Phoenix.HTML v2.10.2 Phoenix.HTML.Form View Source

Helpers related to producing HTML forms.

The functions in this module can be used in three distinct scenarios:

  • with changeset data - when information to populate the form comes from a changeset

  • with connection data - when a form is created based on the information in the connection (aka Plug.Conn)

  • without form data - when the functions are used directly, outside of a form

We will explore all three scenarios below.

With changeset data

The entry point for defining forms in Phoenix is with the form_for/4 function. For this example, we will use Ecto.Changeset, which integrate nicely with Phoenix forms via the phoenix_ecto package.

Imagine you have the following action in your controller:

def new(conn, _params) do
  changeset = User.changeset(%User{})
  render conn, "new.html", changeset: changeset
end

where User.changeset/2 is defined as follows:

def changeset(user, params \\ %{}) do
  cast(user, params, [:name, :age])
end

Now a @changeset assign is available in views which we can pass to the form:

<%= form_for @changeset, user_path(@conn, :create), fn f -> %>
  <label>
    Name: <%= text_input f, :name %>
  </label>

  <label>
    Age: <%= select f, :age, 18..100 %>
  </label>

  <%= submit "Submit" %>
<% end %>

form_for/4 receives the Ecto.Changeset and converts it to a form, which is passed to the function as the argument f. All the remaining functions in this module receive the form and automatically generate the input fields, often by extracting information from the given changeset. For example, if the user had a default value for age set, it will automatically show up as selected in the form.

A note on :errors

If no action has been applied to the changeset, no errors are shown on the form object even if the changeset has a non-empty :errors value.

This is useful for things like validation hints on form fields, e.g. an empty changeset for a new form. That changeset isn’t valid, but we don’t want to show errors until an actual user action has been performed.

Ecto automatically applies the action for you when you call Repo.insert/update/delete, but if you want to show errors manually you can also set the action yourself, either directly on the Ecto.Changeset struct field or by using Ecto.Changeset.apply_action/2.

With connection data

form_for/4 expects as first argument any data structure that implements the Phoenix.HTML.FormData protocol. By default, Phoenix implements this protocol for Plug.Conn, allowing us to create forms based only on connection information.

This is useful when you are creating forms that are not backed by any kind of data from the data layer, like a search form.

<%= form_for @conn, search_path(@conn, :new), [as: :search], fn f -> %>
  <%= text_input f, :for %>
  <%= submit "Search" %>
<% end %>

form_for/4 uses the Plug.Conn to set input values from the request parameters. In this case, the input’s value would be set to @conn.params["search"]["for"].

Without form data

Sometimes we may want to generate a text_input/3 or any other tag outside of a form. The functions in this module also support such usage by simply passing an atom as first argument instead of the form.

<%= text_input :user, :name, value: "This is a prepopulated value" %>

Nested inputs

If your data layer supports embedding or nested associations, you can use inputs_for to attach nested data to the form.

Imagine the following Ecto schemas:

defmodule User do
  use Ecto.Schema

  schema "users" do
    field :name
    embeds_one :permalink, Permalink
  end
end

defmodule Permalink do
  use Ecto.Schema

  embedded_schema do
    field :url
  end
end

In the form, you now can:

<%= form_for @changeset, user_path(@conn, :create), fn f -> %>
  <%= text_input f, :name %>

  <%= inputs_for f, :permalink, fn fp -> %>
    <%= text_input fp, :url %>
  <% end %>
<% end %>

The default option can be given to populate the fields if none is given:

<%= inputs_for f, :permalink, [default: %Permalink{title: "default"}], fn fp -> %>
  <%= text_input fp, :url %>
<% end %>

inputs_for/4 can be used to work with single entities or collections. When working with collections, :prepend and :append can be used to add entries to the collection stored in the changeset.

