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find-object-state.md

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description
Find an object state at a given time using the Python client.

Find an Object State

Step 1. Connect to a database

Connect to an existing database with multiple commit activities.

Code: Connect to an existing database

import os
import time
import datetime
from   terminusdb_client import WOQLClient
from   terminusdb_client import WOQLQuery as WOQL

server_url = "http://127.0.0.1:6363"
db         = "seshat"
user       = "admin"
account    = "admin"
key        = "root"
client     = WOQLClient(server_url)

client.connect(user=user, account=account, key=key, db=db)

Step 2. Get the initial commit

Get the timestamp of the last commit before the date specified in date_string, using the timetuple() method.

Code: Get the timestamp of a commit

date_string = "14/10/2020"
timestamp   = time.mktime(datetime.datetime.strptime(date_string, "%d/%m/%Y").timetuple())

Step 3. Get the subsequent commit

Get the next commit after the timestamp retrieved in step 2 and store commit data in commit_query.

Code: Get the details of the subsequent commit

commit_query = WOQL().using("admin/seshat/local/_commits",
    WOQL().limit(1,
       WOQL.woql_and(
           WOQL().triple("v:Branch", "ref:branch_name",      "v2"),
           WOQL().triple("v:Branch", "ref:ref_commit", "     v:Head"),
           WOQL().path("v:Head",     "ref:commit_parent+",   "v:Tail", "v:Path"),
           WOQL().triple("v:Tail",   "ref:commit_id",        "v:TailID"),
           WOQL().triple("v:Tail",   "ref:commit_timestamp", "v:TimeStamp"),
           WOQL().greater(timestamp, "v:TimeStamp"),
)))

Step 4. Get the commit identifier

Get the commit identifier into variable commit_id after running the commit_query defined in step 3.

Code: Get the commit id

results   = client.query(commit_query)
commit_id = results['bindings'][0]['TailID']['@value']

Step 5. Get the commit object state

Get the commit object associated with the commit_id obtained in step 4. Note the full path of the commit_id.

Code: Get the commit object state

path = f"admin/seshat/local/commit/{commit_id}"

object_query = WOQL().using(path,
        WOQL().read_object("terminusdb:///data/afghazn", "v:Document"))

results = client.query(object_query)

print(results)