added a readme

Cargo.toml

@@ -3,8 +3,14 @@ name = "json_dotpath"
 version = "0.1.0"
 authors = ["Ondřej Hruška <ondra@ondrovo.com>"]
 edition = "2018"
-
+license = "MIT"
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+description = "Dotted path access to nested JSON objects (serde_json::Value)"
+repository = "https://git.ondrovo.com/packages/json_dotpath"
+readme = "README.md"
+keywords = ["serde", "json", "dot"]
+categories = [
+    "data-structures"
+]
 
 [dependencies]
 serde = "1"

README.md

@@ -0,0 +1,63 @@
+# json_dotpath
+
+Access members of nested JSON arrays and objects using "dotted paths".
+
+The `DotPaths` trait is implemented for `serde_json::Value`, 
+`serde_json::Map<String, serde_json::Value>`, and  `Vec<serde_json::Value>`.
+
+Any serializable type or `serde_json::Value` can be stored to or retrieved from
+the nested object. Any value stored in the object can also be modified in place 
+by getting a mutable reference.
+
+This crate is useful for tasks such as working with dynamic JSON API payloads,
+parsing config files, or polymorphic data store.
+
+## Supported Operations
+
+### Object and Array
+- Set (dropping the original value, if any)
+- Remove (remove and drop a value)
+- Take (remove a value and deserialize it)
+- Replace (take and set)
+- Get (find & deserialize)
+- Get a mutable reference to a Value
+
+### Array
+Array is an ordered sequence backed by a Vec. It has these additional operations:
+
+- Prepend
+- Append
+- Insert, shifting the following elements
+- Get the last element
+
+### Null
+JSON null can become an array or object by setting it's members (even nested), as if it was an array or object.
+It becomes an array or object of the appropriate type based on the root key.
+
+## Dotted Path Syntax
+
+Array keys must be numeric (integer), or one of the special patterns listed below.
+
+To avoid ambiguity, it's not allowed to use numeric keys (or keys starting with a number) 
+as map keys. Map keys must start with an ASCII letter or underscore and must not contain a dot (`.`).
+
+### Array Index Patterns
+
+- `-` ... prepend
+- `<` ... prepend (or get first)
+- `+` ... append
+- `>` ... append (or get last)
+- `<n`, e.g. `<5` ... insert before the n-th element
+- `>n`, e.g. `>5` ... insert after the n-th element
+
+### Path Examples
+
+- Empty path ... access the root element
+- `5` ... get the element `"five"` from `[0,1,2,3,4,"five"]`
+- `a.b.c` ... get `1` from `{ "a": { "b": { "c": 1 } } }`
+- `a.0.x` ... get `1` from `{ "a": [ { "x": 1 } ] }`
+
+It's possible to create nested arrays or objects by setting a non-existent path,
+provided the key syntax rules are maintained. 
+
+See unit tests for more examples.

src/lib.rs

@@ -4,6 +4,8 @@ use serde_json::{Map, Value};
 use std::cmp::Ordering;
 use std::mem;
 
+#[macro_use] extern crate serde_derive;
+
 /// Access and mutate nested JSON elements by dotted paths
 ///
 /// The path is composed of keys separated by dots, e.g. `foo.bar.1`.
@@ -540,6 +542,7 @@ mod tests {
     use crate::DotPaths;
     use serde_json::json;
     use serde_json::Value;
+    use serde::{Serialize,Deserialize};
 
     #[test]
     fn get_scalar_with_empty_path() {
@@ -804,4 +807,49 @@ mod tests {
         );
         assert_eq!(json!({"one": "two", "x": {"bbb": ["betelgeuze"]}}), vec);
     }
+
+    #[test]
+    fn stamps() {
+        let mut stamps = Value::Null;
+        // null will become Value::Array(vec![])
+
+        #[derive(Serialize,Deserialize,PartialEq,Default)]
+        struct Stamp {
+            country: String,
+            year: u32,
+            color: String,
+            #[serde(rename = "face value")]
+            face_value: String,
+        };
+
+        stamps.dot_set("0", json!({
+            "country": "British Mauritius",
+            "year": 1847,
+            "color": "orange",
+            "face value": "1 penny"
+        }));
+
+        // append
+        stamps.dot_set(">", Stamp {
+            country: "British Mauritius".to_string(),
+            year: 1847,
+            color: "blue".to_string(),
+            face_value: "2 pence".to_string(),
+        });
+
+        assert_eq!("orange", stamps.dot_get::<String>("0.color").unwrap());
+        assert_eq!("blue", stamps.dot_get::<String>("1.color").unwrap());
+
+        assert_eq!(1847, stamps.dot_get::<Stamp>("1").unwrap().year);
+
+        // Remove the first stamp's "face value" attribute
+        assert_eq!(Some("1 penny".to_string()), stamps.dot_get("0.face value"));
+        stamps.dot_remove("0.face value");
+        assert_eq!(Option::<Value>::None, stamps.dot_get("0.face value"));
+
+        // change the second stamp's year
+        let old_year : u32 = stamps.dot_replace("1.year", 1850).unwrap();
+        assert_eq!(1847, old_year);
+        assert_eq!(1850, stamps.dot_get::<u32>("1.year").unwrap());
+    }
 }