Stringify json recursive relationship

javascript - Using recursion to create a JSON string (replicate stringify) - Stack Overflow

stringify json recursive relationship

JSON Bidirectional Relationship Challenge If you try to convert the above parent object to JSON (for example, by using the stringify method, as in . child properties // (note well: recursive call) convertToJsonHelper(obj[i]. toJSON = function(recursive) { var json =; recursive for that - it's quite common to have relations between models and collections, and . for vivifying nested arrays and objects into models and collections at parse time. This method is recursive, so all attributes and all relations (including the relations of relations) To convert a model to JSON, you should use the toJson method.

Some of the filter queries are long, so be sure to scroll all the way to the right when copying them. The results will immediately display on the right-hand side, and update whenever you change the filter or the input JSON.

You do not need to press enter.

JavaScript - JSON Stringify

After each query in this lesson, I will include the first few lines of the expected results, so that you can check your work. In some instances, we will interact with the checkboxes on the upper-right. These set various jq command-line options, or flagsthat affect things like input handling, and the final formatting of the output.

Start the lesson with all of them unchecked.

Bidirectional Relationship Support in JSON - Voxxed

Core jq filters jq operates by way of filters: The basic jq operator is the dot: Add the name of a key to it, however, and the filter will return the value of that key. Try the following filter: The result should read We will use this functionality later in the lesson.

By adding [] onto the end of our filter, jq will break up this one array into 10 separate objects: This removes the cosmetic line breaks in the results, returning one JSON object per line. You should have a line output now.

Sorting An Object Recursively By Key In Node.JS/JavaScript

The results should now be just one line, as jq is now just returning one single JSON array: If you want to access just the first or the n-th item in an array, put a digit in the [] operator: This is because JavaScript, like quite a few other programming languages though not all! This filter returns just the first element of the artObjects array. The magic of jq is that you can connect, or pipe, several operators together to accomplish some very complex transformations of your data. Therefore, while we started with just one big JSON object.

Any operator we put after the will be repeated for each of these objects. For example, try the following query: The sends the results of this step along to the next command… select.

stringify json recursive relationship

Our rule has 3 parts: If it is true, then select will pass the object along to the last part of our filter. If it is false, it will not pass it. This can be useful if you want to output a new JSON file. As we will see below, this can also be a crucial intermediate step when reshaping complex JSON.

stringify json recursive relationship

Create a new set of JSON objects with the following filter: The resulting set of JSON objects have just two keys: The previous filter gave us an array with the id and title keys of each painting. This is a valid CSV file, which we could now import into an analysis program.

Advanced operations JSON vs. Because there is no standard for naming JSON vs. JSON lines files, the only way to check what type you are getting is to open the file in a text editor or use head on the command line to check if the file has one object per line, or is one big object or a series of objects wrapped with [] spread out over many lines.

Bidirectional Relationship Support in JSON

The Rijksmuseum example above is a single JSON object that contains many smaller sub-objects, each of which stands for an artwork in the collection. One of the easiest ways to search and download Twitter data is using the excellent utility twarcwhich saves data as JSON lines. For this lesson, we will use a small sample of 50 public tweets.

Then copy this sample Twitter data into jq play. Tweet hashtags Often you may wish to create a table that expresses a one-to-many relationship, such as a tweet and its hashtags. A tweet will always have exactly one tweet ID, while it may have zero, one, or more hashtags. There are a few ways to express this as a CSV table, but we will implement two common solutions here: Paste this filter into jq play: The value of hashtags is the array wrapped in [] from the original data, which may have 0 or more objects inside it.

Note, however, that tweet ID shows up twice in the results, because it had 2 hashtags: We want the tweet ID to only show up once, with an array of hashtags. If it finds multiple results, it will put them together in the same array.

Note that tweet ID now has just one object, with an embedded array of two hashtags: To do this, we need to add one more intermediary JSON object: However, we change the value of hashtags one last time. There are ways to get the same results using an even shorter query, but in most cases, it pays to break up your jq transformations into small steps.

All we need to do is construct the CSV row arrays and pipe them through the csv operator: Grouping and Counting Often times, your JSON will be structured around one type of entity say, artworks from the Rijksmuseum API, or tweets from the Twitter API when you, the researcher, may be more interested in collecting information about a related, but secondary entity, like an artist, a Twitter hashtag, or a Twitter user.

In this section, we will use jq to extract a table of information about Twitter users from the tweet-based JSON, as well as grouping and counting tweet hashtags.

stringify json recursive relationship

For the previous examples, we have only needed to consider each tweet individually. By default, jq will look at one JSON object at a time when parsing a file; consequently, it can stream very large files without having to load the entire set in to memory.

Fortunately for us, this is pretty simple to do: This is due to the fact that the inner objects are technically different objects. Were we to call either of the above on the inner object, we would get their keys too. Ok, so we now have a list of top-level keys in the object.

Reshaping JSON with jq | Programming Historian

Naturally, the next step is to sort these keys alphabetically, which is also pretty simple. Underscore has a nice method already available for this which makes it pretty easy, but it's also very casual to implement in pure JS.

So now we can see that we've moved from [ 'test', 'colour', 'song', 'profession', 'gender', 'languages', 'relationships' ] to [ 'colour', 'gender', 'languages', 'profession', 'relationships', 'song', 'test' ] We essentially have what we need to start remapping to the new object we're going to return; all we need to do is create a new object and start mapping the keys over in this new order one-by-one. However, there are still a couple of issues, can you spot them?

Firstly, nested objects aren't touched by this code, they're copied as-is as-are? This is a simple problem to solve though, we just put in a check for an object type and then recall the code if it's an object, to sort this too.

Unfortunately though, it isn't this simple. See if you can figure out what's going to go wrong, without seeing the resulting object.

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I'll give you a hint, it involves Arrays. An array is of the Object type, meaning that this too will be run through the sortObjectand because we're using for var x in X syntax Underscore does this under the hood toowe're going to see the indexes in any arrays read as an object key, and it will be translated from an array to an object.