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add function to set nested values and unit tests for it.
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@dfsp-spirit
dfsp-spirit committed Mar 6, 2017
1 parent ac53d19 commit 525a7d7
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282 changes: 172 additions & 110 deletions object_util.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,120 +6,182 @@ function ObjectUtil() {
}

/**
* Some static util functions for retrieving and checking nested keys in objects. Syntax inspired by Immutable. Does support Arrays.
* Some static util functions for retrieving and checking nested keys in JSON objects. Syntax inspired by Immutable. Does support Arrays.
*/


/**
* Checks whether a nested object key exists in an object. Dives into arrays as well.
* @see http://stackoverflow.com/questions/2631001/javascript-test-for-existence-of-nested-object-key
* @param obj the object in which to check for the nested key
* @param path_components an array of strings defining the path (of key names) to the key in question
* @returns {boolean} whether the key exists. (The value may still be null, undefined, or falsy.)
*/
ObjectUtil.hasIn = function(obj, path_components) {
let handled_path = [];
let path_component;
let last_obj = null;
let index;
for (var i = 0; i < path_components.length; i++) {
path_component = path_components[i];
handled_path.push(path_component);
//console.log("At path '" + handled_path.join(', ') + "':");

// special handling for array indices given as number instead of text
if (typeof(path_component) === "number") {
if (Array.isArray(obj)) {
index = path_component;
if (index >= 0 && index < obj.length) {
last_obj = obj;
obj = obj[index];
continue;
}
else {
return false;
}
}

}

if (typeof(obj) != 'object' || obj == null) {
return false; // must be object or array, and the latter is also of type object in JS
}
if(Array.isArray(obj)) {
//console.log("###### At " + handled_path.join(', ') + ": is array.");
if(ObjectUtil._stringRepresentsPositiveIntegerIncludingZero(path_component)) {
let index = parseInt(path_component);
//console.log("###### At " + handled_path.join(', ') + ": is array. index=" + index);
if(index >= 0 && index < obj.length) {
last_obj = obj;
obj = obj[index];
//console.log("###### At " + handled_path.join(', ') + ": is array. index=" + index + ". obj=%o", obj);
}
else {
return false;
}
} else {
return false;
}

}
else {
// is object
if (!obj.hasOwnProperty(path_component)) {
return false;
}
last_obj = obj;
obj = obj[path_component];
}
}
return true;
}


ObjectUtil._stringRepresentsPositiveIntegerIncludingZero = function(str) {
var n = Math.floor(Number(str));
return String(n) === str && n >= 0;
}

/**
* Checks whether a nested object key exists and is not null or undefined.
* @param obj the object in which to check for the nested key
* @param path_components an array of strings defining the path (of key names) to the key in question
* @returns {boolean} whether the key exists and is neither undefined nor null
*/
ObjectUtil.hasDefinedAndNonNullIn = function(obj, path_components) {
if(ObjectUtil.hasIn(obj, path_components)) {
let value = ObjectUtil.getIn(obj, path_components);
let result = (typeof(value) !== 'undefined' && value != null);
return result;
}
return false;
}

/**
* Retrieves the nested obj from the given one. Note that the path has to exist, Check first with hasIn if in doubt.
* @param obj the object
* @param path_components the path to the nested object as an array of strings
* @param alternate an alternate return value that will be used if the given path does not exist in the object
* @returns {Object} the nested object
*/
ObjectUtil.getIn = function(obj, path_components, alternate) {
if(!ObjectUtil.hasIn(obj, path_components)) {
return alternate;
/**
* Checks whether a nested object key exists in an object. Dives into arrays as well.
* @see http://stackoverflow.com/questions/2631001/javascript-test-for-existence-of-nested-object-key
* @param obj the JSON object in which to check for the nested key
* @param path_components an array of strings defining the path (of key names) to the key in question
* @returns {boolean} whether the key exists. (The value may still be null, undefined, or falsy.)
*/
ObjectUtil.hasIn = function(obj, path_components) {
let handled_path = [];
let path_component;
let last_obj = null;
let index;
for (var i = 0; i < path_components.length; i++) {
path_component = path_components[i];
handled_path.push(path_component);

// special handling for array indices given as number instead of text
if (typeof(path_component) === "number") {
if (Array.isArray(obj)) {
index = path_component;
if (index >= 0 && index < obj.length) {
last_obj = obj;
obj = obj[index];
continue;
}
else {
return false;
}
}

