feat: support optional json path as first argument on RadonOpCodes::StringParseJSONMap

Author: guidiaz

Cargo.lock

@@ -19,6 +19,7 @@ if_rust_version = "1.0.0"
 # the http crate is used to perform additional validations before passing arguments to the surf http client
 # the version of http must be kept in sync with the version used by surf
 http = "0.2.1"
+jsonpath = "0.1.1"
 log = "0.4.8"
 minidom = { git = "https://github.com/witnet/xmpp-rs", rev = "bc8a33ff5da95ee4039ad7ee3376c100d9e35c74" }
 num_enum = "0.4.2"

rad/Cargo.toml

@@ -38,6 +38,15 @@ pub enum RadError {
         description
     )]
     JsonParse { description: String },
+    /// The given JSON path is not present in a JSON-stringified object
+    #[fail(display = "Failed to find JSON path `{}` from RadonString", path)]
+    JsonPathNotFound { path: String },
+    /// Failed to parse a JSON path selector from a string value
+    #[fail(
+        display = "Failed to parse a JSON path from a string value: {:?}",
+        description
+    )]
+    JsonPathParse { description: String },
     /// Failed to parse an object from a XML buffer
     #[fail(
         display = "Failed to parse an object from a XML buffer: {:?}",

rad/src/error.rs

@@ -7,9 +7,11 @@ use std::{
 use base64::Engine;
 use serde_cbor::value::{from_value, Value};
 use serde_json::Value as JsonValue;
+use jsonpath::Selector;
 
 use slicestring::Slice;
 use regex::Regex;
+use witnet_data_structures::radon_error::RadonError;
 
 use crate::{
     error::RadError,
@@ -142,18 +144,42 @@ pub fn parse_json(input: &RadonString) -> Result<RadonTypes, RadError> {
         serde_json::from_str(&input.value()).map_err(|err| RadError::JsonParse {
             description: err.to_string(),
         })?;
-
     RadonTypes::try_from(json_value)
 }
 
-pub fn parse_json_map(input: &RadonString) -> Result<RadonMap, RadError> {
-    let item = parse_json(input)?;
-    item.try_into()
-}
+pub fn parse_json_map(input: &RadonString, args: &Option<Vec<Value>>) -> Result<RadonMap, RadError> {
+    let not_found = |json_path: &str| RadError::JsonPathNotFound { 
+        path: String::from(json_path) 
+    };
+
+    let wrong_args = || RadError::WrongArguments { 
+        input_type: RadonString::radon_type_name(),
+        operator: "ParseJsonMap".to_string(),
+        args: args.to_owned().unwrap_or_default(),
+    };
+
+    let json_input: JsonValue = serde_json::from_str(&input.value())
+        .map_err(|err| RadError::JsonParse {
+                description: err.to_string(),
+    })?;
+    
+    match args.to_owned().unwrap_or_default().get(0) {
+        Some(Value::Text(json_path)) => {
+            let selector = Selector::new(json_path.as_str())
+                .map_err(|err| RadError::JsonPathParse {
+                    description: err.to_string(),
+                })?;
+            let item = selector.find(&json_input)
+                .next()
+                .ok_or_else(|| not_found(json_path.as_str()))?;
+            RadonTypes::try_from(item.to_owned())?.try_into()
+        },
+        None => {
+            RadonTypes::try_from(json_input)?.try_into()
+        },
+        _ => Err(wrong_args())
+    }
 
-pub fn parse_json_array(input: &RadonString) -> Result<RadonArray, RadError> {
-    let item = parse_json(input)?;
-    item.try_into()
 }
 
 fn add_children(

rad/src/operators/string.rs

@@ -134,7 +134,7 @@ impl Operable for RadonString {
             (RadonOpCodes::StringParseJSONArray, None) => string_operators::parse_json_array(self)
                 .map(RadonTypes::from)
                 .map_err(Into::into),
-            (RadonOpCodes::StringParseJSONMap, None) => string_operators::parse_json_map(self)
+            (RadonOpCodes::StringParseJSONMap, args) => string_operators::parse_json_map(self, &args)
                 .map(RadonTypes::from)
                 .map_err(Into::into),
             (RadonOpCodes::StringParseXMLMap, None) => string_operators::parse_xml_map(self)