Trait AnyJsonExpressionMethods 

pub trait AnyJsonExpressionMethods: Expression + Sized {
    // Provided method
    fn retrieve_as_text<T>(self, other: T) -> RetrieveAsText<Self, T>
       where T: JsonIndex,
             <T::Expression as Expression>::SqlType: SqlType { ... }
}

Available on (crate features sqlite or postgres_backend) and (crate features postgres_backend or sqlite) only.

PostgreSQL specific methods present on JSON and JSONB expressions.

Provided Methods

fn retrieve_as_text<T>(self, other: T) -> RetrieveAsText<Self, T>

where T: JsonIndex, <T::Expression as Expression>::SqlType: SqlType,

Creates a ->> expression JSON.

This operator extracts the value associated with the given key, that is provided on the Right Hand Side of the operator.

Extracts n’th element of JSON array (array elements are indexed from zero, but negative integers count from the end). Extracts JSON object field as Text with the given key.

Example

let santas_address: serde_json::Value = serde_json::json!({
    "street": "Article Circle Expressway 1",
    "city": "North Pole",
    "postcode": "99705",
    "state": "Alaska"
});
diesel::insert_into(contacts)
    .values((name.eq("Claus"), address.eq(&santas_address)))
    .execute(conn)?;

let santas_postcode = contacts.select(address.retrieve_as_text("postcode")).get_result::<String>(conn)?;
assert_eq!(santas_postcode, "99705");


let robert_downey_jr_addresses: serde_json::Value = serde_json::json!([
    {
        "street": "Somewhere In La 251",
        "city": "Los Angeles",
        "postcode": "12231223",
        "state": "California"
    },
    {
        "street": "Somewhere In Ny 251",
        "city": "New York",
        "postcode": "3213212",
        "state": "New York"
    }
]);

diesel::insert_into(contacts)
    .values((name.eq("Robert Downey Jr."), address.eq(&robert_downey_jr_addresses)))
    .execute(conn)?;

let roberts_second_address_in_db = contacts
                            .filter(name.eq("Robert Downey Jr."))
                            .select(address.retrieve_as_text(1))
                            .get_result::<String>(conn)?;

let roberts_second_address = serde_json::json!{{
    "city": "New York",
    "state": "New York",
    "street": "Somewhere In Ny 251",
    "postcode": "3213212"
    }};
assert_eq!(roberts_second_address, serde_json::from_str::<serde_json::Value>(&roberts_second_address_in_db).unwrap());

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<T> AnyJsonExpressionMethods for T

where T: Expression, T::SqlType: JsonOrNullableJsonOrJsonbOrNullableJsonb,