Link to this section Summary

Functions

Defines the Phoenix.HTML.Form struct

Generates a checkbox

Generates a color input

Generates select tags for date

Generates select tags for datetime

Generates an email input

Generates a file input

Generates a form tag with a form builder

Generates a hidden input

Converts an attribute/form field into its humanize version

Returns an id of a corresponding form field

Returns a name of a corresponding form field

Returns the HTML5 validations that would apply to the given field

Returns a value of a corresponding form field

Generate a new form builder for the given parameter in form

Generates a label tag

Generates a select tag with the given options

Generates a number input

Generates a password input

Generates a range input

Generates a reset input to reset all the form fields to their original state

Generates a search input

Generates a select tag with the given options

Generates a submit button to send the form

Generates a telephone input

Generates a text input

Generates a textarea input

Generates select tags for time

Generates an url input

Link to this section Types

Link to this type t() View Source
t() :: %Phoenix.HTML.Form{data: %{optional(atom) => term}, errors: Keyword.t, hidden: Keyword.t, id: String.t, impl: module, index: nil | non_neg_integer, name: String.t, options: Keyword.t, params: %{optional(binary) => term}, source: Phoenix.HTML.FormData.t}

Link to this section Functions

Link to this function %Phoenix.HTML.Form{} View Source (struct)

Defines the Phoenix.HTML.Form struct.

Its fields are:

  • :source - the data structure given to form_for/4 that implements the form data protocol

  • :impl - the module with the form data protocol implementation. This is used to avoid multiple protocol dispatches.

  • :id - the id to be used when generating input fields

  • :name - the name to be used when generating input fields

  • :data - the field used to store lookup data

  • :params - the parameters associated to this form in case they were sent as part of a previous request

  • :hidden - a keyword list of fields that are required for submitting the form behind the scenes as hidden inputs

  • :options - a copy of the options given when creating the form via form_for/4 without any form data specific key

  • :errors - a keyword list of errors that associated with the form

Link to this function checkbox(form, field, opts \\ []) View Source

Generates a checkbox.

This function is useful for sending boolean values to the server.

Examples

# Assuming form contains a User schema
checkbox(form, :famous)
#=> <input name="user[famous]" type="hidden" value="false">
    <input checked="checked" id="user_famous" name="user[famous]" type="checkbox" value="true">

Options

  • :checked_value - the value to be sent when the checkbox is checked. Defaults to “true”

  • :unchecked_value - the value to be sent when the checkbox is unchecked, Defaults to “false”

  • :value - the value used to check if a checkbox is checked or unchecked. The default value is extracted from the form data if available

All other options are forwarded to the underlying HTML tag.

Hidden fields

Because an unchecked checkbox is not sent to the server, Phoenix automatically generates a hidden field with the unchecked_value before the checkbox field to ensure the unchecked_value is sent when the checkbox is not marked.

Link to this function color_input(form, field, opts \\ []) View Source

Generates a color input.

Warning: this feature isn’t available in all browsers. Check http://caniuse.com/#feat=input-color for further informations.

See text_input/3 for example and docs.

Link to this function date_select(form, field, opts \\ []) View Source

Generates select tags for date.

Check datetime_select/3 for more information on options and supported values.

Link to this function datetime_select(form, field, opts \\ []) View Source

Generates select tags for datetime.

Examples

# Assuming form contains a User schema
datetime_select form, :born_at
#=> <select id="user_born_at_year" name="user[born_at][year]">...</select> /
    <select id="user_born_at_month" name="user[born_at][month]">...</select> /
    <select id="user_born_at_day" name="user[born_at][day]">...</select> —
    <select id="user_born_at_hour" name="user[born_at][hour]">...</select> :
    <select id="user_born_at_min" name="user[born_at][minute]">...</select>

If you want to include the seconds field (hidden by default), pass second: []:

# Assuming form contains a User schema
datetime_select form, :born_at, second: []

If you want to configure the years range:

# Assuming form contains a User schema
datetime_select form, :born_at, year: [options: 1900..2100]

You are also able to configure :month, :day, :hour, :minute and :second. All options given to those keys will be forwarded to the underlying select. See select/4 for more information.

Options

  • :value - the value used to select a given option. The default value is extracted from the form data if available

  • :default - the default value to use when none was given in :value and none is available in the form data

  • :year, :month, :day, :hour, :minute, :second - options passed to the underlying select. See select/4 for more information. The available values can be given in :options.

  • :builder - specify how the select can be build. It must be a function that receives a builder that should be invoked with the select name and a set of options. See builder below for more information.

