rulemorph 0.3.1

YAML-based declarative data transformation engine for CSV/JSON to JSON
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

use super::*;

pub(in crate::transform) fn cast_value(
    value: &JsonValue,
    type_name: &str,
    path: &str,
) -> Result<JsonValue, TransformError> {
    match type_name {
        "string" => Ok(JsonValue::String(value_to_string(value, path)?)),
        "int" => cast_to_int(value, path),
        "float" => cast_to_float(value, path),
        "bool" => cast_to_bool(value, path),
        _ => Err(TransformError::new(
            TransformErrorKind::TypeCastFailed,
            "type must be string|int|float|bool",
        )
        .with_path(path)),
    }
}

fn cast_to_int(value: &JsonValue, path: &str) -> Result<JsonValue, TransformError> {
    match value {
        JsonValue::Number(n) => {
            if let Some(i) = n.as_i64() {
                Ok(JsonValue::Number(i.into()))
            } else if let Some(f) = n.as_f64() {
                if (f.fract()).abs() < f64::EPSILON {
                    Ok(JsonValue::Number((f as i64).into()))
                } else {
                    Err(type_cast_error("int", path))
                }
            } else {
                Err(type_cast_error("int", path))
            }
        }
        JsonValue::String(s) => s
            .parse::<i64>()
            .map(|i| JsonValue::Number(i.into()))
            .map_err(|_| type_cast_error("int", path)),
        _ => Err(type_cast_error("int", path)),
    }
}

fn cast_to_float(value: &JsonValue, path: &str) -> Result<JsonValue, TransformError> {
    match value {
        JsonValue::Number(n) => n
            .as_f64()
            .ok_or_else(|| type_cast_error("float", path))
            .and_then(|f| {
                serde_json::Number::from_f64(f)
                    .map(JsonValue::Number)
                    .ok_or_else(|| type_cast_error("float", path))
            }),
        JsonValue::String(s) => s
            .parse::<f64>()
            .map_err(|_| type_cast_error("float", path))
            .and_then(|f| {
                serde_json::Number::from_f64(f)
                    .map(JsonValue::Number)
                    .ok_or_else(|| type_cast_error("float", path))
            }),
        _ => Err(type_cast_error("float", path)),
    }
}

fn cast_to_bool(value: &JsonValue, path: &str) -> Result<JsonValue, TransformError> {
    match value {
        JsonValue::Bool(b) => Ok(JsonValue::Bool(*b)),
        JsonValue::String(s) => match s.to_lowercase().as_str() {
            "true" => Ok(JsonValue::Bool(true)),
            "false" => Ok(JsonValue::Bool(false)),
            _ => Err(type_cast_error("bool", path)),
        },
        _ => Err(type_cast_error("bool", path)),
    }
}

fn type_cast_error(type_name: &str, path: &str) -> TransformError {
    TransformError::new(
        TransformErrorKind::TypeCastFailed,
        format!("failed to cast to {}", type_name),
    )
    .with_path(path)
}