}

if (typeof(obj) != 'object' || obj == null) {
return false; // must be object or array, and the latter is also of type object in JS
}
if(Array.isArray(obj)) {
//console.log("###### At " + handled_path.join(', ') + ": is array.");
if(ObjectUtil._stringRepresentsPositiveIntegerIncludingZero(path_component)) {
let index = parseInt(path_component);
//console.log("###### At " + handled_path.join(', ') + ": is array. index=" + index);
if(index >= 0 && index < obj.length) {
last_obj = obj;
obj = obj[index];
//console.log("###### At " + handled_path.join(', ') + ": is array. index=" + index + ". obj=%o", obj);
}
else {
return false;
}
} else {
return false;
}

}
let path_component;
for (var i = 0; i < path_components.length; i++) {
path_component = path_components[i];
if(Array.isArray(obj)) {
let index = parseInt(path_component);
obj = obj[index];
} else {
obj = obj[path_component];
}
}
return obj;
}
else {
// is object
if (!obj.hasOwnProperty(path_component)) {
return false;
}
last_obj = obj;
obj = obj[path_component];
}
}
return true;
}


ObjectUtil._stringRepresentsPositiveIntegerIncludingZero = function(str) {
var n = Math.floor(Number(str));
return String(n) === str && n >= 0;
}

/**
* Checks whether a nested object key exists and is not null or undefined.
* @param obj the JSON object in which to check for the nested key
* @param path_components an array of strings defining the path (of key names) to the key in question
* @returns {boolean} whether the key exists and is neither undefined nor null
*/
ObjectUtil.hasDefinedAndNonNullIn = function(obj, path_components) {
if(ObjectUtil.hasIn(obj, path_components)) {
let value = ObjectUtil.getIn(obj, path_components);
let result = (typeof(value) !== 'undefined' && value != null);
return result;
}
return false;
}

/**
* Retrieves the nested obj from the given one. Note that the path has to exist, Check first with hasIn if in doubt.
* @param obj the input JSON object
* @param path_components the path to the nested object as an array of strings
* @param alternate an alternate return value that will be used if the given path does not exist in the object
* @returns {Object} the nested object
*/
ObjectUtil.getIn = function(obj, path_components, alternate) {
if(!ObjectUtil.hasIn(obj, path_components)) {
return alternate;
}
let path_component;
for (var i = 0; i < path_components.length; i++) {
path_component = path_components[i];
if(Array.isArray(obj)) {
let index = parseInt(path_component);
obj = obj[index];
} else {
obj = obj[path_component];
}
}
return obj;
}

/**
* Creates a new object based on the old one that has the given path added.
* @param obj the input JSON object
* @param path_components the path to the nested object as an array of strings and/or numbers. You have to use numbers (integers >= 0 to be more precise) if you want to set array values.
* @param value_to_use_for_leaf the value to set for the final path element
* @param value_to_use_for_missing_array_elements a value to push into arrays to fill them to the required length, if needed. Optional, defaults to undefined.
* @returns {Object} the new JSON object, which includes the requested path
**/
ObjectUtil.addPathIn = function(obj, path_components, value_to_use_for_leaf, value_to_use_for_missing_array_elements) {

var obj_cp = Object.assign({}, obj);

if(ObjectUtil.hasIn(obj, path_components)) {
return obj_cp;
}

var path_component_is_number = path_components.map(path_component => (typeof path_component === "number"));


// handle requested array at root
if(path_components.length > 0 && path_component_is_number[0]) {
obj_cp = [];
}


var sub_obj = obj_cp;
var path_component;
var index;
var current_path_component_is_number;
var next_path_component_is_number;
for (var i = 0; i < path_components.length; i++) {
path_component = path_components[i];

if (typeof(sub_obj[path_component]) != 'object' || sub_obj[path_component] == null) { // need to create path
next_path_component_is_number = ((i < path_components.length - 1) && path_component_is_number[i+1]);
current_path_component_is_number = path_component_is_number[i];
if(next_path_component_is_number) {
if(!Array.isArray(sub_obj[path_component])) {
sub_obj[path_component] = [];
}
}
else {
// In case of an array: we may need to add array elements before this one before we can insert it
if(current_path_component_is_number) {
if(Array.isArray(sub_obj)) {
index = path_component;
while(index >= sub_obj.length) {
sub_obj.push(value_to_use_for_missing_array_elements);
}
}
}
sub_obj[path_component] = {};
if(i === (path_components.length - 1)) {
sub_obj[path_component] = value_to_use_for_leaf;
}
}
}

sub_obj = sub_obj[path_component];
}
return obj_cp;
}



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