FUNCTIONUnder review

EXISTCPO()

ExistCpo( alias, expressao, [indice] ) --> lRet

Validates reference existence.

EXISTCPO()AdvPL

01 · OVERVIEW

Overview

ExistCpo approves an existing reference and rejects a missing one. Supply the expression without branch as documented; do not automatically reuse a DBSeek key. Omitted index uses the last selected index according to this source. Rejection can display help, so this is not a generic silent lookup. The GitHub source demonstrates SA1 code/store calls; this proposal uses a parameterized callback without querying real records. Prevalidation alone does not solve concurrency or transactional uniqueness. (TOTVS, n.d., ref. 1)

02 · SYNTAX

Syntax

ExistCpo( alias, expressao, [indice] ) --> lRet

Parameters

alias

CharacterRequired

Validation alias.

expressao

CharacterRequired

Key without branch.

indice

NumericOptional

Order matching the expression.

Return value

True when its rule is satisfied; false on rejection.

03 · PRACTICAL EXAMPLE

Commented example

#Include "Protheus.ch"

User Function Ed374()
    Local bValidate := {|cAlias,cKey,nOrder| ExistCpo(cAlias,cKey,nOrder)}
    // Branch-free key and matching order; do not evaluate here.
Return Nil

Expected result

Block prepared without lookup; return meaning depends on each function’s rule. Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.

BEST PRACTICES

Confirm release-specific validation context, order and messages. Do not confuse the two logical meanings.
Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.