Function serde_json::de::from_str

source · 
pub fn from_str<'a, T>(s: &'a str) -> Result<T>where
    T: Deserialize<'a>,
Expand description

Deserialize an instance of type T from a string of JSON text.

Example

use serde::Deserialize;

#[derive(Deserialize, Debug)]
struct User {
    fingerprint: String,
    location: String,
}

fn main() {
    // The type of `j` is `&str`
    let j = "
        {
            \"fingerprint\": \"0xF9BA143B95FF6D82\",
            \"location\": \"Menlo Park, CA\"
        }";

    let u: User = serde_json::from_str(j).unwrap();
    println!("{:#?}", u);
}

Errors

This conversion can fail if the structure of the input does not match the structure expected by T, for example if T is a struct type but the input contains something other than a JSON map. It can also fail if the structure is correct but T’s implementation of Deserialize decides that something is wrong with the data, for example required struct fields are missing from the JSON map or some number is too big to fit in the expected primitive type.

Examples found in repository?
src/value/ser.rs (line 913)
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    fn serialize_str(self, value: &str) -> Result<Value> {
        crate::from_str(value)
    }
More examples
Hide additional examples
src/raw.rs (line 181)
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    pub fn from_string(json: String) -> Result<Box<Self>, Error> {
        {
            let borrowed = crate::from_str::<&Self>(&json)?;
            if borrowed.json.len() < json.len() {
                return Ok(borrowed.to_owned());
            }
        }
        Ok(Self::from_owned(json.into_boxed_str()))
    }
src/value/de.rs (line 118)
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            fn visit_map<V>(self, mut visitor: V) -> Result<Value, V::Error>
            where
                V: MapAccess<'de>,
            {
                match visitor.next_key_seed(KeyClassifier)? {
                    #[cfg(feature = "arbitrary_precision")]
                    Some(KeyClass::Number) => {
                        let number: NumberFromString = visitor.next_value()?;
                        Ok(Value::Number(number.value))
                    }
                    #[cfg(feature = "raw_value")]
                    Some(KeyClass::RawValue) => {
                        let value = visitor.next_value_seed(crate::raw::BoxedFromString)?;
                        crate::from_str(value.get()).map_err(de::Error::custom)
                    }
                    Some(KeyClass::Map(first_key)) => {
                        let mut values = Map::new();

                        values.insert(first_key, tri!(visitor.next_value()));
                        while let Some((key, value)) = tri!(visitor.next_entry()) {
                            values.insert(key, value);
                        }

                        Ok(Value::Object(values))
                    }
                    None => Ok(Value::Object(Map::new())),
                }
            }
        }

        deserializer.deserialize_any(ValueVisitor)
    }
}

impl FromStr for Value {
    type Err = Error;
    fn from_str(s: &str) -> Result<Value, Error> {
        super::super::de::from_str(s)
    }