A successful control must be defined within a FORM element and must have a control name. If a control doesn't have a current value when the form is submitted, user agents are not required to treat it as a successful control. Hidden controls and controls that are not rendered because of style sheet settings may still be successful. For example:. will still cause a value to be paired with the name "invisible-password" and submitted with the form.

When the user submits a form e. The form data set is then encoded according to the content type specified by the enctype attribute of the FORM element. Finally, the encoded data is sent to the processing agent designated by the action attribute using the protocol specified by the method attribute.

This specification does not specify all valid submission methods or content types that may be used with forms. However, HTML 4 user agents must support the established conventions in the following cases:. For any other value of action or method , behavior is unspecified. The enctype attribute of the FORM element specifies the content type used to encode the form data set for submission to the server.

User agents must support the content types listed below. Behavior for other content types is unspecified. Please also consult the section on escaping ampersands in URI attribute values. This is the default content type. Forms submitted with this content type must be encoded as follows:. Please consult the appendix for information about security issues for forms. The parts are sent to the processing agent in the same order the corresponding controls appear in the document stream.

Part boundaries should not occur in any of the data; how this is done lies outside the scope of this specification. User agents should supply the "Content-Type" header, accompanied by a "charset" parameter. As with all MIME transmissions, "CR LF" i. Each part may be encoded and the "Content-Transfer-Encoding" header supplied if the value of that part does not conform to the default 7BIT encoding see [RFC] , section 6.

If the contents of a file are submitted with a form, the file input should be identified by the appropriate content type e. The user agent should attempt to supply a file name for each submitted file. The file name may be specified with the "filename" parameter of the 'Content-Disposition: form-data' header, or, in the case of multiple files, in a 'Content-Disposition: file' header of the subpart.

If the file name of the client's operating system is not in US-ASCII, the file name might be approximated or encoded using the method of [RFC]. This is convenient for those cases where, for example, the uploaded files might contain references to each other e. sty" auxiliary style description.

Suppose we have the following form:. If the user enters "Larry" in the text input, and selects the text file "file1. txt", the user agent might send back the following data:. If the user selected a second image file "file2. gif", the user agent might construct the parts as follows:. previous next contents elements attributes index. User agent behavior for a value other than an HTTP URI is undefined. Possible case-insensitive values are "get" the default and "post". See the section on form submission for usage information.

The client must interpret this list as an exclusive-or list, i. User agents may use this information to filter out non-conforming files when prompting a user to select files to be sent to the server cf. This attribute has been included for backwards compatibility. Applications should use the id attribute to identify elements. Attributes defined elsewhere id , class document-wide identifiers lang language information , dir text direction style inline style information title element title target target frame information onsubmit , onreset , onclick , ondblclick , onmousedown , onmouseup , onmouseover , onmousemove , onmouseout , onkeypress , onkeydown , onkeyup intrinsic events.

form contents The default value for this attribute is "text". It is optional except when the type attribute has the value "radio" or "checkbox". The width is given in pixels except when type attribute has the value "text" or "password".

In that case, its value refers to the integer number of characters. This number may exceed the specified size , in which case the user agent should offer a scrolling mechanism. The default value for this attribute is an unlimited number. checked [CI] When the type attribute has the value "radio" or "checkbox", this boolean attribute specifies that the button is on.

User agents must ignore this attribute for other control types. Attributes defined elsewhere id , class document-wide identifiers lang language information , dir text direction title element title style inline style information alt alternate text align alignment accept legal content types for a server readonly read-only input controls disabled disabled input controls tabindex tabbing navigation accesskey access keys usemap client-side image maps ismap server-side image maps onfocus , onblur , onselect , onchange , onclick , ondblclick , onmousedown , onmouseup , onmouseover , onmousemove , onmouseout , onkeypress , onkeydown , onkeyup intrinsic events.

Possible values: submit: Creates a submit button. This is the default value. reset: Creates a reset button. button: Creates a push button. Attributes defined elsewhere id , class document-wide identifiers lang language information , dir text direction title element title style inline style information disabled disabled input controls accesskey access keys tabindex tabbing navigation onfocus , onblur , onclick , ondblclick , onmousedown , onmouseup , onmouseover , onmousemove , onmouseout , onkeypress , onkeydown , onkeyup intrinsic events.

