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$lock

Locks and unlocks an entity using the pessimistic mechanism.

Sintaxis

To lock an entity for other sessions and 4D processes:

/?$lock=true

To unlock the entity for other sessions and 4D processes:

/?$lock=false

The lockKindText property is "Locked by session".

Descripción

The locks triggered by the REST API are put at the session level.

A locked entity is seen as locked (i.e. lock / unlock / update / delete actions are not possible) by:

• otras sesiones REST
• 4D processes (client/server, remote datastore, standalone) running on the REST server.

An entity locked by the REST API can only be unlocked:

• by its locker, i.e. a /?$lock=false in the REST session that sets /?$lock=true
• or if the session's inactivity timeout is reached (the session is closed).

Respuesta

A ?$lock request returns a JSON object with "result"=true if the lock operation was successful and "result"=false if it failed.

The returned "__STATUS" object has the following properties:

| Propiedad | | Tipo | Descripción | | ------------ | | -------- | ----------------------------------------------------------------------------------------------------------------------------------------------- | | | | | Disponible sólo en caso de éxito: | | success | | booleano | true if the lock action is successful (or if the entity is already locked in the current session), false otherwise (not returned in this case). | | | | | Disponible sólo en caso de error: | | status | | number | Código de error, ver abajo | | statusText | | texto | Descripción del error, ver abajo | | lockKind | | number | Código de bloqueo | | lockKindText | | texto | "Locked by session" if locked by a REST session, "Locked by record" if locked by a 4D process |

The following values can be returned in the status and statusText properties of the __STATUS object in case of error:

status	statusText	Comentario
2	"Stamp has changed"	El valor del sello interno de la entidad no coincide con el de la entidad almacenada en los datos (bloqueo optimista).
3	"Already locked"	La entidad está bloqueada por un bloqueo pesimista.
4	"Other error"	Un error grave es un error de base de datos de bajo nivel (por ejemplo, una llave duplicada), un error de hardware, etc.
5	"Entity does not exist anymore"	La entidad ya no existe en los datos.

Ejemplo

Bloqueamos una entidad en un primer navegador:

GET /rest/Customers(1)/?$lock=true

Respuesta:

{
    "result": true,
    "__STATUS": {
        "success": true
    }
}

En un segundo navegador (otra sesión), enviamos la misma petición.

Respuesta:

{
    "result":false,
    "__STATUS":{
        "status":3,
        "statusText":"Already Locked",
        "lockKind":7,
        "lockKindText":"Locked By Session",
    }
}