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A lightweight query api for Backbone Collections

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README.md

backbone-query

Build Status

A lightweight (3KB minified) utility for Backbone projects, that works in the Browser and on the Server. Adds the ability to search for models with a Query API similar to MongoDB Please report any bugs, feature requests in the issue tracker. Pull requests are welcome!

Usage

Client Side Installation:

To install, include the js/backbone-query.min.js file in your HTML page, after Backbone and it's dependencies. Then extend your collections from Backbone.QueryCollection rather than from Backbone.Collection.

Server side (node.js) installation

You can install with NPM: npm install backbone-query Then simply require in your project: QueryCollection = require("backbone-query").QueryCollection

Your collections will now have two new methods: query and where. Both methods accept 2 arguments - a query object and an options object. The query method returns an array of models, but the where method returns a new collection and is therefore useful where you would like to chain multiple collection methods / where queries (thanks to @cezary). The following are some basic examples:

MyCollection.query({ 
    featured:true, 
    likes: {$gt:10}
});
// Returns all models where the featured attribute is true and there are
// more than 10 likes

MyCollection.query(
    {tags: { $any: ["coffeescript", "backbone", "mvc"]}},
    {sortBy: "likes", order: "desc", limit:10, page:2, cache:true}
);
// Finds models that have either "coffeescript", "backbone", "mvc" in their "tags" attribute
// Sorts these models by the "likes" attribute in descending order
// Caches the results and returns only 10 models, starting from the 11th model (page 2)

MyCollection.query({
  // Models must match all these queries
  $and:{
    title: {$like: "news"}, // Title attribute contains the string "news"
    likes: {$gt: 10}
  }, // Likes attribute is greater than 10

  // Models must match one of these queries
  $or:{
    featured: true, // Featured attribute is true
    category:{$in:["code","programming","javascript"]}
  } 
  //Category attribute is either "code", "programming", or "javascript"
});

Or if CoffeeScript is your thing (the source is written in CoffeeScript), try this:

MyCollection.query
  $and:
    likes: $lt: 15
  $or:
    content: $like: "news"
    featured: $exists: true
  $not:
    colors: $contains: "yellow"

Another CoffeeScript example, this time using where rather than query

query = 
  $likes: $lt: 10
  $downloads: $gt: 20

MyCollection.where(query).my_custom_collection_method()

Query API

$equal

Performs a strict equality test using ===. If no operator is provided and the query value isn't a regex then $equal is assumed.

MyCollection.query({ title:"Test" });
// Returns all models which have a "title" attribute of "Test"

MyCollection.query({ title: {$equal:"Test"} }); // Same as above

$contains

Assumes that the model property is an array and searches for the query value in the array

MyCollection.query({ colors: {$contains: "red"} });
// Returns models which contain the value "red" in a "colors" attribute that is an array.
// e.g. a model with this attribute colors:["red","yellow","blue"] would be returned

$ne

"Not equal", the opposite of $equal, returns all models which don't have the query value

MyCollection.query({ title: {$ne:"Test"} });
// Returns all models which don't have a "title" attribute of "Test"

$lt, $lte, $gt, $gte

These conditional operators can be used for greater than and less than comparisons in queries

MyCollection.query({ likes: {$lt:10} });
// Returns all models which have a "likes" attribute of less than 10
MyCollection.query({ likes: {$lte:10} });
// Returns all models which have a "likes" attribute of less than or equal to 10
MyCollection.query({ likes: {$gt:10} });
// Returns all models which have a "likes" attribute of greater than 10
MyCollection.query({ likes: {$gte:10} });
// Returns all models which have a "likes" attribute of greater than or equal to 10

$between

To check if a value is in-between 2 query values use the $between operator and supply an array with the min and max value

MyCollection.query({ likes: {$between:[5,15} });
// Returns all models which have a "likes" attribute of greater than 5 and less then 15

$in

An array of possible values can be supplied using $in, a model will be returned if any of the supplied values is matched

MyCollection.query({ title: {$in:["About", "Home", "Contact"] } });
// Returns all models which have a title attribute of either "About", "Home", or "Contact"

$nin

"Not in", the opposite of $in. A model will be returned if none of the supplied values is matched

MyCollection.query({ title: {$nin:["About", "Home", "Contact"] } });
// Returns all models which don't have a title attribute of either
// "About", "Home", or "Contact"

$all

Assumes the model property is an array and only returns models where all supplied values are matched.

