Filtrex aims to make filtering database results with Ecto a breeze. This library attempts to help you solve problems such as...
- Building database query filters from URL parameters
- Establishing a readable, consistent convention for filter parameters
- Validating filters do not expose unintended data or allow unauthorized access
- Saving filters for later use (e.g. a smart filter feature)
Check out the docs or read on for a quick start on how to use.
Note that this library does not require using a web dependency such as Phoenix but is geared towards web applications. It also has only been tested with a Postgres backing but may work with other database adapters.
The package is available on Hex and can be installed by adding it to your list of dependencies:
def deps do
[{:filtrex, "~> 0.4.1"}]
end
- Example Usage
- Filtering from parameters (and an example with phoenix)
- Storing filters
- Configuration
- Filter Types
Here is a simple example of how to filter incoming parameters with filtrex:
# in controller
defmodule MyApp.CommentController do
use MyAppWeb, :controller
def index(conn, params) do
# step 1: convert and validate incoming parameters
{:ok, filter} = MyApp.FilterConfig.comments()
|> Filtrex.parse_params(params)
# step 2: build query
query = MyApp.Comment
|> where([c], c.user_id == ^conn.assigns[:user_id])
|> Filtrex.query(filter)
json conn, Repo.all(query)
end
end
# in lib/my_app/filter_config.ex
defmodule MyApp.FilterConfig do
import Filtrex.Type.Config
# create configuration for transforming / validating parameters
def comments() do
defconfig do
text [:title, :comments]
date :posted_at, format: "{0M}-{0D}-{YYYY}"
end
end
end
# reference model
defmodule MyApp.Comment do
use Ecto.Schema
schema "comments" do
field :title
field :comments
field :posted_at, :date
end
end
With this example, here are some of the query parameters that can be used:
Example Key | Example Value |
---|---|
comments_contains |
Chris McCord |
title |
Upcoming Phoenix Features |
posted_at_between (nested value) |
start: "01-01-2013" end: "12-31-2017" |
filter_union (any | all | none) |
any |
Filtering from parameters is often a tedious process of special keys and validation. Filtrex standardizes this process by using a human-readable format for columns. Consider these examples:
Query Key | Column | Intention |
---|---|---|
comments_is_not |
comments |
!= |
title_contains |
title |
includes text |
rating_greater_than_or |
rating |
>= |
posted_on_or_before |
posted |
<= |
Assuming that these keys are in a map along with the associated values, the parameters can be passed into filtrex with a simple configuration DSL that will validate and parse them effectively. See Configuration for more details on how to create the appropriate config.
# create necesary configuration
import Filtrex.Type.Config
config = defconfig do
text [:title, :comments]
date :posted
number :rating, allow_decimal: true
end
# convert params into a validated filter
case Filtrex.parse_params(config, params) do
{:ok, filter} ->
# use filter to create query
query = Filtrex.query(MyApp.Comment, filter)
{:error, error} ->
# e.g. {:error, "Unknown filter key 'title_means'"}
end
Here is an example of how filtrex might be used within an elixir app that uses phoenix:
# in controller
def index(conn, params = %{"user_id" => user_id}) do
# remove keys that are not filtered against
filter_params = Map.drop(params, ~w(user_id))
# create base query
base_query = from(c in MyApp.Comment, c.user_id == ^user_id)
# create relevant configuration
config = MyApp.Comment.filter_options(:admin)
# parse filter parameters
case Filtrex.parse_params(config, filter_params) do
{:ok, filter} ->
# retrieve from database
render conn, "index.json", data: Filtrex.query(base_query, filter) |> Repo.all
{:error, error} ->
# render filter error
render conn, "errors.json", data: [error]
end
end
# in model-level module
defmodule MyApp.Comment do
import Filtrex.Type.Config
# ...
def filter_options(:admin) do
defconfig do
text :title
date :published
number :upvotes
number :rating, allow_decimal: true
boolean :flag
datetime [:updated_at, :inserted_at]
end
end
end
With this example, a query such as this one would filter comments:
%{
"title_contains" => "Conf",
"published_on_or_before" => "2016-04-01",
"upvotes_greater_than" => 45,
"flag" => true,
"updated_at_after" => "2016-04-01T12:34:56Z",
"rating_greater_than_or" => 90.5,
"filter_union" => "any"
# ^ filter based on any of the columns
}
In addition to parsing parameters, filtrex also enables parsing from a map syntax that is easily encodable to and from JSON. This feature allows storing a filter for future use (e.g. routinely checking for comments that mention "ElixirConf" or todos that are not completed).
# create validation options for keys and formats
import Filtrex.Type.Config
config = defconfig do
text [:title, :comments]
date :due_date
boolean :flag
end
# parse a filter from map syntax
{:ok, filter} = Filtrex.parse(config, %{
"filter" => %{
"type" => "all", # all | any | none
"conditions" => [
%{"column" => "title", "comparator" => "contains", "value" => "Buy", "type" => "text"},
%{"column" => "title", "comparator" => "does not contain", "value" => "Milk", "type" => "text"},
%{"column" => "flag", "comparator" => "equals", "value" => "false", "type" => "boolean"}
],
"sub_filters" => [%{
"filter" => %{
"type" => "any",
"conditions" => [
%{"column" => "due_date", "comparator" => "equals", "value" => "2016-03-26", "type" => "date"}
]
}
}]
}
})
# Encode filter structure into where clause on Ecto query
query = from(m in MyApp.Todo, where: m.rating > 90)
|> Filtrex.query(filter) # => #Ecto.Query<...
For more details on the acceptable structure of this map, feel free to take a look at the example json schema or the raw JSON schema config.
Each of the methods of creating a filter requires passing a configuration that filtrex then validates against. This data structure is really just a list of type configs.
[%Filtrex.Type.Config{keys: ["title", "description"], options: %{}, type: :text},
%Filtrex.Type.Config{keys: ["published"], options: %{}, type: :boolean},
%Filtrex.Type.Config{keys: ["posted_at"], options: %{format: "{YYYY}-{0M}-{0D}"}, type: :date},
%Filtrex.Type.Config{keys: ["updated_at"], options: %{}, type: :datetime},
%Filtrex.Type.Config{keys: ["views"], options: %{allow_decimal: false}, type: :number}]
However, for convenience and for validating the filter types, this DSL can be used to generate that exact data structure.
import Filtrex.Type.Config
defconfig do
# multiple text keys
text [:title, :description]
# boolean type
boolean :published
# date type with options
date :posted_at, format: "{YYYY}-{0M}-{0D}"
# simple datetime
datetime :updated_at
# integer value
number :views, allow_decimal: false
end
The options passed to each type gives the individual condition types more information to validate the filter against and is a required argument. See filter types for details on the available options.
The following condition types and comparators are supported.
- Filtrex.Condition.Boolean
- equals, does not equal
- Filtrex.Condition.Text
- equals, does not equal, contains, does not contain
- Filtrex.Condition.Date
- after, on or after, before, on or before, between, not between, equals, does not equal
- options: format (default:
{YYYY}-{0M}-{0D}
)
- Filtrex.Condition.DateTime
- after, on or after, before, on or before, equals, does not equal
- options: format (default:
{ISOz}
)
- Filtrex.Condition.Number
- equals, does not equal, greater than, less than or, greater than or, less than
- options: allow_decimal (default: false), allowed_values (default: nil)
Copyright (c) 2015-2017 Christian Di Lorenzo
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