Xbase++ Requires Chilkat v11.7.0+
Box: Search Files with Offset Pagination

Run the reusable setup once per HttpCurl object, then select names and execute the operation. The setup is repeated here only to make this published example independently runnable. Search within a folder hierarchy. Box search is indexed and may lag recent changes; use returned upload IDs for immediate follow-up requests. Search uses offset pagination, not folder-list markers.
See the Box API guide for setup and the complete workflow.
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LOCAL nSuccess
LOCAL oCurl
LOCAL oSetupCommand
LOCAL nSetupReplacements
LOCAL cParentName
LOCAL cFolderName
LOCAL oPage
LOCAL oNumber
LOCAL nOffset
LOCAL nCount
LOCAL nPageLimit
LOCAL nTotal
LOCAL i
LOCAL nMore
LOCAL oAuthorizedCommand1
LOCAL nHeaderReplacement1

nSuccess := 0

//  Requires Chilkat 11.7.0 or later and a previously unlocked Chilkat bundle.
//  See Global Unlock Sample.
//  Guide: Box API Guide.

nSuccess := 0

//  BEGIN ONE-TIME SETUP
//  This block is repeated so each published example can run on its own.
//  In an application, run the setup example once and pass the SAME curl object
//  to operation code below. Do not recreate it for every operation.
//  See Reusable Box HttpCurl Setup.
oCurl := CreateObject("Chilkat.HttpCurl")
oCurl:SetVar("access_token", "BOX_ACCESS_TOKEN")
oCurl:SetVar("parent_name", "/")
//  Box's fixed root ID is an implementation detail; callers supply names.
oCurl:SetVar("parent_id", "0")
oSetupCommand := CreateObject("Chilkat.StringBuilder")

//  Register findParent; registration sends no request.
oSetupCommand:SetString('curl -X GET "https://api.box.com/2.0/folders/0/items?limit=1000&fields=id,type,name" -H "Authorization: Bearer ACCESS_TOKEN"')
nSetupReplacements := oSetupCommand:Replace("ACCESS_TOKEN", oCurl:GetVar("access_token"))
nSuccess := oCurl:AddFunction("findParent", oSetupCommand:GetAsString())
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

//  Register findFolder; registration sends no request.
oSetupCommand:SetString('curl -X GET "https://api.box.com/2.0/folders/{{parent_id}}/items?limit=1000&fields=id,type,name" -H "Authorization: Bearer ACCESS_TOKEN"')
nSetupReplacements := oSetupCommand:Replace("ACCESS_TOKEN", oCurl:GetVar("access_token"))
nSuccess := oCurl:AddFunction("findFolder", oSetupCommand:GetAsString())
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

//  Register findFile; registration sends no request.
oSetupCommand:SetString('curl -X GET "https://api.box.com/2.0/folders/{{folder_id}}/items?limit=1000&fields=id,type,name" -H "Authorization: Bearer ACCESS_TOKEN"')
nSetupReplacements := oSetupCommand:Replace("ACCESS_TOKEN", oCurl:GetVar("access_token"))
nSuccess := oCurl:AddFunction("findFile", oSetupCommand:GetAsString())
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

//  Register findDestination; registration sends no request.
oSetupCommand:SetString('curl -X GET "https://api.box.com/2.0/folders/0/items?limit=1000&fields=id,type,name" -H "Authorization: Bearer ACCESS_TOKEN"')
nSetupReplacements := oSetupCommand:Replace("ACCESS_TOKEN", oCurl:GetVar("access_token"))
nSuccess := oCurl:AddFunction("findDestination", oSetupCommand:GetAsString())
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

//  Register getFileDetails; registration sends no request.
oSetupCommand:SetString('curl -X GET "https://api.box.com/2.0/files/{{file_id}}?fields=id,sha1,file_version" -H "Authorization: Bearer ACCESS_TOKEN"')
nSetupReplacements := oSetupCommand:Replace("ACCESS_TOKEN", oCurl:GetVar("access_token"))
nSuccess := oCurl:AddFunction("getFileDetails", oSetupCommand:GetAsString())
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

//  Register getEnterprise; registration sends no request.
oSetupCommand:SetString('curl -X GET "https://api.box.com/2.0/users/me?fields=enterprise" -H "Authorization: Bearer ACCESS_TOKEN"')
nSetupReplacements := oSetupCommand:Replace("ACCESS_TOKEN", oCurl:GetVar("access_token"))
nSuccess := oCurl:AddFunction("getEnterprise", oSetupCommand:GetAsString())
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

