CODEWITHSUNDEEP
jsonnode.jsmongodbnedb
user2565677
user2565677

Reputation: 905

Accessing nedb results

The question is: how to access multiple documents returned from a nedb 'find' command.

Understanding some insight I gained using nedb in nodejs.

Regarding docs returned via nedb find and accessing key value pair: Thought this would work: docs.current.temp_f but it doesn't. This works: docs[0].current.temp_f does work.

Background and detail: I'm new to JavaScript, nodejs, nedb, and have never used mongodb, but understand nedb has a similar API.

The reason for my post is: I use this site a lot, but could not find an answer to my problem. I finally figured it out myself, and am posting it here so I can return a contribution to the community.

I'm accessing Wunderground using their API. Works great. I then pushed the results into nedb using the nedb API's 'insert' command. There are multiple examples of this available, here and elsewhere.

Using the nedb API's find command, I was able to retrieve my data. I could print it out using console.log(). Again, multiple examples here and elsewhere for this.

Wunderground returns a JSON object (if requested in this format), in the form {response:{...some data}, current_observation:{...some data...temp_f...some more data}}, which can be inserted into the nedb database.

Using the nedb API 'find' command (e.g.,

db.find({},function(err,docs) {console.log(docs);} I was able to print out my data. But my desire was to just obtain a few key:value pairs, not the whole structure. I thought that something like docs.current_observation.temp_f would do the trick, but this was always 'undefined' and caused an error.

What I didn't understand, because I'm so new in this area, is that nedb is returning a "set" of data; an array of JSON objects in this case, since I was inserting JSON objects. I never saw this mentioned anywhere on the npmjs.com site for nedb. So I wanted to alert others like myself that lacked this knowledge.

Here's what ultimately worked to obtain the key:value information: console.log("temp_f: ", docs[0].current_observation.temp_f);
where I'm accessing the array element 0.

Of course, this would probably end up in something like a for/in loop.

I would be interested in seeing any additional ideas on retrieving key:values from the result set returned, if you know of any.

//Thought this would work, but it doesn't
docs.current_observation.temp_f
//but this does, where x is a value to record
docs[x].current_observation.temp_f

Upvotes: 0

Views: 1944

Answers (1)

simon-p-r
simon-p-r

Reputation: 3751

Simple answer is use mongo's query language with find method to return an array of matching documents then manipulate the array of objects to get the values you need. Use for of when iterating arrays not for in. Alternatively use map, filter, forEach and reduce array methods for manipulating array data.

Upvotes: 2

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