How do I chain "SelectMany" calls with linqjs (or flatten JSON) - javascript

Using linq.js how can I chain two SelectMany calls together.
Given the following JSON structure:
[
{
"UpFrontCost": "29.95",
"Currency": "USDAUD",
"FittingDate": "2013-07-08 06:30:16Z",
"Widgets": [
{
"ID": 3,
"Name": "Test1"
},
{
"ID": 4,
"Name": "Test19"
},
{
"ID": 6,
"Name": "Test8"
}
]
},
{
"UpFrontCost": "29.95",
"Currency": "USDAUD",
"FittingDate": "2013-07-08 06:30:16Z",
"Widgets": [
{
"ID": 67,
"Name": "Test1"
},
{
"ID": 99,
"Name": "Test19"
},
{
"ID": 34,
"Name": "Test8"
}
]
}
]
I would like a list of all the "Widgets" (in this example a list of 6 widgets).

You don't need to really chain anything. Your root object is an array, you just want to select each widget for each object in that array.
var query = Enumerable.From(jsonObject)
.SelectMany("$.Widgets") // Select each widget found in the Widgets property
.ToArray();
To flatten that array of widgets attaching each property of the parent object to the result, there's a couple of ways you could do it. You can use a nested query using the function syntax.
var query = Enumerable.From(jsonObject)
.SelectMany(function (item) {
return Enumerable.From(item.Widgets)
.Select(function (widget) {
return {
ID: widget.ID,
Name: widget.Name,
UpFrontCost: item.UpFrontCost,
Currency: item.Currency,
FittingDate: item.FittingDate
};
});
})
.ToArray();
Or using the lambda string syntax:
var query = Enumerable.From(items)
.SelectMany("$.Widgets",
// argument 1 ($) - the parent object
// argument 2 ($$) - the selected object (a widget)
"{ ID: $$.ID, Name: $$.Name, UpFrontCost: $.UpFrontCost, Currency: $.Currency, FittingDate: $.FittingDate }"
)
.ToArray();

Related

How do I create an unique dataset of json object literal in Javascript?

I want to get an output as an unique set of Categories array with the following output [Men,Woman].
Is there any way to do it in Javascript?
For example this my data
{
"products:"[
{
"id": 1,
"categories": {
"1": "Men",
},
},
{
"id": 2,
"categories": {
"1": "Men",
},
}, {
"id": 3,
"categories": {
"1": "Woman",
},
}
];
}
A simple 1 line answer would be
new Set(input.products.map(p => p.categories["1"]))
This is if you're expecting only key "1" in the categories object.
If it can have multiple categories then you can always do
const uniqueCategories = new Set();
input.products.forEach(p => uniqueCategories.add(...Object.values(p.categories)))
Now you can convert a Set into an array
PS: This is not a ReactJs problem but a pure JS question. You might want to remove the ReactJs tag from this question altogether.

How to get JSON entry from returned objects

I got JSON data, like:
{
"id": 1,
"active": true,
"dependency": [
{ "id": 2 }
{ "id": 3 }
]
},
{
"id": 2,
"active": true
},
{
"id": 3,
"active": true
}
I want to retrieve the "active" value for each dependency in the id 1 object. So far I used a forEach to get those dependency.
thisElement.dependency.forEach(function(id) {
console.log(id)
}
Which returns id 2 and id 3 as objects. Is there a way to use id.active straight away? By using only one loop? Because the result so far are objects without any connection to the related JSON data. Would it require to loop through the whole JSON data to retrieve those values?
The most efficient thing to to is create a hashmap with an Object or Map first so you only need to iterate the array once to find dependency related values.
You could do it by using Array#find() to search whole array each time but that is far more time complexity than the o(1) object lookup
const activeMap = new Map(data.map(obj => [obj.id, obj.active]))
data[0].dependency.forEach(({id}) => console.log(id ,' active: ' , activeMap.get(id)))
<script>
const data =
[
{
"id": 1,
"active": true,
"dependency": [
{"id": 2 },
{"id": 3}
]
},
{
"id": 2,
"active": false
},
{
"id": 3,
"active": true
}
]
</script>

