Can Google App Engine Datastore Search for Entities with a Prefix in their Name?

Searching for Strings Prefixed with a Prefix in Google App Engine Datastore

When dealing with large datasets, finding specific data can be a challenging task. In Google App Engine's datastore, one may wish to search for all entities whose names begin with a specific string prefix.

Question:

Can entities in datastore be searched by a name that starts with a prefix?

Answer:

Yes, searching for entities with a name prefix is possible in datastore.

To achieve this, you need to create a query with a combination of two inequality filters. Let's assume we want to find Places with the prefix "li."

GQL Query:

<code class="gql">SELECT * FROM Places WHERE Name > 'li' AND Name < 'lj'

Go Query:

<code class="go">q := datastore.NewQuery("Places").Filter("Name >", "li").Filter("Name <", "lj")</code>

This query will list Places whose names are lexicographically greater than or equal to "li" and lexicographically less than "lj." Hence, results will include names like "liam," "lisotto," and "lizst" but exclude "abc," "ljoi," and "qwerty."

Note: Small and capital letters hold distinct positions in lexicographical order. As such, "List" is considered less than "li," even though "list" is greater than "li."

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