Taichi ORM

Schema

  • It represents a dictionary of properties.
  • Dataset, ModelRepository or Model can produce a Schema.

Examples:

context.dataset().schema()

context.repos.Model1.schema()

require('./models/Model1').schema()
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Datasource

  • It is produced from a Schema by giving a name (acts as table alias).
  • It refers to a database table or a temporary table.
  • It is used by the Query Builders' from, innerJoin, leftJoin and rightJoin functions.

Example: Below it makes a query with selecting fields from table Model1 with alias table_alias.

const schema = context.repos.Model1.schema()

let queryBuilder = context.dataset()
    .from(schema.datasource('table_alias'))
    .select(
        'table_alias.id',
        'table_alias.field1',
        'table_alias.field2'
    )



 

 
 
 

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There are many ways to create a datasource instance.

Model1.schema().datasource(string)
//OR a shortcut:
Model1.datasource(string)

modelRepository1.schema().datasource(string)
//OR a shortcut:
modelRepository1.datasource(string)

dataset1.schema().datasource(string)
//OR a shortcut:
dataset1.datasource(string)
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ValueSelector ($)

A datasource instance provides an object $ having values of Scalar or CompiledComputeFunction which represents the properties of the Schema.

TIP

Scalar is a single SQL value that can be a field name or SQL functions.

Please see Scalar for more details.

Examples:

export default class MyModel extends Model {
  // Nullable Integer
  prop1 = this.field(NumberType)
  
  prop2 = this.compute( (parent) => parent.minus(3) )
}

const scalar1 = Model1.datasource('table1').$.prop1

const scalar2 = Model1.datasource('table1').$.prop2()
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If the key of $ refers to a FieldProperty's name, the value will be a Scalar.

If it refers to a ComputeProperty's name, the value is a Function (CompiledComputeFunction) that returns a Scalar.

TIP

Please see Property for more explanation.