JS: Attributes - Yuneta Simplified

Attributes¶

A gclass declares its attributes in a table. Each attribute has a type, a name, a set of flags, a default value and a description.

Source code: src/gobj.js

import { SDATA, SDATA_END, data_type_t, sdata_flag_t } from "@yuneta/gobj-js";

const attrs_table = [
    SDATA(data_type_t.DTP_STRING,  "url",       sdata_flag_t.SDF_RD,      "", "Server URL"),
    SDATA(data_type_t.DTP_INTEGER, "timeout",   sdata_flag_t.SDF_RD,       0, "Timeout ms"),
    SDATA(data_type_t.DTP_BOOLEAN, "connected", sdata_flag_t.SDF_RD,   false, "Connection state"),
    SDATA(data_type_t.DTP_STRING,  "saved_key", sdata_flag_t.SDF_PERSIST, "", "Persisted value"),
    SDATA_END()
];

Declare¶

`SDATA(type, name, flag, default_value, description)`¶

Declares one attribute. The table finishes with SDATA_END().

`data_type_t`¶

The types of an attribute.

Type	Description
`DTP_STRING`	A string.
`DTP_BOOLEAN`	A boolean.
`DTP_INTEGER`	An integer.
`DTP_REAL`	A real number.
`DTP_LIST`	A list.
`DTP_DICT`	An object.
`DTP_JSON`	Any JSON value.
`DTP_POINTER`	A value that is not JSON, such as a gobj or a DOM node.

`sdata_flag_t`¶

The flags of an attribute. Combine them with the bit-or operator.

Flag	Description
`SDF_NOTACCESS`	Not reachable from outside.
`SDF_RD`	A reader can read it.
`SDF_WR`	A writer can write it.
`SDF_REQUIRED`	The creation must give a value.
`SDF_PERSIST`	The framework saves it and loads it again.
`SDF_VOLATIL`	`gobj_reset_volatil_attrs()` clears it.
`SDF_RESOURCE`	A resource.
`SDF_PKEY`	The primary key of a record.
`SDF_DEPRECATED`	Kept for the old callers.
`SDF_WILD_CMD`	A command that accepts a free form.
`SDF_STATS`	A statistic.
`SDF_FKEY`	A foreign key of a record.
`SDF_RSTATS`	A statistic that resets when a reader reads it.
`SDF_PSTATS`	A statistic that persists.
`SDF_AUTHZ_R`	The read needs an authorization.
`SDF_AUTHZ_W`	The write needs an authorization.
`SDF_AUTHZ_X`	The execution needs an authorization.
`SDF_AUTHZ_P`	The subscription needs an authorization.
`SDF_AUTHZ_S`	The statistics need an authorization.
`SDF_AUTHZ_RS`	The reset of the statistics needs an authorization.

Read¶

`gobj_has_attr(gobj, name)`¶

Tells if a gobj has an attribute with that name.

`gobj_read_attr(gobj, name, src)`¶

Reads an attribute of any type. src names the gobj that asks, for the authorization and for the log.

`gobj_read_attrs(gobj, include_flag, src)`¶

Reads every attribute whose flags match include_flag, as one object.

`gobj_read_bool_attr(gobj, name)`¶

Reads a boolean attribute.

`gobj_read_integer_attr(gobj, name)`¶

Reads an integer attribute.

`gobj_read_str_attr(gobj, name)`¶

Reads a string attribute.

`gobj_read_pointer_attr(gobj, name)`¶

Reads an attribute that holds a value which is not JSON. The subscriber attribute of the subscription model uses it.

`gobj_hsdata(gobj)`¶

Gives the whole store of the attributes of a gobj. It is an internal handle, and the functions above are the way to read an attribute.

Write¶

`gobj_write_attr(gobj, path, value, src)`¶

Writes an attribute of any type.

`gobj_write_attrs(gobj, kw, include_flag, src)`¶

Writes every attribute of kw whose flags match include_flag.

`gobj_write_bool_attr(gobj, name, value)`¶

Writes a boolean attribute.

`gobj_write_integer_attr(gobj, name, value)`¶

Writes an integer attribute.

`gobj_write_str_attr(gobj, name, value)`¶

Writes a string attribute.

`gobj_reset_volatil_attrs(gobj)`¶

Writes the default value in every attribute that carries SDF_VOLATIL.

An attribute with SDF_PERSIST goes to the store through the callbacks that gobj_start_up() receives. See Persistence.