detalib 0.1.0

A Rust client for Deta Base
Documentation 
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use serde_json::{Map, Value};
use serde::{Serialize, Serializer};

use crate::{base::Base, errors::DetaError};

/// Represents the operation to be performed on a field.
#[derive(Debug, PartialEq)]
pub enum Operation {
    /// Set the field to the given value.
    Set,
    /// Delete the field.
    Delete,
    /// Append the given value to the field.
    Append,
    /// Prepend the given value to the field.
    Prepend,
    /// Increment the field by the given numeric value. Use negative values to decrement.
    Increment,
}

impl Operation {
    pub fn as_string(&self) -> String {
        format!("{:?}", self).to_lowercase()
    }
}

/// Represents an updater to update a field in a record.
/// 
/// For delete operations, the value is ignored so it can be anything.
/// For all other operations, the value is used.
/// 
/// A single updater can contain multiple updates.
/// 
/// An Updater can not contain delete operation along with any other operation for the same field.
pub struct Updater {
    key: String,
    base: Base,
    map: Vec<(String, Value, Operation)>
}

impl Updater {
    pub (crate) fn new(base: Base, key: &str) -> Updater {
        Updater {
            base,
            key: key.to_string(),
            map: Vec::new()
        }
    }
    
    /// Set a field to the given value with the operation to be performed.
    pub fn operation(mut self, op: Operation, field: &str, value: Value) -> Self {
        self.map.push((field.to_string(), value, op));
        self
    }

    /// Update a record by key in the base.
    pub fn run(&self) -> Result<Value, DetaError> {
        self.base.request("PATCH", &format!("/items/{}", self.key), Some(serde_json::to_value(self).unwrap()))
    }

}

impl Serialize for Updater {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
        where S: Serializer
    {
        let mut map = Map::new();

        for &(ref field, ref value, ref operation) in &self.map {
            let operation_vec = map.entry(operation.as_string())
                    .or_insert(Value::Array(Vec::new())).as_array_mut().unwrap();
            if operation == &Operation::Delete {
                operation_vec.push(Value::String(field.clone()));
            } else {
                let mut inner_map = Map::new();
                inner_map.insert(field.clone(), value.clone());
                operation_vec.push(Value::Object(inner_map));
            }
        }
        Value::Object(map).serialize(serializer)
    }
}