
"listenedTo": false
}
}
If you run the following command:
db.podcasts.distinct("episodeName")
The result will be:
[
"#75 Welcome Our Hacker Neko Waifu | Cyan Nyan",
"Neckbeards Anonymous - Tech Over Tea #20 - feat Donald Feury",
"#34 The Return Of The Clones - feat Bryan Jenks"
]
Notice that the result is all the different values for the field episodeName.
You can also do the same on a query result:
db.podcasts.distinct("dateAired", {listenedTo: true})
Will return:
[ISODate("2021-08-02"),ISODate("2020-07-13")]
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