ILLEGAL EXAMPLE: The following is not legal HTML. Visual user agents are not required to present a SELECT element as a list box; they may use any other mechanism, such as a drop-down menu. multiple [CI] If set, this boolean attribute allows multiple selections. If not set, the SELECT element only permits single selections. Attributes defined elsewhere id , class document-wide identifiers lang language information , dir text direction title element title style inline style information disabled disabled input controls tabindex tabbing navigation onclick , ondblclick , onmousedown , onmouseup , onmouseover , onmousemove , onmouseout , onkeypress , onkeydown , onkeyup intrinsic events.

Attributes defined elsewhere id , class document-wide identifiers lang language information , dir text direction title element title style inline style information disabled disabled input controls onclick , ondblclick , onmousedown , onmouseup , onmouseover , onmousemove , onmouseout , onkeypress , onkeydown , onkeyup intrinsic events. OPTION Attribute definitions selected [CI] When set, this boolean attribute specifies that this option is pre-selected.

If this attribute is not set, the initial value is set to the contents of the OPTION element. When specified, user agents should use the value of this attribute rather than the content of the OPTION element as the option label. A graphical user agent might render this as: This image shows a SELECT element rendered as cascading menus. Users should be able to enter more lines than this, so user agents should provide some means to scroll through the contents of the control when the contents extend beyond the visible area.

Users should be able to enter longer lines than this, so user agents should provide some means to scroll through the contents of the control when the contents extend beyond the visible area.

User agents may wrap visible text lines to keep long lines visible without the need for scrolling. Attributes defined elsewhere id , class document-wide identifiers lang language information , dir text direction title element title style inline style information readonly read-only input controls disabled disabled input controls tabindex tabbing navigation onfocus , onblur , onselect , onchange , onclick , ondblclick , onmousedown , onmouseup , onmouseover , onmousemove , onmouseout , onkeypress , onkeydown , onkeyup intrinsic events.

Second line of initial text. This attribute specifies a prompt string for the input field. Attributes defined elsewhere id , class document-wide identifiers lang language information , dir text direction title element title style inline style information. When present, the value of this attribute must be the same as the value of the id attribute of some other control in the same document.

When absent, the label being defined is associated with the element's contents. Attributes defined elsewhere id , class document-wide identifiers lang language information , dir text direction title element title style inline style information accesskey access keys onfocus , onblur , onclick , ondblclick , onmousedown , onmouseup , onmouseover , onmousemove , onmouseout , onkeypress , onkeydown , onkeyup intrinsic events. This attribute specifies the position of the legend with respect to the fieldset.

Possible values: top: The legend is at the top of the fieldset. bottom: The legend is at the bottom of the fieldset. left: The legend is at the left side of the fieldset.

right: The legend is at the right side of the fieldset. Attributes defined elsewhere id , class document-wide identifiers lang language information , dir text direction title element title style inline style information accesskey access keys onclick , ondblclick , onmousedown , onmouseup , onmouseover , onmousemove , onmouseout , onkeypress , onkeydown , onkeyup intrinsic events.

more personal information more medical history This value must be a number between 0 and User agents should ignore leading zeros. some text some more An access key is a single character from the document character set.

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Why Mac Incredible power. Behaves like the standard Python file. close method and closes the file associated with this instance. This method takes a filename and file contents and passes them to the storage class for the field, then associates the stored file with the model field. If you want to manually associate file data with FileField instances on your model, the save method is used to persist that file data. The optional save argument controls whether or not the model instance is saved after the file associated with this field has been altered.

Defaults to True. Note that the content argument should be an instance of django. You can construct a File from an existing Python file object like this:. For more information, see Managing files. Deletes the file associated with this instance and clears all attributes on the field. Note: This method will close the file if it happens to be open when delete is called. The optional save argument controls whether or not the model instance is saved after the file associated with this field has been deleted.

Note that when a model is deleted, related files are not deleted. A CharField whose choices are limited to the filenames in a certain directory on the filesystem.

Has some special arguments, of which the first is required :. The absolute filesystem path to a directory from which this FilePathField should get its choices. path may also be a callable, such as a function to dynamically set the path at runtime. A regular expression, as a string, that FilePathField will use to filter filenames.

Note that the regex will be applied to the base filename, not the full path. Example: "foo. txt but not bar. txt or foo Either True or False. Specifies whether all subdirectories of path should be included. Specifies whether files in the specified location should be included. Specifies whether folders in the specified location should be included.

