table-columns.md

Table columns

Entity consist of columns. For each entity column, column in the database will be created.

• @Column decorator
• @PrimaryColumn decorator
• @CreateDateColumn decorator
• @UpdateDateColumn decorator
• Column types
• Column options
• Columns usage example

@Column

Column decorator simply marks an entity property to be a table column. There are several column decorator signatures:

@Column(options?: ColumnOptions)
@Column(type?: ColumnType, options?: ColumnOptions)

@PrimaryColumn

PrimaryColumn marks an entity property as a column and creates a primary key for it. There are several column decorator signatures:

@PrimaryColumn(options?: ColumnOptions)
@PrimaryColumn(type?: ColumnType, options?: ColumnOptions)

@CreateDateColumn

CreateDateColumn adds a simple datetime column to the table. During its first persistence (e.g. insertion) it sets current date as a value of the property object.

@CreateDateColumn(options?: ColumnOptions)

@UpdateDateColumn

UpdateDateColumn adds a simple datetime column to the table. Each time object is persisted, this column value is updated to the current date.

@CreateDateColumn(options?: ColumnOptions)

ColumnType

ColumnType can be one of:

• string will be mapped to db's varchar
• text will be mapped to db's text
• number will be mapped to db's double
• integer will be mapped to db's int
• int will be mapped to db's int
• smallint will be mapped to db's int
• bigint will be mapped to db's int
• float will be mapped to db's float
• double will be mapped to db's double
• decimal will be mapped to db's decimal
• date will be mapped to db's datetime
• time will be mapped to db's time
• datetime will be mapped to db's datetime
• timestamp will be mapped to db's timestamp
• boolean will be mapped to db's boolean
• json will be mapped to db's text
• simple_array will be mapped to db's text

If you omit a column type, type will be guessed automatically based on variable type:

• number will be mapped to float
• boolean will be mapped to boolean
• string will be mapped to varchar
• Date will be mapped to datetime

ColumnOptions

ColumnOptions is an object with additional column options:

• name?: string - column name in the database
• type?: ColumnType - column type also can be specified via column options
• length?: string - column type's length. For example type = "string" and length = 100 means that ORM will create a column with type varchar(100).
• generated?: boolean - specifies if this column will use AUTO_INCREMENT or not (e.g. generated number)
• unique?: boolean - specifies if column's value must be unique or not.
• nullable?: boolean - indicates if column's value can be set to NULL.
• columnDefinition?: string - Extra column definition. Should be used only in emergency situations. Note that if you'll use this property auto schema generation will not work properly anymore.
• comment?: string - column comment
• precision?: number - The precision for a decimal (exact numeric) column (applies only for decimal column), which is the maximum number of digits that are stored for the values.
• scale?: number - The scale for a decimal (exact numeric) column (applies only for decimal column), which represents the number of digits to the right of the decimal point and must not be greater than precision.
• collation?: string - Column collation. Note that not all databases support it.

Example

@Table("photo")
class Photo {

    /**
     * Primary column with auto increment key.
     */
    @PrimaryColumn("int", { generated: true })
    id: number;

    /**
     * Simple string column.
     */
    @Column()
    name: string;

    /**
     * Simple boolean column.
     */
    @Column()
    isPublished: boolean;

    /**
     * Simple numeric (float) column.
     */
    @Column()
    scale: number;

    /**
     * Simple numeric (integer) column.
     */
    @Column("integer")
    size: number;

    /**
     * Simple column that contains a date.
     */
    @Column()
    publishedDate: Date;

    /**
     * Simple column that contains a big text.
     */
    @Column("text")
    description: string;

    /**
     * Simple column that contains a short text.
     */
    @Column({
        length: 3
    })
    locale: string;

    /**
     * This column's value must be unique.
     */
    @Column({
        unique: true
    })
    slug: string;

    /**
     * This column's value can be nullable.
     */
    @Column({
        nullable: true
    })
    metadata: string;
    
}