Builder

The generated datetime_select can be customized at will by providing a builder option. Here is an example from EEx:

<%= datetime_select form, :born_at, builder: fn b -> %>
  Date: <%= b.(:day, []) %> / <%= b.(:month, []) %> / <%= b.(:year, []) %>
  Time: <%= b.(:hour, []) %> : <%= b.(:minute, []) %>
<% end %>

Although we have passed empty lists as options (they are required), you could pass any option there and it would be given to the underlying select input.

In practice, we recommend you to create your own helper with your default builder:

def my_datetime_select(form, field, opts \\ []) do
  builder = fn b ->
    ~e"""
    Date: <%= b.(:day, []) %> / <%= b.(:month, []) %> / <%= b.(:year, []) %>
    Time: <%= b.(:hour, []) %> : <%= b.(:minute, []) %>
    """
  end

  datetime_select(form, field, [builder: builder] ++ opts)
end

Then you are able to use your own datetime_select throughout your whole application.

Supported date values

The following values are supported as date:

  • a map containing the year, month and day keys (either as strings or atoms)
  • a tuple with three elements: {year, month, day}
  • nil

Supported time values

The following values are supported as time:

  • a map containing the hour and min keys and an optional sec key (either as strings or atoms)
  • a tuple with three elements: {hour, min, sec}
  • a tuple with four elements: {hour, min, sec, usec}
  • nil
Link to this function email_input(form, field, opts \\ []) View Source

Generates an email input.

See text_input/3 for example and docs.

Link to this function file_input(form, field, opts \\ []) View Source

Generates a file input.

It requires the given form to be configured with multipart: true when invoking form_for/4, otherwise it fails with ArgumentError.

See text_input/3 for example and docs.

Generates a form tag with a form builder.

See the module documentation for examples of using this function.

Options

  • :as - the server side parameter in which all params for this form will be collected (i.e. as: :user_params would mean all fields for this form will be accessed as conn.params.user_params server side). Automatically inflected when a changeset is given.

  • :method - the HTTP method. If the method is not “get” nor “post”, an input tag with name _method is generated along-side the form tag. Defaults to “post”.

  • :multipart - when true, sets enctype to “multipart/form-data”. Required when uploading files

  • :csrf_token - for “post” requests, the form tag will automatically include an input tag with name _csrf_token. When set to false, this is disabled

  • :enforce_utf8 - the form will have an accept-charset attribute set to “UTF-8” and a hidden input named _utf8 containing a unicode character to force the browser to use UTF-8 as the charset. When set to false, this is disabled.

  • Other options will be passed as html attributes. ie, class: "foo", id: "bar"

See Phoenix.HTML.Tag.form_tag/2 for more information on the options above.

Link to this function hidden_input(form, field, opts \\ []) View Source

Generates a hidden input.

See text_input/3 for example and docs.

Converts an attribute/form field into its humanize version.

iex> humanize(:username)
"Username"
iex> humanize(:created_at)
"Created at"
iex> humanize("user_id")
"User"

Returns an id of a corresponding form field.

The form should either be a Phoenix.HTML.Form emitted by form_for or an atom.

Returns a name of a corresponding form field.

The form should either be a Phoenix.HTML.Form emitted by form_for or an atom.

Link to this function input_type(form, field, mapping \\ %{"email" => :email_input, "password" => :password_input, "search" => :search_input, "url" => :url_input}) View Source

Gets the input type for a given field.

If the underlying input type is a :text_field, a mapping could be given to further inflect the input type based solely on the field name. The default mapping is:

%{"url"      => :url_input,
  "email"    => :email_input,
  "search"   => :search_input,
  "password" => :password_input}
Link to this function input_validations(form, field) View Source
input_validations(t, atom) :: Keyword.t

Returns the HTML5 validations that would apply to the given field.

Link to this function input_value(form, field) View Source

Returns a value of a corresponding form field.

The form should either be a Phoenix.HTML.Form emitted by form_for or an atom.

When a form is given, it will lookup for changes and then fallback to parameters and finally fallback to the default struct/map value.