Dynamically add array elements to JSON Object

I'm creating a JSON object from an array and I want to dynamically push data to this JSON object based on the values from array. See my code for a better understanding of my problem...
for(i=0;i<duplicates.length; i++) {
var request = {
"name": duplicates[i].scope,
"id": 3,
"rules":[
{
"name": duplicates[i].scope + " " + "OP SDR Sync",
"tags": [
{
"tagId": 1,
"variables":[
{
"variable": duplicates[i].variable[j],
"matchType": "Regex",
"value": duplicates[i].scopeDef
}
],
"condition": false,
},
{
"tagId": 1,
"condition": false,
}
],
"ruleSetId": 3,
}
]
}
}
I take object properties from the duplicates array that can have the following elements:
[{scopeDef=.*, scope=Global, variable=[trackingcode, v1, v2]}, {scopeDef=^https?://([^/:\?]*\.)?delta.com/products, scope=Products Section, variable=[v3]}]
As you can see, an object contain variable element that can have multiple values. I need to push to the JSON object all those values dynamically (meaning that there could be more than 3 values in an array).
For example, after I push all the values from the duplicates array, my JSON object should look like this:
name=Products Section,
rules=
[
{
name=Products Section OP SDR Sync,
tags=[
{
variables=
[
{
matchType=Regex,
variable=v3,
value=^https?://([^/:\?]*\.)?delta.com/products
},
{
matchType=Regex,
variable=trackingcode,
value=.*
},
{
matchType=Regex,
variable=v1,
value=.*
},
{
matchType=Regex,
variable=v2,
value=.*
}
],
condition=false,
},
{
condition=false,
tagId=1
}
],
ruleSetId=3
}
]
}
I tried the following code but without success:
for(var j in duplicates[i].variable) {
var append = JSON.parse(request);
append['variables'].push({
"variable":duplicates[i].variable[j],
"matchType": "Regex",
"value": duplicates[i].scopeDef
})
}
Please let me know if I need to provide additional information, I just started working with JSON objects.
First of all, you dont need to parse request, you already create an object, parse only when you get JSON as string, like:
var json='{"a":"1", "b":"2"}';
var x = JSON.parse(json);
Next, you have any property of object wrapped in arrays. To correctly work with it you should write:
request.rules[0].tags[0].variables.push({
"variable":duplicates[i].variable[j],
"matchType": "Regex",
"value": duplicates[i].scopeDef
})
If you want to use your code snippet, you need some changes in request:
var request = {
"name": duplicates[i].scope,
"id": 3,
"variables":[
{
"variable": duplicates[i].variable[j],
"matchType": "Regex",
"value": duplicates[i].scopeDef
}
],
"rules":[
{
"name": duplicates[i].scope + " " + "OP SDR Sync",
"tags": [
{
"tagId": 1,
"condition": false,
},
{
"tagId": 1,
"condition": false,
}
],
"ruleSetId": 3,
}
]
}
}
To understand JSON remember basic rule: read JSON backward. It means:
property
object.property
arrayOfObfects['id'].object.property
mainObject.arrayOfObfects['id'].object.property
and so on. Good luck!

How to filter a JSON tree according to an attribute inside

I have to re-post this questions with more details again:
I got a JSON tree array.
The structure of JSON tree looks like this:
{
"app": {
"categories": {
"cat_222": {
"id": "555",
"deals": [{
"id": "73",
"retailer": "JeansWest"
}, {
"id": "8630",
"retailer": "Adidas"
}, {
"id": "11912",
"retailer": "Adidas"
}]
},
"cat_342": {
"id": "232",
"deals": [{
"id": "5698",
"retailer": "KFC"
}, {
"id": "5701",
"retailer": "KFC"
}, {
"id": "5699",
"retailer": "MC"
}]
}
}
}
}
now, I'd like to filter this JSON tree with var pattern="KF",
return all with retailer name contains KF with it's id.
======================update===========================
Just check my other question. It got solved.
filter multi-dimension JSON arrays
Use Array.filter or _.filter if you need to support IE < 9
Well, you can use _.filter:
var filteredArray = _.filter(arrayOfStrings, function(str) {
return str.indexOf(data) !== -1; });
... or jQuery.grep:
var filteredArray = $.grep(arrayOfStrings, function(str) {
return str.indexOf(data) !== -1; });
As you see, the approaches are quite similar - and, in fact, both use Array.filter, if it's available in the host environment.
Also note that the original array is not affected here. If you want otherwise, just assign the result of filtering to the same variable (i.e., arrayOfStrings in this example).

How to sort an array of objects in ascending order of number?

I have an array of objects like the following :
var array = {
"112" : {
"id": "3",
"name": "raj"
},
"334" : {
"id": "2",
"name": "john"
},
"222" : {
"id": "5",
"name": "kelvin"
}
}
Now i want to sort the array in ascending order of id and then restore it in array. I tried using sort() but could not do it. Please help how to do so that when i display the data from the array it comes sorted.
Assuming you meant your code to be an array of objects, ie:
var unsortedArray = [
{ id: 3, name: "raj" },
{ id: 2, name: "john" },
{ id: 5, name: "kelvin" }
];
Then you would be able to sort by id by passing a function to Array.sort() that compares id's:
var sortedArray = unsortedArray.sort(function(a, b) {
return a.id - b.id
});
As others have pointed out, what you have is an object containing objects, not an array.
var array = {
"112" : {
"id": "3",
"name": "raj"
},
"334" : {
"id": "2",
"name": "john"
},
"222" : {
"id": "5",
"name": "kelvin"
}
}
var sortedObject = Array.prototype.sort.apply(array);
result:
{
"112": {
"id": "3",
"name": "raj"
},
"222": {
"id": "5",
"name": "kelvin"
},
"334": {
"id": "2",
"name": "john"
}
}
That isn't an array, it is an object (or would it if it wasn't for the syntax errors (= should be :)). It doesn't have an order.
You could use an array instead (making the current property names a value of a key on the subobjects).
Alternatively, you could use a for loop to build an array of the key names, then sort that and use it as a basis for accessing the object in order.
JavaScript objects are unordered by definition. The language specification doesn't even guarantee that, if you iterate over the properties of an object twice in succession, they'll come out in the same order the second time.
If you need things to be ordered, use an array and the Array.prototype.sort method.
That is an object but you can sort an array ilke this:
Working Demo: http://jsfiddle.net/BF8LV/2/
Hope this help,
code
function sortAscending(data_A, data_B)
{
return (data_A - data_B);
}
var array =[ 9, 10, 21, 46, 19, 11]
array.sort(sortAscending)
alert(array);​
Not many people knows that Array.sort can be used on other kinds of objects, but they must have a length property:
array.length = 334;
Array.prototype.sort.call(array, function(a, b) {return a.id - b.id;});
Unfortunately, this doesn't work well if your "array" is full of "holes" like yours.

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