proteus 0.5.0

Proteus is intended to make dynamic transformation of data using serde serializable, deserialize using JSON and a JSON transformation syntax similar to Javascript JSON syntax. It also supports registering custom Actions to be used in the syntax.
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

pub mod namespace;

use crate::action::Action;
use crate::errors::Error;
use namespace::Namespace;
use serde::{Deserialize, Serialize};
use serde_json::Value;
use std::borrow::Cow;

/// This type represents an [Action](../action/trait.Action.html) which extracts data from the
/// source JSON Value.
#[derive(Debug, Serialize, Deserialize)]
pub struct Getter {
    namespace: Vec<Namespace>,
}

impl Getter {
    pub fn new(namespace: Vec<Namespace>) -> Self {
        Self { namespace }
    }
}

#[typetag::serde]
impl Action for Getter {
    fn apply<'a>(
        &self,
        source: &'a Value,
        _destination: &mut Value,
    ) -> Result<Option<Cow<'a, Value>>, Error> {
        let mut current = source;
        for ns in &self.namespace {
            current = match expand(ns, current)? {
                Some(value) => value,
                None => return Ok(None),
            };
        }
        Ok(Some(Cow::Borrowed(current)))
    }
}

#[inline]
fn expand<'a>(ns: &Namespace, current: &'a Value) -> Result<Option<&'a Value>, Error> {
    match current {
        Value::Object(o) => match ns {
            Namespace::Object { id } => Ok(o.get(id)),
            _ => Ok(None),
        },
        Value::Array(arr) => match ns {
            Namespace::Array { index } => Ok(arr.get(*index)),
            _ => Ok(None),
        },
        _ => Ok(None),
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::{json, Map};

    #[test]
    fn key_value() -> Result<(), Box<dyn std::error::Error>> {
        let ns = Namespace::parse("key")?;
        let input = json!({"key":"value"});
        let mut output = Value::Object(Map::new());
        let getter = Getter::new(ns);
        let res = getter.apply(&input, &mut output)?;
        assert_eq!(res, Some(Cow::Owned(Value::String("value".into()))));
        Ok(())
    }

    #[test]
    fn array_value_in_object() -> Result<(), Box<dyn std::error::Error>> {
        let ns = Namespace::parse("my_array[0]")?;
        let input = json!({
            "existing_key":"my_val1",
            "my_array":["value"]
        });
        let mut output = Value::Object(Map::new());
        let getter = Getter::new(ns);
        let res = getter.apply(&input, &mut output)?;
        assert_eq!(res, Some(Cow::Owned(Value::String("value".into()))));
        Ok(())
    }

    #[test]
    fn array_value_in_array() -> Result<(), Box<dyn std::error::Error>> {
        let ns = Namespace::parse("[0][0]")?;
        let input = json!([["value"]]);
        let mut output = Value::Object(Map::new());
        let getter = Getter::new(ns);
        let res = getter.apply(&input, &mut output)?;
        assert_eq!(res, Some(Cow::Owned(Value::String("value".into()))));
        Ok(())
    }

    #[test]
    fn array_in_array() -> Result<(), Box<dyn std::error::Error>> {
        let ns = Namespace::parse("[0]")?;
        let input = json!([["value"]]);
        let mut output = Value::Object(Map::new());
        let getter = Getter::new(ns);
        let res = getter.apply(&input, &mut output)?;
        assert_eq!(res, Some(Cow::Owned(json!(["value"]))));
        Ok(())
    }

    #[test]
    fn object_value_in_array() -> Result<(), Box<dyn std::error::Error>> {
        let ns = Namespace::parse("[0].key")?;
        let input = json!([{"key":"value"}]);
        let mut output = Value::Object(Map::new());
        let getter = Getter::new(ns);
        let res = getter.apply(&input, &mut output)?;
        assert_eq!(res, Some(Cow::Owned(json!("value"))));
        Ok(())
    }

    #[test]
    fn array_value_in_object_in_array() -> Result<(), Box<dyn std::error::Error>> {
        let ns = Namespace::parse("[0].key[1]")?;
        let input = json!([{"key":[null,"value"]}]);
        let mut output = Value::Object(Map::new());
        let getter = Getter::new(ns);
        let res = getter.apply(&input, &mut output)?;
        assert_eq!(res, Some(Cow::Owned(json!("value"))));
        Ok(())
    }
}