Link to this function inputs_for(form, field, options \\ [], fun) View Source
inputs_for(t, atom, Keyword.t, (t -> Phoenix.HTML.unsafe)) :: Phoenix.HTML.safe

Generate a new form builder for the given parameter in form.

See the module documentation for examples of using this function.

Options

  • :id - the id to be used in the form, defaults to the concatenation of the given field to the parent form id

  • :as - the name to be used in the form, defaults to the concatenation of the given field to the parent form name

  • :default - the value to use if none is available

  • :prepend - the values to prepend when rendering. This only applies if the field value is a list and no parameters were sent through the form.

  • :append - the values to append when rendering. This only applies if the field value is a list and no parameters were sent through the form.

Generates a label tag.

The form should either be a Phoenix.HTML.Form emitted by form_for or an atom.

All given options are forwarded to the underlying tag. A default value is provided for for attribute but can be overriden if you pass a value to the for option. Text content would be inferred from field if not specified.

Examples

# Assuming form contains a User schema
label(form, :name, "Name")
#=> <label for="user_name">Name</label>

label(:user, :email, "Email")
#=> <label for="user_email">Email</label>

label(:user, :email)
#=> <label for="user_email">Email</label>

label(:user, :email, class: "control-label")
#=> <label for="user_email" class="control-label">Email</label>

label :user, :email do
  "E-mail Address"
end
#=> <label for="user_email">E-mail Address</label>

label :user, :email, class: "control-label" do
  "E-mail Address"
end
#=> <label class="control-label" for="user_email">E-mail Address</label>
Link to this function label(form, field, text) View Source

See label/2.

Link to this function label(form, field, text, opts) View Source

See label/2.

Link to this function multiple_select(form, field, options, opts \\ []) View Source

Generates a select tag with the given options.

Values are expected to be an Enumerable containing two-item tuples (like maps and keyword lists) or any Enumerable where the element will be used both as key and value for the generated select.

Examples

# Assuming form contains a User schema
multiple_select(form, :roles, ["Admin": 1, "Power User": 2])
#=> <select id="user_roles" name="user[roles][]">
    <option value="1">Admin</option>
    <option value="2">Power User</option>
    </select>

multiple_select(form, :roles, ["Admin": 1, "Power User": 2], selected: [1])
#=> <select id="user_roles" name="user[roles][]">
    <option value="1" selected="selected">Admin</option>
    <option value="2">Power User</option>
    </select>

When working with structs, associations and embeds, you will need to tell Phoenix how to extract the value out of the collection. For example, imagine user.roles is a list of %Role{} structs. You must call it as:

multiple_select(form, :roles, ["Admin": 1, "Power User": 2],
                selected: Enum.map(@user.roles, &(&1.id))

The :selected option will mark the given IDs as selected unless the form is being resubmitted. When resubmitted, it uses the form params as values.

Options

  • :selected - the default options to be marked as selected. The values on this list are ignored in case ids have been set as parameters.

All other options are forwarded to the underlying HTML tag.

Link to this function number_input(form, field, opts \\ []) View Source

Generates a number input.

See text_input/3 for example and docs.

Link to this function password_input(form, field, opts \\ []) View Source

Generates a password input.

For security reasons, the form data and parameter values are never re-used in password_input/3. Pass the value explicitly if you would like to set one.

See text_input/3 for example and docs.

Link to this function radio_button(form, field, value, opts \\ []) View Source

Generates a radio button.

Invoke this function for each possible value you want to be sent to the server.

Examples

# Assuming form contains a User schema
radio_button(form, :role, "admin")
#=> <input id="user_role_admin" name="user[role]" type="radio" value="admin">

Options

All options are simply forwarded to the underlying HTML tag.

Link to this function range_input(form, field, opts \\ []) View Source

Generates a range input.

See text_input/3 for example and docs.

Link to this function reset(value, opts \\ []) View Source

Generates a reset input to reset all the form fields to their original state.

All options are forwarded to the underlying input tag.

Examples

reset "Reset"
#=> <input type="reset" value="Reset">

reset "Reset", class: "btn"
#=> <input type="reset" value="Reset" class="btn">
Link to this function search_input(form, field, opts \\ []) View Source

Generates a search input.

See text_input/3 for example and docs.