The one potential gotcha is that match applies to the base filename, not the full path. So, this example:. png because the match applies to the base filename foo. png and bar. FilePathField instances are created in your database as varchar columns with a default max length of characters. A floating-point number represented in Python by a float instance. FloatField vs. The FloatField class is sometimes mixed up with the DecimalField class.

Although they both represent real numbers, they represent those numbers differently. An IPv4 or IPv6 address, in string format e. The IPv6 address normalization follows RFC section For example, would be normalized to , and ::ffff:0a0a:0a0a to ::ffff All characters are converted to lowercase.

Limits valid inputs to the specified protocol. Accepted values are 'both' default , 'IPv4' or 'IPv6'. Matching is case insensitive. Unpacks IPv4 mapped addresses like ::ffff If this option is enabled that address would be unpacked to Default is disabled.

Can only be used when protocol is set to 'both'. If you allow for blank values, you have to allow for null values since blank values are stored as null. Inherits all attributes and methods from FileField , but also validates that the uploaded object is a valid image.

In addition to the special attributes that are available for FileField , an ImageField also has height and width attributes. To facilitate querying on those attributes, ImageField has the following optional arguments:. Name of a model field which will be auto-populated with the height of the image each time the model instance is saved. Name of a model field which will be auto-populated with the width of the image each time the model instance is saved.

Requires the Pillow library. ImageField instances are created in your database as varchar columns with a default max length of characters. An integer. Values from to are safe in all databases supported by Django.

It uses MinValueValidator and MaxValueValidator to validate the input based on the values that the default database supports. A field for storing JSON encoded data. In Python the data is represented in its Python native format: dictionaries, lists, strings, numbers, booleans and None. JSONField is supported on MariaDB, MySQL 5.

An optional json. JSONEncoder subclass to serialize data types not supported by the standard JSON serializer e. datetime or UUID. For example, you can use the DjangoJSONEncoder class. Defaults to json.

JSONDecoder subclass to deserialize the value retrieved from the database. The value will be in the format chosen by the custom encoder most often a string. For example, you run the risk of returning a datetime that was actually a string that just happened to be in the same format chosen for datetime s.

To query JSONField in the database, see Querying JSONField. Index and Field. On PostgreSQL only, you can use GinIndex that is better suited. PostgreSQL has two native JSON based data types: json and jsonb. The main difference between them is how they are stored and how they can be queried.

The jsonb field is stored based on the actual structure of the JSON which allows indexing. The trade-off is a small additional cost on writing to the jsonb field. JSONField uses jsonb. Oracle Database does not support storing JSON scalar values. Only JSON objects and arrays represented in Python using dict and list are supported. Like a PositiveIntegerField , but only allows values under a certain database-dependent point.

Values from 0 to are safe in all databases supported by Django. Like an IntegerField , but must be either positive or zero 0. The value 0 is accepted for backward compatibility reasons. Slug is a newspaper term. A slug is a short label for something, containing only letters, numbers, underscores or hyphens. Implies setting Field. It is often useful to automatically prepopulate a SlugField based on the value of some other value. If True , the field accepts Unicode letters in addition to ASCII letters.

Defaults to False. Like an AutoField , but only allows values under a certain database-dependent limit. Values from 1 to are safe in all databases supported by Django. Like an IntegerField , but only allows values under a certain database-dependent point. A large text field. The default form widget for this field is a Textarea. However it is not enforced at the model or database level.

Use a CharField for that. Oracle does not support collations for a TextField. A time, represented in Python by a datetime. time instance. Accepts the same auto-population options as DateField. The default form widget for this field is a TimeInput. The admin adds some JavaScript shortcuts. A CharField for a URL, validated by URLValidator.

The default form widget for this field is a URLInput. A field for storing universally unique identifiers. When used on PostgreSQL, this stores in a uuid datatype, otherwise in a char The database will not generate the UUID for you, so it is recommended to use default :. Note that a callable with the parentheses omitted is passed to default , not an instance of UUID. A many-to-one relationship. To create a recursive relationship — an object that has a many-to-one relationship with itself — use models.

