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Get table meta

Describes a table : the name and the type of every column (or of every field found in a MongoDB collection), in the same format for every database. Migration scripts use it to check whether a column exists before adding it.
Method POST
URL /api/system-api/admin/get-table-meta : admin is the user path of your account
Body { instance, database, collection } or an array of them
Answer data : an array of fields, or an array of arrays
From code g.sys.system.getTableMeta

The call

Body
{ "instance": "mysql8", "database": "inventory", "collection": "customers" }
Answer
{
    "success": true,
    "statusCode": 200,
    "data": [
        { "name": "customer_id", "path": "customer_id", "count": 24, "total_count": 24, "type": "Number", "has_duplicates": false, "probability": 1 },
        { "name": "first_name", "path": "first_name", "count": 24, "total_count": 24, "type": [ "String", "Null" ], "has_duplicates": true, "probability": 1 }
    ]
}
Key Meaning
name, path The column, with its path for nested MongoDB fields.
type The type, or the list of types seen (MongoDB).
count, total_count, probability For MongoDB, in how many of the sampled documents the field appears.
has_duplicates Whether the same value appears twice in the sample.
  • table works in place of collection. An array of tables answers an array of arrays, in the same order.
  • A table of a tenant : "instance": "crm::acme", or the header x-am-tenant-username.

From code

A migration which adds a column once
const meta = await g.sys.system.getTableMeta({ instance: 'mysql8', database: 'inventory', table: 'order_transactions' });
if (!meta.find(c => c.name === 'description')) {
    await g.sys.system.executeQuery({ instance: 'mysql8', query: 'ALTER TABLE `inventory`.`order_transactions` ADD COLUMN `description` varchar(255) NULL' });
}

Access and settings

  • Over HTTP, a system API answers once its settings give it apiAccessType: TOKEN_ACCESS (the token of an API user whose group grants this system API, in x-am-authorization) or IS_PUBLIC. Without settings it is NO_ACCESS : your code calls it through g.sys, the admin panel tests it, and an HTTP call is refused.
  • The settings can also cache the answer or require person tokens (authProviders) ; pre and post hooks run around it like around any API.
  • The request headers apply : x-am-response-case, x-am-content-type-response, x-am-internationalization, x-am-tenant-username…

Errors

Code When
400 The body is wrong : the message names the missing or invalid key.
401 No valid API user token, or the API is NO_ACCESS : You are not authorized to access this API.
403 No group grants this system API.