BackboneQuery

BackboneQuery -- Provides client side sorting based on a query API.

Forked from https://github.com/davidgtonge/backbone_query

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.

The huge benefit of using BackboneQuery is that queries can be stored as JSON.

Usage

The major difference of this implementation is that the API is not attached to a collection, but can be run against any collection by invoking the methods with a target collection.

Find

$equal

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

If the attribute in the model is an array then the query value is searched for in the array in the same way as $contains.

If the query value is an object (including array) then a deep comparison is performed using underscores _.isEqual.

Example:

BackboneQuery.find(collection, { title: "Test" });
// Returns all models which have a "title" attribute of "Test"


BackboneQuery.find(collection, { title: { $equal: "Test" } }); // Same as above
BackboneQuery.find(collection, { colors: "red" });
// Returns models which contain the value "red" in a "colors" attribute that is an array.


BackboneQuery.find(collection, { colors: ["red", "yellow"] });
// Returns models which contain a colors attribute with the array ["red", "yellow"]

$contains

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

Example:

BackboneQuery.find(collection, { 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

Example:

BackboneQuery.find(collection, { 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

Example:

BackboneQuery.find(collection, { likes: { $lt:10 } });
// Returns all models which have a "likes" attribute of less than 10


BackboneQuery.find(collection, { likes: { $lte:10 } });
// Returns all models which have a "likes" attribute of less than or equal to 10


BackboneQuery.find(collection, { likes: { $gt:10 } });
// Returns all models which have a "likes" attribute of greater than 10


BackboneQuery.find(collection, { 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.

Example:

BackboneQuery.find(collection, { 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.

Example:

BackboneQuery.find(collection, { 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.

Example:

BackboneQuery.find(collection, { 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.

Example:

BackboneQuery.find(collection, { 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.

Example:

BackboneQuery.find(collection, { 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.

Example:

BackboneQuery.find(collection, { 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.

Example:

BackboneQuery.find(collection, { title: { $exists: true } });

// Returns all models which have a "title" attribute

BackboneQuery.find(collection, { 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.

Example:

BackboneQuery.find(collection, { 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).

Example:

BackboneQuery.find(collection, { 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.

Example:

BackboneQuery.find(collection, { content: { $regex: /coffeescript/gi } });

// Checks for a regex match in the content attribute

BackboneQuery.find(collection, { 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.

Example:

BackboneQuery.find(collection, { title: { $cb: function(attr){ return attr.charAt(0) === "c"; } } });

// Returns all models that have a title attribute that starts with "c"

BackboneQuery.find(collection, { 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 Collection.filter. However if you are performing other tests or are using the paging / sorting / caching options of backbone query, then this functionality is useful.

$elemMatch

This operator allows you to perform queries in nested arrays similar to MongoDB For example you may have a collection of models in with this kind of data structure:

Example:

let posts = new Collection([

{title: "Home", comments:[

  {text:"I like this post"},

  {text:"I love this post"},

  {text:"I hate this post"}

]},

{title: "About", comments:[

  {text:"I like this page"},

  {text:"I love this page"},

  {text:"I really like this page"}

]}

]);

To search for posts which have the text "really" in any of the comments you could search like this:

BackboneQuery.find(posts, {

comments: {

  $elemMatch: {

     text: /really/i

  }

}

});

All of the operators above can be performed on $elemMatch queries, e.g. $all, $size or $lt. $elemMatch queries also accept compound operators, for example this query searches for all posts that have at least one comment without the word "really" and with the word "totally".

BackboneQuery.find(posts, {

comments: {

  $elemMatch: {

     $not: {

        text: /really/i

     },

     $and: {

        text: /totally/i

     }
  }

}

});

$computed

This operator allows you to perform queries on computed properties. For example you may want to perform a query for a persons full name, even though the first and last name are stored separately in your db / model. For example:

Example:

class TestModel extends Backbone.Model {

full_name() {

  return (this.get('first_name')) + " " + (this.get('last_name'));

}

});

let a = new TestModel({

first_name: "Dave",

last_name: "Tonge"

});

let b = new TestModel({

first_name: "John",

last_name: "Smith"

});

let collection = new Collection([a, b]);

BackboneQuery.find(collection, { full_name: { $computed: "Dave Tonge" } });

// Returns the model with the computed full_name equal to Dave Tonge

BackboneQuery.find(collection, { full_name: { $computed: { $likeI: "john smi" } } });

// Any of the previous operators can be used (including elemMatch is required)

Combined Queries

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

$and

BackboneQuery.find(collection, { $and: { title: { $like: "News" }, likes: { $gt: 10 }}});

// Returns all models that contain "News" in the title and have more than 10 likes.

BackboneQuery.find(collection, { title: { $like: "News" }, likes: { $gt: 10 } });

// Same as above as $and is assumed if not supplied

$or

BackboneQuery.find(collection, { $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

BackboneQuery.find(collection, { $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

BackboneQuery.find(collection, { $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.

If you need to perform multiple queries on the same key, then you can supply the query as an array:

BackboneQuery.find(collection, {

$or:[

  {title:"News"},

  {title:"About"}

]

});

// Returns all models with the title "News" or "About".

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".

BackboneQuery.find(collection, {

$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.

BackboneQuery.find(collection, { title: { $like: "News" } }, { sortBy: "likes" });

// Returns all models that contain "News" in the title, sorted according to their "likes" attribute (ascending)

BackboneQuery.find(collection, { title: { $like: "News" } }, { sortBy: "likes", order: "desc" });

// Same as above, but "descending"

BackboneQuery.find(collection,

{ 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.

BackboneQuery.find(collection, { likes:{ $gt: 10 } }, { limit: 10 });

// Returns the first 10 models that have more than 10 likes.

BackboneQuery.find(collection, { likes:{ $gt: 10 } }, { limit: 10, offset: 5 });

// Returns 10 models that have more than 10 likes starting at the 6th model in the results.

BackboneQuery.find(collection, { 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 an example of a simple paging setup using the pager callback option:

TODO Provide example!

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.

BackboneQuery.find(collection, { likes:{ $gt: 10 } }, { limit: 10, page: 1, cache: true });
//The first query will operate as normal and return the first page of results

BackboneQuery.find(collection, { 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 parameters are applied.

// Binding the reset_query_cache method
MyCollection extends Backbone.Collection {
   initialize() {
      this.bind("change", () => { BackboneQuery.resetQueryCache(this) }, this);
   }
});