If you need to create a relationship on a model that has not yet been defined, you can use the name of the model, rather than the model object itself:. To refer to models defined in another application, you can explicitly specify a model with the full application label. This sort of reference, called a lazy relationship, can be useful when resolving circular import dependencies between two applications. A database index is automatically created on the ForeignKey.

You may want to avoid the overhead of an index if you are creating a foreign key for consistency rather than joins, or if you will be creating an alternative index like a partial or multiple column index.

ForeignKey accepts other arguments that define the details of how the relation works. For example, if you have a nullable ForeignKey and you want it to be set null when the referenced object is deleted:. Support for database-level cascade options may be implemented later. models :. Cascade deletes. Django emulates the behavior of the SQL constraint ON DELETE CASCADE and also deletes the object containing the ForeignKey.

Prevent deletion of the referenced object by raising ProtectedError , a subclass of django. Prevent deletion of the referenced object by raising RestrictedError a subclass of django. Unlike PROTECT , deletion of the referenced object is allowed if it also references a different object that is being deleted in the same operation, but via a CASCADE relationship.

Artist can be deleted even if that implies deleting an Album which is referenced by a Song , because Song also references Artist itself through a cascading relationship. Set the ForeignKey null; this is only possible if null is True.

Set the ForeignKey to its default value; a default for the ForeignKey must be set. Set the ForeignKey to the value passed to SET , or if a callable is passed in, the result of calling it. In most cases, passing a callable will be necessary to avoid executing queries at the time your models. py is imported:.

Take no action. If your database backend enforces referential integrity, this will cause an IntegrityError unless you manually add an SQL ON DELETE constraint to the database field. Sets a limit to the available choices for this field when this field is rendered using a ModelForm or the admin by default, all objects in the queryset are available to choose.

Either a dictionary, a Q object, or a callable returning a dictionary or Q object can be used. This may be helpful in the Django admin. The callable form can be helpful, for instance, when used in conjunction with the Python datetime module to limit selections by date range.

It may also be invoked when a model is validated, for example by management commands or the admin. The admin constructs querysets to validate its form inputs in various edge cases multiple times, so there is a possibility your callable may be invoked several times. The name to use for the relation from the related object back to this one. See the related objects documentation for a full explanation and example. Note that you must set this value when defining relations on abstract models ; and when you do so some special syntax is available.

The name to use for the reverse filter name from the target model. The field on the related object that the relation is to. By default, Django uses the primary key of the related object.

Controls whether or not a constraint should be created in the database for this foreign key. That said, here are some scenarios where you might want to do this:. If it is True - the default - then if the ForeignKey is pointing at a model which matches the current value of settings.

You only want to override this to be False if you are sure your model should always point toward the swapped-in model - for example, if it is a profile model designed specifically for your custom user model.

If in doubt, leave it to its default of True. A many-to-many relationship. Requires a positional argument: the class to which the model is related, which works exactly the same as it does for ForeignKey , including recursive and lazy relationships.

Behind the scenes, Django creates an intermediary join table to represent the many-to-many relationship. By default, this table name is generated using the name of the many-to-many field and the name of the table for the model that contains it. ManyToManyField accepts an extra set of arguments — all optional — that control how the relationship functions. Same as ForeignKey. Instead, the ManyToManyField is assumed to be symmetrical — that is, if I am your friend, then you are my friend.

If you do not want symmetry in many-to-many relationships with self , set symmetrical to False. This will force Django to add the descriptor for the reverse relationship, allowing ManyToManyField relationships to be non-symmetrical. Django will automatically generate a table to manage many-to-many relationships. However, if you want to manually specify the intermediary table, you can use the through option to specify the Django model that represents the intermediate table that you want to use.

The most common use for this option is when you want to associate extra data with a many-to-many relationship. It has three fields to link the models. If the ManyToManyField points from and to the same model, the following fields are generated:.

This class can be used to query associated records for a given model instance like a normal model:. Only used when a custom intermediary model is specified. Django will normally determine which fields of the intermediary model to use in order to establish a many-to-many relationship automatically.

However, consider the following models:. This also applies to recursive relationships when an intermediary model is used and there are more than two foreign keys to the model, or you want to explicitly specify which two Django should use. The name of the table to create for storing the many-to-many data.

If this is not provided, Django will assume a default name based upon the names of: the table for the model defining the relationship and the name of the field itself. Controls whether or not constraints should be created in the database for the foreign keys in the intermediary table. If it is True - the default - then if the ManyToManyField is pointing at a model which matches the current value of settings.