MyCollection.query({ colors: {$all:["red", "yellow"] } });
// Returns all models which have "red" and "yellow" in their colors attribute.
// A model with the attribute colors:["red","yellow","blue"] would be returned
// But a model with the attribute colors:["red","blue"] would not be returned

$any

Assumes the model property is an array and returns models where any of the supplied values are matched.

MyCollection.query({ colors: {$any:["red", "yellow"] } });
// Returns models which have either "red" or "yellow" in their colors attribute.

$size

Assumes the model property has a length (i.e. is either an array or a string). Only returns models the model property's length matches the supplied values

MyCollection.query({ colors: {$size:2 } });
// Returns all models which 2 values in the colors attribute

$exists or $has

Checks for the existence of an attribute. Can be supplied either true or false.

MyCollection.query({ title: {$exists: true } });
// Returns all models which have a "title" attribute
MyCollection.query({ title: {$has: false } });
// Returns all models which don't have a "title" attribute

$like

Assumes the model attribute is a string and checks if the supplied query value is a substring of the property. Uses indexOf rather than regex for performance reasons

MyCollection.query({ title: {$like: "Test" } });
//Returns all models which have a "title" attribute that
//contains the string "Test", e.g. "Testing", "Tests", "Test", etc.

$likeI

The same as above but performs a case insensitive search using indexOf and toLowerCase (still faster than Regex)

MyCollection.query({ title: {$likeI: "Test" } });
//Returns all models which have a "title" attribute that
//contains the string "Test", "test", "tEst","tesT", etc.

$regex

Checks if the model attribute matches the supplied regular expression. The regex query can be supplied without the $regex keyword

MyCollection.query({ content: {$regex: /coffeescript/gi } });
// Checks for a regex match in the content attribute
MyCollection.query({ content: /coffeescript/gi });
// Same as above

$cb

A callback function can be supplied as a test. The callback will receive the attribute and should return either true or false. this will be set to the current model, this can help with tests against computed properties

MyCollection.query({ title: {$cb: function(attr){ return attr.charAt(0) === "c";}} });
// Returns all models that have a title attribute that starts with "c"

MyCollection.query({ computed_test: {$cb: function(){ return this.computed_property() > 10;}} });
// Returns all models where the computed_property method returns a value greater than 10.

For callbacks that use this rather than the model attribute, the key name supplied is arbitrary and has no effect on the results. If the only test you were performing was like the above test it would make more sense to simply use MyCollection.filter. However if you are performing other tests or are using the paging / sorting / caching options of backbone query, then this functionality is useful.

Combined Queries

Multiple queries can be combined together. By default all supplied queries must be matched $and. However it is possible to specify either $or, $nor, $not to implement alternate logic.

$and

MyCollection.query({ $and: { title: {$like: "News"}, likes: {$gt: 10}}});
// Returns all models that contain "News" in the title and have more than 10 likes.
MyCollection.query({ title: {$like: "News"}, likes: {$gt: 10} });
// Same as above as $and is assumed if not supplied

$or

MyCollection.query({ $or: { title: {$like: "News"}, likes: {$gt: 10}}});
// Returns all models that contain "News" in the title OR have more than 10 likes.

$nor

The opposite of $or

MyCollection.query({ $nor: { title: {$like: "News"}, likes: {$gt: 10}}});
// Returns all models that don't contain "News" in the title NOR have more than 10 likes.

