Queries

Deta Base supports queries for fetching data that match certain conditions. Queries are regular objects/dicts/maps with conventions for different operators for specifying the conditions.

Operators

Queries support the following operators:

Equal

{"age": 22, "name": "Beverly"}

// hierarchical
{"user.profile.age": 22, "user.profile.name": "Beverly"}

{"fav_numbers": [2, 4, 8]}

{"time": {"day": "Tuesday", "hour": "08:00"}}

Not Equal

{"user.profile.age?ne": 22}

Less Than

{"user.profile.age?lt": 22}

Greater Than

{"user.profile.age?gt": 22}

Less Than or Equal

{"user.profile.age?lte": 22}

Greater Than or Equal

{"user.profile.age?gte": 22}

Prefix

{"user.id?pfx": "afdk"}

Range

{"user.age?r": [22, 30]}

Contains

{
  // if user email contains the substring @deta.sh
  "user.email?contains": "@deta.sh" 
}

{
  // if berlin is in a list of places lived 
  "user.places_lived_list?contains": "berlin"
}

Not Contains

{
  // if user email does not contain @deta.sh
  "user.email?not_contains": "@deta.sh" // 'user.email?!contains' also valid
}

{
  // if berlin is not in a list of places lived
  "user.places_lived_list?not_contains": "berlin" // 'user.places_lived_list?!contains' also valid
}

?contains and ?not_contains only works for a list of strings if checking for membership in a list; it does not apply to list of other data types. You can store your lists always as a list of strings if you want to check for membership.

Logical Operators

AND

The entries in a single query object are AND ed together. For e.g. the query:

{
    "active": true, 
    "age?gte": 22 
}

will retrieve items where active is true and age is greater than or equal to 22.

The query above would translate to SQL as:

SELECT * FROM base WHERE active=1 AND age>=22;

OR

Multiple query objects in a list are OR ed together. For eg. the queries:

[{"age?lte": 30}, {"age?gte": 40}]

will retrieve items where age is less than equal to 30 or age is greater than equal to 40.

The query above would translate to SQL as:

SELECT * FROM base WHERE age<=30 OR age>=40;

Hierarchy

You can use the period character . to query for hierarchical fields within the data. For instance if you have the following item in the base:

{
    "key": "user-key",
    "profile": {
        "age": 22, 
        "active": true 
    }
}

Then you can query for the active and age within profile directly:

{
    "profile.age": 22,
    "profile.active": true
}

Querying Keys

You need to consider the following when querying on keys:

• The keys must be strings hence the operation values must also be strings.

• The contains and not-contains operators are not supported.

• The AND and OR operations for different query values are not supported. For e.g. the following queries are invalid:

  {
      // different AND key queries (invalid query)
      "key": "a",
      "key?pfx": "b"
  }

  {
      // different OR key queries (invalid query)
      [{"key?pfx":"a"}, {"key?pfx": "b"}]
  }