Querying Column Items

Preface

Querying column items is useful when you want to get the unique values of a specific column or just want to get all the values of a specific column. By using kala server we can leverage the power of querying column items includes

• Query only unique values using distinct
• Pagination to limit the result
• Filtering data using CQL 2 Filter

Request Structure

Query parameter consist of this fields:

• filter: (object) Optional, CQL 2 Filter to filter the data may include other column, for now only support textual CQL 2 filter maybe in unforseeable future we will support JSON CQL 2 Filter
• page: (number) Optional, page number for pagination
• perPage: (number) Optional, limit the result per page

Response structure

The response will be

{
    "data": [1,2,3]
    "pagination": {
        "page": 1,
        "perPage": 10,
        "total": 30
    }
}

Example

For the sake of quick writing, because of the limited time we have, so here we go the example directly.

Let’s say we have a PostGIS datastore called postgis_sample and a collection called city which has the following columns

• name (string)
• population (number)
• area (number)
• province (string)
• geom (geometry)

Simple

POST /api/data/datastore/postgis_sample/collection/countries/columns/province/items?unique=false&page=1&perPage=5
Content-Type: application/json

{
    "data": ["JATENG", "JATENG", "JAWA BARAT", "JAWA BARAT", "DKI JAKARTA"],
    "pagination": {
        "page": 1,
        "perPage": 5,
        "total": 100
    }
}

Unique

POST /api/data/datastore/postgis_sample/collection/countries/columns/province/items?unique=true&page=1&perPage=5
Content-Type: application/json

{
    "data": ["JATENG", "JAWA BARAT", "DKI JAKARTA", "BALI", "SUMATERA UTARA"],
    "pagination": {
        "page": 1,
        "perPage": 5,
        "total": 38
    }
}

Unique + Filter

POST /api/data/datastore/postgis_sample/collection/countries/columns/province/items?unique=true&page=1&perPage=5&filter=province LIKE 'JA%'
Content-Type: application/json

{
    "data": ["JATENG", "JAWA BARAT", "DKI JAKARTA", "JAMBI", "JAWA TIMUR"],
    "pagination": {
        "page": 1,
        "perPage": 5,
        "total": 5
    }
}