$not

The opposite of $and

MyCollection.query({ $not: { title: {$like: "News"}, likes: {$gt: 10}}});
// Returns all models that don't contain "News" in the title AND DON'T have more than 10 likes.

Compound Queries

It is possible to use multiple combined queries, for example searching for models that have a specific title attribute, and either a category of "abc" or a tag of "xyz"

MyCollection.query({
    $and: { title: {$like: "News"}},
    $or: {likes: {$gt: 10}, color:{$contains:"red"}}
});
//Returns models that have "News" in their title and
//either have more than 10 likes or contain the color red.

Sorting

Optional sortBy and order attributes can be supplied as part of an options object. sortBy can either be a model key or a callback function which will be called with each model in the array.

MyCollection.query({title: {$like: "News"}}, {sortBy: "likes"});
// Returns all models that contain "News" in the title,
// sorted according to their "likes" attribute (ascending)

MyCollection.query({title: {$like: "News"}}, {sortBy: "likes", order:"desc"});
// Same as above, but "descending"
MyCollection.query(
    {title: {$like: "News"}},
    {sortBy: function(model){ return model.get("title").charAt(1);}}
);
// Results sorted according to 2nd character of the title attribute

Paging

To return only a subset of the results paging properties can be supplied as part of an options object. A limit property must be supplied and optionally a offset or a page property can be supplied.

MyCollection.query({likes:{$gt:10}}, {limit:10});
// Returns the first 10 models that have more than 10 likes

MyCollection.query({likes:{$gt:10}}, {limit:10, offset:5});
// Returns 10 models that have more than 10 likes starting
//at the 6th model in the results

MyCollection.query({likes:{$gt:10}}, {limit:10, page:2});
// Returns 10 models that have more than 10 likes starting
//at the 11th model in the results (page 2)

When using the paging functionality, you will normally need to know the number of pages so that you can render the correct interface for the user. Backbone Query can send the number of pages of results to a supplied callback. The callback should be passed as a pager property on the options object. This callback will also receive the sliced models as a second variable.

Here is a coffeescript example of a simple paging setup using the pager callback option:

class MyView extends Backbone.View
    initialize: ->
        @template = -> #templating setup here

    events:
        "click .page": "change_page"

    query_collection: (page = 1) ->
        #Collection should be passed in when the view is instantiated
        @collection.query {category:"javascript"}, {limit:5, page:page, pager:@render_pages}

    change_page: (e) =>
        page_number = $(e.target).data('page_number')
        @query_collection page_number

    render_pages: (total_pages, results) =>
        content = @template results
        pages = [1..total_pages]
        nav = """
        <nav>
            <span>Total Pages: #{total_pages}</span>
        """
        for page in pages
          nav += "<a href='#' data-page_number='#{page}'>#{page}</a>"

        nav += "</nav>"

        @$el.html content + nav

    render: => @query_collection()

Caching Results

To enable caching set the cache flag to true in the options object. This can greatly improve performance when paging through results as the unpaged results will be saved. This options is not enabled by default as if models are changed, added to, or removed from the collection, then the query cache will be out of date. If you know that your data is static and won't change then caching can be enabled without any problems. If your data is dynamic (as in most Backbone Apps) then a helper cache reset method is provided: reset_query_cache. This method should be bound to your collections change, add and remove events (depending on how your data can be changed).

Cache will be saved in a _query_cache property on each collection where a cache query is performed.

MyCollection.query({likes:{$gt:10}}, {limit:10, page:1, cache:true});
//The first query will operate as normal and return the first page of results
MyCollection.query({likes:{$gt:10}}, {limit:10, page:2, cache:true});
//The second query has an identical query object to the first query, so therefore the results will be retrieved
//from the cache, before the paging paramaters are applied.

// Binding the reset_query_cache method
var MyCollection = Backbone.QueryCollection.extend({
    initialize: function(){
        this.bind("change", this.reset_query_cache, this);
    }
});


Author

Dave Tonge - davidgtonge

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