Import CSV into google cloud datastore

问题:

I have a CSV file with 2 columns and 20,000 rows I would like to import into Google Cloud Datastore. I'm new to the Google Cloud and NoSQL databases. I have tried using dataflow but need to provide a Javascript UDF function name. Does anyone have an example of this? I will be querying this data once it's in the datastore. Any advice or guidance on how to create this would be appreciated.

回答1:

Using Apache Beam, you can read a CSV file using the TextIO class. See the TextIO documentation.

Pipeline p = Pipeline.create();

p.apply(TextIO.read().from("gs://path/to/file.csv"));

Next, apply a transform that will parse each row in the CSV file and return an Entity object. Depending on how you want to store each row, construct the appropriate Entity object. This page has an example of how to create an Entity object.

.apply(ParDo.of(new DoFn<String, Entity>() {
    @ProcessElement
    public void processElement(ProcessContext c) {
        String row = c.element();
        // TODO: parse row (split) and construct Entity object
        Entity entity = ...
        c.output(entity);
    }
}));

Lastly, write the Entity objects to Cloud Datastore. See the DatastoreIO documentation.

.apply(DatastoreIO.v1().write().withProjectId(projectId));

回答2:

Simple in python, but can easily adapt to other langauges. Use the split() method to loop through the lines and comma-separated values:

from google.appengine.api import urlfetch
from my.models import MyModel

csv_string   = 'http://someplace.com/myFile.csv'
csv_response = urlfetch.fetch(csv_string, allow_truncated=True) 

if csv_response.status_code == 200:
    for row in csv_response.content.split('\n'):
        row_values = row.split(',')
        # csv values are strings.  Cast them if they need to be something else
        new_entry = MyModel(
            property1 = row_values[0],
            property2 = row_values[1]
        )
        new_entry.put()

else:
    print 'cannot load file: {}'.format(csv_string)