by_an_entry.md

By An Entry

A document may have many entries such as Name, Age, Height, etc. Sometimes, several documents would have the common entry. We can search for these documents if we know the entry name and value.

collection.find(doc! {"Name": "Bob"}).unwrap();

To search for the documents, we use find with doc! as its parameter. In the example above, we specify an entry with name Name and value Bob in doc!. This will return all the documents that have such an entry. And then we can access the other entries of these documents.

The complete code is presented below:

use polodb_core::{bson::doc, Database};

fn main() {
    let db = Database::open_memory().unwrap();
    let collection = db.collection("name_of_the_collection");

    let docs = [
        doc! {
            "Name": "Alice",
            "Age": 20,
        },
        doc! {
            "Name": "Bob",
            "Height": 180,
        },
    ];
    collection.insert_many(docs).unwrap();

    let docs_found = collection.find(doc! {"Name": "Bob"}).unwrap();
    for doc in docs_found {
        println!("{:#?}", doc.unwrap());
    }
}

Output:

Document({
    "Name": String(
        "Bob",
    ),
    "Height": Int32(
        180,
    ),
    "_id": ObjectId(
        "66b613e6d08028e445046942",
    ),
})

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