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
151
152
153
154

use super::StringCodec;

/// A codec for storing JSON messages that relies on [`serde_json`] to parse.
///
/// ## Example
/// ```
/// # use leptos::*;
/// # use leptos_use::storage::{StorageType, use_local_storage, use_session_storage, use_storage, UseStorageOptions};
/// # use serde::{Deserialize, Serialize};
/// # use leptos_use::utils::JsonCodec;
/// #
/// # pub fn Demo() -> impl IntoView {
/// // Primitive types:
/// let (get, set, remove) = use_local_storage::<i32, JsonCodec>("my-key");
///
/// // Structs:
/// #[derive(Serialize, Deserialize, Clone, Default, PartialEq)]
/// pub struct MyState {
///     pub hello: String,
/// }
/// let (get, set, remove) = use_local_storage::<MyState, JsonCodec>("my-struct-key");
/// #    view! { }
/// # }
/// ```
///
/// ## Versioning
///
/// If the JSON decoder fails, the storage hook will return `T::Default` dropping the stored JSON value. See [`Codec`](super::Codec) for general information on codec versioning.
///
/// ### Rely on serde
/// This codec uses [`serde_json`] under the hood. A simple way to avoid complex versioning is to rely on serde's [field attributes](https://serde.rs/field-attrs.html) such as [`serde(default)`](https://serde.rs/field-attrs.html#default) and [`serde(rename = "...")`](https://serde.rs/field-attrs.html#rename).
///
/// ### String replacement
/// Previous versions of leptos-use offered a `merge_defaults` fn to rewrite the encoded value. This is possible by wrapping the codec but should be avoided.
///
/// ```
/// # use leptos::*;
/// # use leptos_use::storage::{StorageType, use_local_storage, use_session_storage, use_storage, UseStorageOptions};
/// # use serde::{Deserialize, Serialize};
/// # use leptos_use::utils::StringCodec;
/// #
/// # pub fn Demo() -> impl IntoView {
/// #[derive(Serialize, Deserialize, Clone, Default, PartialEq)]
/// pub struct MyState {
///     pub hello: String,
///     pub greeting: String,
/// }
///
/// #[derive(Clone, Default)]
/// pub struct MyStateCodec();
/// impl StringCodec<MyState> for MyStateCodec {
///     type Error = serde_json::Error;
///
///     fn encode(&self, val: &MyState) -> Result<String, Self::Error> {
///         serde_json::to_string(val)
///     }
///
///     fn decode(&self, stored_value: String) -> Result<MyState, Self::Error> {
///         let default_value = MyState::default();
///         let rewritten = if stored_value.contains(r#""greeting":"#) {
///             stored_value
///         } else {
///             // add "greeting": "Hello" to the string
///             stored_value.replace("}", &format!(r#""greeting": "{}"}}"#, default_value.greeting))
///         };
///         serde_json::from_str(&rewritten)
///     }
/// }
///
/// let (get, set, remove) = use_local_storage::<MyState, MyStateCodec>("my-struct-key");
/// #    view! { }
/// # }
/// ```
///
/// ### Transform a `JsValue`
/// A better alternative to string replacement might be to parse the JSON then transform the resulting `JsValue` before decoding it to to your struct again.
///
/// ```
/// # use leptos::*;
/// # use leptos_use::storage::{StorageType, use_local_storage, use_session_storage, use_storage, UseStorageOptions};
/// # use serde::{Deserialize, Serialize};
/// # use serde_json::json;
/// # use leptos_use::utils::StringCodec;
/// #
/// # pub fn Demo() -> impl IntoView {
/// #[derive(Serialize, Deserialize, Clone, Default, PartialEq)]
/// pub struct MyState {
///     pub hello: String,
///     pub greeting: String,
/// }
///
/// #[derive(Clone, Default)]
/// pub struct MyStateCodec();
/// impl StringCodec<MyState> for MyStateCodec {
///     type Error = serde_json::Error;
///
///     fn encode(&self, val: &MyState) -> Result<String, Self::Error> {
///         serde_json::to_string(val)
///     }
///
///     fn decode(&self, stored_value: String) -> Result<MyState, Self::Error> {
///         let mut val: serde_json::Value = serde_json::from_str(&stored_value)?;
///         // add "greeting": "Hello" to the object if it's missing
///         if let Some(obj) = val.as_object_mut() {
///             if !obj.contains_key("greeting") {
///                obj.insert("greeting".to_string(), json!("Hello"));
///             }
///             serde_json::from_value(val)
///         } else {
///             Ok(MyState::default())
///         }
///     }
/// }
///
/// let (get, set, remove) = use_local_storage::<MyState, MyStateCodec>("my-struct-key");
/// #    view! { }
/// # }
/// ```
#[derive(Copy, Clone, Default, PartialEq)]
pub struct JsonCodec;

impl<T: serde::Serialize + serde::de::DeserializeOwned> StringCodec<T> for JsonCodec {
    type Error = serde_json::Error;

    fn encode(&self, val: &T) -> Result<String, Self::Error> {
        serde_json::to_string(val)
    }

    fn decode(&self, str: String) -> Result<T, Self::Error> {
        serde_json::from_str(&str)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_json_codec() {
        #[derive(Clone, Debug, PartialEq, serde::Serialize, serde::Deserialize)]
        struct Test {
            s: String,
            i: i32,
        }
        let t = Test {
            s: String::from("party time 🎉"),
            i: 42,
        };
        let codec = JsonCodec;
        let enc = codec.encode(&t).unwrap();
        let dec: Test = codec.decode(enc).unwrap();
        assert_eq!(dec, t);
    }
}