ManyToManyField does not support validators. null has no effect since there is no way to require a relationship at the database level. A one-to-one relationship.

One positional argument is required: the class to which the model will be related. This works exactly the same as it does for ForeignKey , including all the options regarding recursive and lazy relationships. your resulting User model will have the following attributes:.

The BINARY and VARBINARY types are similar to CHAR and VARCHAR , except that they store binary strings rather than nonbinary strings. That is, they store byte strings rather than character strings. This means they have the binary character set and collation, and comparison and sorting are based on the numeric values of the bytes in the values.

The permissible maximum length is the same for BINARY and VARBINARY as it is for CHAR and VARCHAR , except that the length for BINARY and VARBINARY is measured in bytes rather than characters.

The BINARY and VARBINARY data types are distinct from the CHAR BINARY and VARCHAR BINARY data types. For the latter types, the BINARY attribute does not cause the column to be treated as a binary string column.

This differs from BINARY 5 , which stores 5-byte binary strings that have the binary character set and collation. If strict SQL mode is not enabled and you assign a value to a BINARY or VARBINARY column that exceeds the column's maximum length, the value is truncated to fit and a warning is generated.

For cases of truncation, to cause an error to occur rather than a warning and suppress insertion of the value, use strict SQL mode. See Section 5. When BINARY values are stored, they are right-padded with the pad value to the specified length.

The pad value is 0x00 the zero byte. Values are right-padded with 0x00 for inserts, and no trailing bytes are removed for retrievals. All bytes are significant in comparisons, including ORDER BY and DISTINCT operations. Both inserted values remain unchanged for retrievals. For VARBINARY , there is no padding for inserts and no bytes are stripped for retrievals. For those cases where trailing pad bytes are stripped or comparisons ignore them, if a column has an index that requires unique values, inserting values into the column that differ only in number of trailing pad bytes results in a duplicate-key error.

You should consider the preceding padding and stripping characteristics carefully if you plan to use the BINARY data type for storing binary data and you require that the value retrieved be exactly the same as the value stored. The following example illustrates how 0x00 -padding of BINARY values affects column value comparisons:. If the value retrieved must be the same as the value specified for storage with no padding, it might be preferable to use VARBINARY or one of the BLOB data types instead.

Within the mysql client, binary strings display using hexadecimal notation, depending on the value of the --binary-as-hex. For more information about that option, see Section 4. Documentation Home MySQL 8. MySQL Server Administration. Integer Types Exact Value - INTEGER, INT, SMALLINT, TINYINT, MEDIUMINT, BIGINT. Fixed-Point Types Exact Value - DECIMAL, NUMERIC. Floating-Point Types Approximate Value - FLOAT, DOUBLE. Numeric Type Attributes.

Out-of-Range and Overflow Handling. Date and Time Data Type Syntax. The DATE, DATETIME, and TIMESTAMP Types. Automatic Initialization and Updating for TIMESTAMP and DATETIME.

Fractional Seconds in Time Values. Conversion Between Date and Time Types. The BINARY and VARBINARY Types. The OpenGIS Geometry Model. The Geometry Class Hierarchy. GeometryCollection Class. MultiLineString Class. Supported Spatial Data Formats. Geometry Well-Formedness and Validity. Spatial Reference System Support. Creating Spatial Columns. Populating Spatial Columns. Optimizing Spatial Analysis. Creating Spatial Indexes. Data Type Storage Requirements.

Choosing the Right Type for a Column. Using Data Types from Other Database Engines. The InnoDB Storage Engine. Using MySQL as a Document Store. InnoDB Cluster. InnoDB ReplicaSet. MySQL on the OCI Marketplace. Error Messages and Common Problems. MySQL 8. PDF US Ltr - version 8.

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Credit card issuers will be informed of the fraudulent nature of much of the industry, which could possibly allow victims to receive a chargeback , or refund, of fraudulently obtained money. The width is given in pixels except when type attribute has the value "text" or "password". Note A new migration is created each time the order of choices changes. The only way to modify dynamically the value of the disabled attribute is through a script. proto files by importing them. PostgreSQL has two native JSON based data types: json and jsonb. In this example, we create a menu that allows the user to select which of seven software components to install.

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