DbModel is an object representing the logical structure of a database.

Constructor

const myDB = // initialize connection
const myModel = new DbModel ({
   db: myDB,
// src: '/my/project/db/model',   //  {root}
// src: ['/my/project/db/model'], // [{root}]
   src: [
     {
//     name: null,   
//     schemaName: 'public',   
       root: // [
         '/my/project/db/model',
//       ...
//     ],
//     filter: (str, arr) => arr.at (-2) === 'Model', // **/Model/*
//     ext: '.js',
//     merger: new myDbObjectMerger (someMergingOptions),
     },
     ...
   ]
})

If db is set, the model injects there a reference to itself: myModel.db.model === myModel.

More on the src option

In general, src is a list of elements corresponding to individual schemata entries.

If the model contains only one schema, src may be a single object instead of a 1-element Array.

A string value may be used instead of the Object element: in this case, the it is considered the root value.

Any model contains the default schema which name is null. The completely missing src acts as src: [{name: null}].

Name	Type	Description
name	String	The logical schema name. null for the default schema. Must be unique across the model.
schemaName	String	The physical schema name. If omitted, defaults to name. Must be unique across the model.
root	String or [String]	see DbSchemaSource
filter	(String, Array) => Boolean	see DbSchemaSource
ext	String	see DbSchemaSource
merger	ObjectMerger	see DbSchemaSource

Properties

Name	Type	Description
schemata	Map	Collection of DbSchemas of the database described
defaultSchema	DbSchema	The default schema behind this model, alias for this.getSchema (null)
db	DbPool	Source of physical connections to the database
lang	DbLang	Normally, a copy of db.lang made by loadModules ()

Events

Name	AKA	Description
'objects-created'	DbModel.EV_OBJECTS_CREATED	Emitted at end of createObjects (). By default, the resolveReferences () invoker is subscribed here.

Methods

User API

Initialization

loadModules

This synchronous method scans schemata and calls schema.src.load () wherever available (thus, loading schema content from module files). At the end, the 'objects-created' event is emitted.

Run time

assignData

For a given record Object and an Array of DbTable names, copies the .data property from each of them to record under the corresponding name. Returns the modified record.

createQuery

This synchronous method takes no parameters and returns a new instance of DbQuery for the underlying database.

find

For a given name in the defaultSchema or ${schemaName}.${objectName}, returns the corresponding DbObject or undefined unless it exists.

objects

This synchronous generator provides the sequence conaining all DbObjects in all schemas of the model.

Internal

addSchema

For a given src element (see above), creates a new DbSchema and stores it into this.schemata.

getSchema

For a given name, returns the corresponding DbSchema.

resolveReferences

This synchronous method scans this.map for DbRelation instances and completes initialization of DbReferences of their columns by setting targetRelation / targetColumnName / targetColumn and copying targetColumn.type to the cost column type.