//  Register output rules once. Chilkat 11.7.0 evaluates {{name}} variables
//  when extracting each output, using the current value at that time.
nSuccess := oCurl:AddOutput2("findParent", "entries", "name", "{{parent_name}}", 1, "id", "parent_id")
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

nSuccess := oCurl:AddOutput2("findFolder", "entries", "name", "{{folder_name}}", 1, "id", "folder_id")
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

nSuccess := oCurl:AddOutput2("findFile", "entries", "name", "{{file_name}}", 1, "id", "file_id")
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

nSuccess := oCurl:AddOutput2("findDestination", "entries", "name", "{{destination_name}}", 1, "id", "destination_id")
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

nSuccess := oCurl:AddOutput("getFileDetails", "file_version.id", "file_version_id")
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

nSuccess := oCurl:AddOutput("getFileDetails", "sha1", "file_sha1")
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

nSuccess := oCurl:AddOutput("getEnterprise", "enterprise.id", "enterprise_id")
IF (nSuccess != 1)
    ? oCurl:LastErrorText
    oCurl:destroy()
    oSetupCommand:destroy()
    RETURN
ENDIF

//  END ONE-TIME SETUP
//  The name lookups below assume each listing fits in one page (1000 items).
//  Parent and destination names select root children; folder_name selects a child
//  of parent_name. "/" selects the root parent. These are not arbitrary paths.

//  BEGIN OPERATION -- keep the configured object when reusing it.
//  Inputs are names. Retain cached IDs when the selected names have not changed.
cParentName := "/"
cFolderName := "images"
IF ((oCurl:GetVar("parent_name") != cParentName) .OR. ((cParentName == "/") .AND. (oCurl:VarDefined("parent_id") == 0)))
    oCurl:SetVar("parent_name", cParentName)
    oCurl:ClearVar("parent_id")
    oCurl:ClearVar("folder_id")
    oCurl:ClearVar("file_id")
    oCurl:ClearVar("file_version_id")
    oCurl:ClearVar("file_sha1")
    IF (cParentName == "/")
        oCurl:SetVar("parent_id", "0")
    ENDIF

ENDIF

IF (oCurl:GetVar("folder_name") != cFolderName)
    oCurl:SetVar("folder_name", cFolderName)
    oCurl:ClearVar("folder_id")
    oCurl:ClearVar("file_id")
    oCurl:ClearVar("file_version_id")
    oCurl:ClearVar("file_sha1")
ENDIF

oCurl:SetVar("query", "penguins")
oPage := CreateObject("Chilkat.JsonObject")
oNumber := CreateObject("Chilkat.StringBuilder")
nOffset := 0

nMore := 1
DO WHILE nMore == 1
    oNumber:Clear()
    oNumber:AppendInt(nOffset)
    oCurl:SetVar("offset", oNumber:GetAsString())
    oCurl:ClearTargetOutput("*")
    oAuthorizedCommand1 := CreateObject("Chilkat.StringBuilder")
    oAuthorizedCommand1:SetString('curl -X GET "https://api.box.com/2.0/search?query={{query}}&type=file&ancestor_folder_ids={{folder_id}}&content_types=name&limit=100&offset={{offset}}" -H "Authorization: Bearer {{access_token}}"')
    nHeaderReplacement1 := oAuthorizedCommand1:Replace("{{access_token}}", oCurl:GetVar("access_token"))
    nSuccess := oCurl:DoYourThing(oAuthorizedCommand1:GetAsString())
    IF ((nSuccess != 1) .OR. (oCurl:StatusCode != 200))
        ? "Box request failed. HTTP status: " + Str(oCurl:StatusCode)
        ? "Failure reason: " + Str(oCurl:FailReason)
        ? oCurl:ResponseBodyStr
        oCurl:destroy()
        oSetupCommand:destroy()
        oPage:destroy()
        oNumber:destroy()
        oAuthorizedCommand1:destroy()
        RETURN
    ENDIF

    nSuccess := oCurl:GetResponseJson(oPage)
    IF (nSuccess != 1)
        ? oCurl:LastErrorText
        oCurl:destroy()
        oSetupCommand:destroy()
        oPage:destroy()
        oNumber:destroy()
        oAuthorizedCommand1:destroy()
        RETURN
    ENDIF

    nCount := oPage:SizeOfArray("entries")
    i := 0
    DO WHILE i < nCount
        oPage:I := i
        ? oPage:StringOf("entries[i].id") + " " + oPage:StringOf("entries[i].name")
        i := i + 1
    ENDDO
    nPageLimit := oPage:IntOf("limit")
    nTotal := oPage:IntOf("total_count")
    IF (nPageLimit <= 0)
        ? "Missing or invalid search page limit."
        oCurl:destroy()
        oSetupCommand:destroy()
        oPage:destroy()
        oNumber:destroy()
        oAuthorizedCommand1:destroy()
        RETURN
    ENDIF

    nOffset := nOffset + nPageLimit
    nMore := (nOffset < nTotal) .AND. (nCount > 0)
    IF ((nMore == 1) .AND. (nOffset > 9999))
        ? "Search offset limit reached; narrow the query or folder scope."
        oCurl:destroy()
        oSetupCommand:destroy()
        oPage:destroy()
        oNumber:destroy()
        oAuthorizedCommand1:destroy()
        RETURN
    ENDIF

ENDDO

oCurl:destroy()
oSetupCommand:destroy()
oPage:destroy()
oNumber:destroy()
oAuthorizedCommand1:destroy()