Bind

Flexible and dynamic Ecto query builder for Elixir applications, allowing developers to retrieve data flexibly without writing custom queries for each use case.

Installation

Add bind to your list of dependencies in mix.exs:

def deps do
  [
    {:bind, "~> 0.1.1"}
  ]
end

API

Bind.query(schema, params)

Parameters:

• schema: The Ecto schema module (e.g., MyApp.User).
• params: Either a map of query parameters or a query string.

Returns: An Ecto query.

Usage Example

Create Ecto query:

query = Bind.query(MyApp.User, %{ "name[eq]" => "Alice", "age[gte]" => 30 })

Alternatively, with a query string:

query = Bind.query(MyApp.User, "?name[eq]=Alice&age[gte]=30")

And finally run the query to get results from the database:

results = Repo.all(query)

Error handling

case Bind.query(MyApp.User, %{ "name[eq]" => "Alice", "age[gte]" => 30 }) do
  {:error, reason} ->
    IO.puts("Error building query: #{reason}")

  query ->
    results = Repo.all(query)
end

Filtering

Examples:

%{"name[eq]" => "Alice", "age[gte]" => 30}

%{
  "name[starts_with]" => "A",
  "age[gte]" => 18,
  "role[in]" => "superuser,admin,mod",
  "is_active[true]" => "",
  "last_login[nil]" => false
}

List of comparison operators supported:

• eq: Equal to
• neq: Not equal to
• gt: Greater than
• gte: Greater than or equal to
• lt: Less than
• lte: Less than or equal to
• true: Boolean true
• false: Boolean false
• starts_with: String starts with
• ends_with: String ends with
• in: In a list of values
• contains: String contains
• nil: Is nil (or is not nil)

Sorting

Use the sort parameter to specify sorting order:

• Prefix with - for descending order
• No prefix for ascending order

%{"sort" => "-age"}  # Sort by age descending
%{"sort" => "age"}  # Sort by age ascending

If nothing specified, sorts by ID field ascending.

Pagination

• limit: Specify the maximum number of results (default: 10)
• start: Specify the starting ID for pagination

Example:

%{"limit" => 20, "start" => 100}

Query String Support

Bind can also pass URL query strings:

query_string = "?name[eq]=Alice&age[gte]=30&sort=-age&limit=10"
query = Bind.query(MyApp.User, query_string)

Using with Phoenix

When using with Phoenix, use raw query string instead of params and decode it first; URI.decode_query(conn.query_string).

Example controller method:

def index(conn, params) do
    query = Bind.query(Waitlist, URI.decode_query(conn.query_string))
    requests = Mitte.Repo.all(query)
    render(conn, :index, requests: requests)
end