(PureBasic) Get Object MetaData from Google Cloud Storage

Demonstrates how to download a Google Cloud Storage object's metadata.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkStringBuilder.pb"
IncludeFile "CkHttp.pb"

Procedure ChilkatExample()

    ; This example requires the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

    ; This example uses a previously obtained access token having permission for the 
    ; scope "https://www.googleapis.com/auth/cloud-platform"

    ; In this example, Get Google Cloud Storage OAuth2 Access Token, 
    ; the service account access token was saved to a text file.  This example fetches the access token from the file..
    sbToken.i = CkStringBuilder::ckCreate()
    If sbToken.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckLoadFile(sbToken,"qa_data/tokens/googleCloudStorageAccessToken.txt","utf-8")

    ; Send a GET equivalent to this curl command.

    ; curl -X GET \
    ;     -H "Authorization: Bearer [OAUTH2_TOKEN]" \
    ;     -o "[SAVE_TO_LOCATION]" \
    ;     "https://www.googleapis.com/storage/v1/b/[BUCKET_NAME]/o/[OBJECT_NAME]?projection=full"

    http.i = CkHttp::ckCreate()
    If http.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkHttp::setCkAuthToken(http, CkStringBuilder::ckGetAsString(sbToken))

    ; Construct a URL to download the metadata for the object named "starfish.jpg" located in the "chilkat-ocean" bucket.
    CkHttp::ckSetUrlVar(http,"bucket_name","chilkat-ocean")
    CkHttp::ckSetUrlVar(http,"object_name","starfish.jpg")
    url.s = "https://www.googleapis.com/storage/v1/b/{$bucket_name}/o/{$object_name}?projection=full"

    ; If there is an error response, then we didn't actually download the metadata,
    ; but instead we downloaded an error response..
    sbMetaData.i = CkStringBuilder::ckCreate()
    If sbMetaData.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success.i = CkHttp::ckDownloadSb(http,url,"utf-8",sbMetaData)
    If success = 0
        Debug CkHttp::ckLastErrorText(http)
        CkStringBuilder::ckDispose(sbToken)
        CkHttp::ckDispose(http)
        CkStringBuilder::ckDispose(sbMetaData)
        ProcedureReturn
    EndIf

    responseCode.i = CkHttp::ckLastStatus(http)
    If responseCode = 401
        Debug "If invalid credentials, then it is likely the access token expired."
        Debug "Your app should automatically fetch a new access token and re-try."
    EndIf

    If responseCode <> 200
        Debug "Error response code = " + Str(responseCode)
        Debug "Error:"
        Debug CkStringBuilder::ckGetAsString(sbMetaData)
        CkStringBuilder::ckDispose(sbToken)
        CkHttp::ckDispose(http)
        CkStringBuilder::ckDispose(sbMetaData)
        ProcedureReturn
    EndIf

    Debug CkStringBuilder::ckGetAsString(sbMetaData)
    Debug "Success."

    ; Sample output:

    ; {
    ;  "kind": "storage#object",
    ;  "id": "chilkat-ocean/starfish.jpg/1502670320090292",
    ;  "selfLink": "https://www.googleapis.com/storage/v1/b/chilkat-ocean/o/starfish.jpg",
    ;  "name": "starfish.jpg",
    ;  "bucket": "chilkat-ocean",
    ;  "generation": "1502670320090292",
    ;  "metageneration": "1",
    ;  "contentType": "image/jpeg",
    ;  "timeCreated": "2017-08-14T00:25:20.040Z",
    ;  "updated": "2017-08-14T00:25:20.040Z",
    ;  "storageClass": "MULTI_REGIONAL",
    ;  "timeStorageClassUpdated": "2017-08-14T00:25:20.040Z",
    ;  "size": "6229",
    ;  "md5Hash": "LpxZ2/JmI2fcl9/dqF2gSA==",
    ;  "mediaLink": "https://www.googleapis.com/download/storage/v1/b/chilkat-ocean/o/starfish.jpg?generation=1502670320090292&alt=media",
    ;  "acl": [
    ;   {
    ;    "kind": "storage#objectAccessControl",
    ;    "id": "chilkat-ocean/starfish.jpg/1502670320090292/project-owners-933037264567",
    ;    "selfLink": "https://www.googleapis.com/storage/v1/b/chilkat-ocean/o/starfish.jpg/acl/project-owners-933037264567",
    ;    "bucket": "chilkat-ocean",
    ;    "object": "starfish.jpg",
    ;    "generation": "1502670320090292",
    ;    "entity": "project-owners-933037264567",
    ;    "role": "OWNER",
    ;    "projectTeam": {
    ;     "projectNumber": "933037264567",
    ;     "team": "owners"
    ;    },
    ;    "etag": "CLT5kpW71dUCEAE="
    ;   },
    ;   {
    ;    "kind": "storage#objectAccessControl",
    ;    "id": "chilkat-ocean/starfish.jpg/1502670320090292/project-editors-933037264567",
    ;    "selfLink": "https://www.googleapis.com/storage/v1/b/chilkat-ocean/o/starfish.jpg/acl/project-editors-933037264567",
    ;    "bucket": "chilkat-ocean",
    ;    "object": "starfish.jpg",
    ;    "generation": "1502670320090292",
    ;    "entity": "project-editors-933037264567",
    ;    "role": "OWNER",
    ;    "projectTeam": {
    ;     "projectNumber": "933037264567",
    ;     "team": "editors"
    ;    },
    ;    "etag": "CLT5kpW71dUCEAE="
    ;   },
    ;   {
    ;    "kind": "storage#objectAccessControl",
    ;    "id": "chilkat-ocean/starfish.jpg/1502670320090292/project-viewers-933037264567",
    ;    "selfLink": "https://www.googleapis.com/storage/v1/b/chilkat-ocean/o/starfish.jpg/acl/project-viewers-933037264567",
    ;    "bucket": "chilkat-ocean",
    ;    "object": "starfish.jpg",
    ;    "generation": "1502670320090292",
    ;    "entity": "project-viewers-933037264567",
    ;    "role": "READER",
    ;    "projectTeam": {
    ;     "projectNumber": "933037264567",
    ;     "team": "viewers"
    ;    },
    ;    "etag": "CLT5kpW71dUCEAE="
    ;   },
    ;   {
    ;    "kind": "storage#objectAccessControl",
    ;    "id": "chilkat-ocean/starfish.jpg/1502670320090292/user-starfish@chilkat-176611.iam.gserviceaccount.com",
    ;    "selfLink": "https://www.googleapis.com/storage/v1/b/chilkat-ocean/o/starfish.jpg/acl/user-starfish@chilkat-176611.iam.gserviceaccount.com",
    ;    "bucket": "chilkat-ocean",
    ;    "object": "starfish.jpg",
    ;    "generation": "1502670320090292",
    ;    "entity": "user-starfish@chilkat-176611.iam.gserviceaccount.com",
    ;    "role": "OWNER",
    ;    "email": "starfish@chilkat-176611.iam.gserviceaccount.com",
    ;    "etag": "CLT5kpW71dUCEAE="
    ;   }
    ;  ],
    ;  "owner": {
    ;   "entity": "user-starfish@chilkat-176611.iam.gserviceaccount.com"
    ;  },
    ;  "crc32c": "9RjgwQ==",
    ;  "etag": "CLT5kpW71dUCEAE="
    ; }
    ; 


    CkStringBuilder::ckDispose(sbToken)
    CkHttp::ckDispose(http)
    CkStringBuilder::ckDispose(sbMetaData)


    ProcedureReturn
EndProcedure