Link to this function select(form, field, options, opts \\ []) View Source

Generates a select tag with the given options.

options are expected to be an enumerable which will be used to generate each respective option. The enumerable may have:

  • keyword lists - each keyword list is expected to have the keys :value and :label. Additional keys such as :disabled may be given to customize the option

  • two-item tuples - where the first element is an atom, string or integer to be used as the option label and the second element is an atom, string or integer to be used as the option value

  • atom, string or integer - which will be used as both label and value for the generated select

Optgroups

If options is map or keyword list where the first element is a string, atom or integer and the second element is a list or a map, it is assumed the key will be wrapped in an <optgroup> and the value will be used to generate <options> nested under the group.

Examples

# Assuming form contains a User schema
select(form, :age, 0..120)
#=> <select id="user_age" name="user[age]">
    <option value="0">0</option>
    ...
    <option value="120">120</option>
    </select>

select(form, :role, ["Admin": "admin", "User": "user"])
#=> <select id="user_role" name="user[role]">
    <option value="admin">Admin</option>
    <option value="user">User</option>
    </select>

select(form, :role, [[key: "Admin", value: "admin", disabled: true],
                     [key: "User", value: "user"])
#=> <select id="user_role" name="user[role]">
    <option value="admin" disabled="disabled">Admin</option>
    <option value="user">User</option>
    </select>

select(form, :role, ["Admin": "admin", "User": "user"], prompt: "Choose your role")
#=> <select id="user_role" name="user[role]">
    <option value="">Choose your role</option>
    <option value="admin">Admin</option>
    <option value="user">User</option>
    </select>

If you want to select an option that comes from the database, such as a manager for a given project, you may write:

select(form, :manager_id, Enum.map(@managers, &{&1.name, &1.id}))
#=> <select id="manager_id" name="project[manager_id]">
    <option value="1">Mary Jane</option>
    <option value="2">John Doe</option>
    </select>

Finally, if the values are a list or a map, we use the keys for grouping:

select(form, :country, ["Europe": ["UK", "Sweden", "France"]], ...})
#=> <select id="user_country" name="user[country]">
    <optgroup label="Europe">
      <option>UK</option>
      <option>Sweden</option>
      <option>France</option>
    </optgroup>
    ...
    </select>

Options

  • :prompt - an option to include at the top of the options with the given prompt text

  • :selected - the default value to use when none was sent as parameter

Be aware that a :multiple option will not generate a correctly functioning multiple select element. Use multiple_select/4 instead.

All other options are forwarded to the underlying HTML tag.

Generates a submit button to send the form.

All options are forwarded to the underlying button tag.

Examples

submit "Submit"
#=> <button type="submit">Submit</button>
Link to this function submit(opts, opts \\ []) View Source
Link to this function telephone_input(form, field, opts \\ []) View Source

Generates a telephone input.

See text_input/3 for example and docs.

Link to this function text_input(form, field, opts \\ []) View Source

Generates a text input.

The form should either be a Phoenix.HTML.Form emitted by form_for or an atom.

All given options are forwarded to the underlying input, default values are provided for id, name and value if possible.

Examples

# Assuming form contains a User schema
text_input(form, :name)
#=> <input id="user_name" name="user[name]" type="text" value="">

text_input(:user, :name)
#=> <input id="user_name" name="user[name]" type="text" value="">
Link to this function textarea(form, field, opts \\ []) View Source

Generates a textarea input.

All given options are forwarded to the underlying input, default values are provided for id, name and textarea content if possible.

Examples

# Assuming form contains a User schema
textarea(form, :description)
#=> <textarea id="user_description" name="user[description]"></textarea>

New lines

Notice the generated textarea includes a new line after the opening tag. This is because the HTML spec says new lines after tags must be ignored and all major browser implementations do that.

So in order to avoid new lines provided by the user from being ignored when the form is resubmitted, we automatically add a new line before the text area value.

Link to this function time_select(form, field, opts \\ []) View Source

Generates select tags for time.

Check datetime_select/3 for more information on options and supported values.

Link to this function url_input(form, field, opts \\ []) View Source

Generates an url input.

See text_input/3 for example and docs.