Bigquery - Insert new data row into table by python

Question

I read many documents about google bigquery-python, but I can't understand how to manage bigquery data by python code.

At first, I make a new table as below.

credentials = GoogleCredentials.get_application_default()
service = build('bigquery', 'v2', credentials = credentials)

project_id = 'my_project'
dataset_id = 'my_dataset'
table_id = 'my_table'

project_ref = {'projectId': project_id}
dataset_ref = {'datasetId': dataset_id,
               'projectId': project_id}
table_ref = {'tableId': table_id,
             'datasetId': dataset_id,
             'projectId': project_id}

dataset = {'datasetReference': dataset_ref}
table = {'tableReference': table_ref}
table['schema'] = {'fields': [
    {'name': 'id', 'type': 'string'},
...
]}

table = service.tables().insert(body = table, **dataset_ref).execute()

And then I want to insert a data into this table, so I tried to do like below.

fetch_list = []
patch = {'key': 'value'}
fetch_list.append(patch)

table = service.tables().patch(body = fetch_list, **table_ref).execute()

But nothing happened.

How can I update new data into bigquery table?

Please show me some example codes.

Answer 1

EDIT Nov 2018:

The answer of this question is outdated already as the google cloud client has evolved considerably since this last post.

The official docs contains all information needed already; here you can find everything needed for streaming insert and this one has a complete overview of all methods available so far (you'll also find Python code examples on each page and each method).

Original Answer:

There are a few different ways that you can use to insert data to BQ.

For a deeper understanding of how the python-api works, here's everything you'll need: bq-python-api (at first the docs are somewhat scary but after you get a hang of it it's rather quite simple).

There are 2 main methods that I use to insert data to BQ. The first one is data streaming and it's supposed to be used when you can insert row by row in a real time fashion. Code example:

import uuid
def stream_data(self, table, data, schema):
    # first checks if table already exists. If it doesn't, then create it
    r = self.service.tables().list(projectId=your_project_id,
                                     datasetId=your_dataset_id).execute()
    table_exists = [row['tableReference']['tableId'] for row in
                    r['tables'] if
                    row['tableReference']['tableId'] == table]
    if not table_exists:
        body = {
            'tableReference': {
                'tableId': table,
                'projectId': your_project_id,
                'datasetId': your_dataset_id
            },
            'schema': schema
        }
        self.service.tables().insert(projectId=your_project_id,
                                     datasetId=your_dataset_id,
                                     body=body).execute()

    # with table created, now we can stream the data
    # to do so we'll use the tabledata().insertall() function.
    body = {
        'rows': [
            {
                'json': data,
                'insertId': str(uuid.uuid4())
            }
        ]
    }
    self.service.tabledata().insertAll(projectId=your_project_id),
                                       datasetId=your_dataset_id,
                                       tableId=table,
                                         body=body).execute(num_retries=5)

Here my self.service is correspondent to your service object.

An example of input data that we have in our project:

data = {u'days_validated': '20', u'days_trained': '80', u'navigated_score': '1', u'description': 'First trial of top seller alg. No filter nor any condition is applied. Skus not present in train count as rank=0.5', u'init_cv_date': '2016-03-06', u'metric': 'rank', u'unix_date': '1461610020241117', u'purchased_score': '10', u'result': '0.32677139316724546', u'date': '2016-04-25', u'carted_score': '3', u'end_cv_date': '2016-03-25'}

And its correspondent schema:

schema = {u'fields': [{u'type': u'STRING', u'name': u'date', u'mode': u'NULLABLE'}, {u'type': u'INTEGER', u'name': u'unix_date', u'mode': u'NULLABLE'}, {u'type': u'STRING', u'name': u'init_cv_date', u'mode': u'NULLABLE'}, {u'type': u'STRING', u'name': u'end_cv_date', u'mode': u'NULLABLE'}, {u'type': u'INTEGER', u'name': u'days_trained', u'mode': u'NULLABLE'}, {u'type': u'INTEGER', u'name': u'days_validated', u'mode': u'NULLABLE'}, {u'type': u'INTEGER', u'name': u'navigated_score', u'mode': u'NULLABLE'}, {u'type': u'INTEGER', u'name': u'carted_score', u'mode': u'NULLABLE'}, {u'type': u'INTEGER', u'name': u'purchased_score', u'mode': u'NULLABLE'}, {u'type': u'STRING', u'name': u'description', u'mode': u'NULLABLE'}, {u'type': u'STRING', u'name': u'metric', u'mode': u'NULLABLE'}, {u'type': u'FLOAT', u'name': u'result', u'mode': u'NULLABLE'}]}

The other way to insert data is to use the job insert function. As you can see in the documentation, it accepts several sources for your data. I have an example of how you can do so by loading the results of a query into another table:

def create_table_from_query(self,
                            query,
                            dest_table,
                            how):
    body = {
        'configuration': {
            'query': {
                'destinationTable': {
                    'projectId': your_project_id,
                    'tableId': dest_table,
                    'datasetId': your_dataset_id
                },
                'writeDisposition': how,
                'query': query,
            },
        }
    }

    response = self.connector.jobs().insert(projectId=self._project_id,
                                            body=body).execute()
    self.wait_job_completion(response['jobReference']['jobId'])

def wait_job_completion(self, job_id):
    while True:
        response = self.connector.jobs().get(projectId=self._project_id,
                                             jobId=job_id).execute()
        if response['status']['state'] == 'DONE':
            return

The how input accepts the available options for this field in the documentation (such as "WRITE_TRUNCATE", or "WRITE_APPEND").

You can load the data from a csv file for instance, in this case, the configuration variable would be defined something along the lines:

"configuration": {
  "load": {
    "fieldDelimiter": "\t"
    "sourceFormat": "CSV"
    "destinationTable": {
      "projectId": your_project_id,
      "tableId": table_id,
      "datasetId": your_dataset_id
    },
    "writeDisposition": "WRITE_TRUNCATE"
    "schema": schema,
    "sourceUris": file_location_in_google_cloud_storage
  },
}

(Using as example a csv file delimited by tabs. It could be a json file as well, the documentation will walk you through the available options).

Running jobs() require some time for it to complete (that's why we created the wait_job_completion method). It should be cheaper though as compared to real time streaming.

Any questions let us know,