dataloader 0.18.0

Rust implementation of Facebook's DataLoader using async-await.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150

use dataloader::cached::Loader;
use dataloader::BatchFn;
use fake::faker::company::en::CompanyName;
use fake::faker::name::en::Name;
use fake::{Dummy, Fake, Faker};
use futures::executor::block_on;
use juniper::{self, EmptyMutation, EmptySubscription, FieldResult, Variables};
use std::collections::HashMap;
use std::future::ready;

pub struct CultBatcher;

impl BatchFn<i32, Cult> for CultBatcher {
    async fn load(&mut self, keys: &[i32]) -> HashMap<i32, Cult> {
        println!("load cult by batch {:?}", keys);
        let ret = keys
            .iter()
            .map(|k| {
                let mut cult: Cult = Faker.fake();
                cult.id = k.clone();
                (k.clone(), cult)
            })
            .collect();
        ready(ret).await
    }
}

#[derive(Clone)]
pub struct AppContext {
    cult_loader: Loader<i32, Cult, CultBatcher>,
}

impl AppContext {
    pub fn new() -> AppContext {
        AppContext {
            cult_loader: Loader::new(CultBatcher),
        }
    }
}

impl juniper::Context for AppContext {}

struct Query;

#[juniper::graphql_object(Context = AppContext)]
impl Query {
    async fn persons(_context: &AppContext) -> FieldResult<Vec<Person>> {
        let persons = fake::vec![Person; 10..20];
        Ok(persons)
    }

    async fn cult(&self, id: i32, ctx: &AppContext) -> Cult {
        ctx.cult_loader.load(id).await
    }
}

type Schema =
    juniper::RootNode<'static, Query, EmptyMutation<AppContext>, EmptySubscription<AppContext>>;

#[derive(Debug, Clone, Dummy)]
pub struct Person {
    #[dummy(faker = "1..999")]
    pub id: i32,
    #[dummy(faker = "Name()")]
    pub name: String,
    #[dummy(faker = "1..999")]
    pub cult: i32,
}

#[juniper::graphql_object(Context = AppContext)]
impl Person {
    pub fn id(&self) -> i32 {
        self.id
    }

    pub fn name(&self) -> &str {
        self.name.as_str()
    }

    pub async fn cult(&self, ctx: &AppContext) -> FieldResult<Option<Cult>> {
        let fut = ctx.cult_loader.load(self.cult);
        Ok(Some(fut.await))
    }

    pub async fn cult_by_id(&self, id: i32, ctx: &AppContext) -> Cult {
        ctx.cult_loader.load(id).await
    }
}

#[derive(Debug, Clone, Dummy)]
pub struct Cult {
    #[dummy(faker = "1..999")]
    pub id: i32,
    #[dummy(faker = "CompanyName()")]
    pub name: String,
}

#[juniper::graphql_object(Context = AppContext)]
impl Cult {
    pub fn id(&self) -> i32 {
        self.id
    }

    pub fn name(&self) -> &str {
        self.name.as_str()
    }
}

fn main() {
    let ctx = AppContext::new();
    let schema = Schema::new(Query, EmptyMutation::new(), EmptySubscription::new());
    let vars = Variables::new();
    let q = r#"
        query {
            c1: cult(id: 1) {
              id
              name
            }
            c2: cult(id: 2) {
              id
              name
            }
            c3: cult(id: 3) {
              id
              name
            }
            persons {
              id
              name
              cult {
                id
                name
              }
              c1: cultById(id: 4) {
                id
                name
              }
              c2: cultById(id: 5) {
                id
                name
              }
              c3: cultById(id: 6) {
                id
                name
              }
            }
        }"#;
    let f = juniper::execute(q, None, &schema, &vars, &ctx);
    let (_res, _errors) = block_on(f).unwrap();
}