JSON Data Definition Language (DDL)

See it in action

There is an available UI to test different JSON structures described here

Check out

• CRUD
• Data Layer Access

We define an array of entities. All entities have attributes and are assigned primary keys in the form of ids or uuids.

Entity

| Arg Name | Possible values | Example | | ----------- | ------------------------------------------------------------------------------------------------------- | ------------ | | name | name of the entity. has to start with a capital letter | "Country" | | table | name of the SQL table. This field is optional, if not given the table is the snake case version of name | my_country | | uuid | boolean, if set to true, the primary key is a uuid vs a id | false | | withOrder | allows ordering (UI: drag/drop) | false | | description | description of the entity, optional | | | logUser | saves user id | false | | isLog | add log logic in table | false | | logTable | creates mirror log table | false | | extends | extends a particular preprogrammed entity (e.g. user) | null | | uniqueSet | array with combination of params that are unique (e.g ["countryId", "userId"]) | null |

Attribute

| Arg Name | Possible values | Default | | ----------- | ------------------------------------- | ----------- | | Name | field name | - | | type | see section | string | | optional | true/false | false | | constraints | see section | [] | | description | description of the attribute | | | ui | {textarea, datepicker, slider, etc..} | fieldType |

Field Types

| Type | Example values | | -------- | -------------------- | | Int | 1, 2, 3 | | Long | 65432345, 2345432345 | | String | hello | | Boolean | true / false | | Decimal | 23.34 | | Date | 2019-01-31 | | Datetime | 2019-01-31 15:23 | | Time | 15:23 | | - | Country |

Every entity name automatically becomes a type. Hence the last example of the table where the type is Country, referring to the entity Country and creating a relation with that other entity.

a more formal version can be found in https://github.com/nexys-system/data-model-definition/blob/master/src/lib/type.ts

mapping SQL JSON-ddl

BigDecimal => Decimal 10, 4
Int => int(11)
Long => bigint(20)
LocalDateTime => Datetime
LocalDate => Datetime

Constraints

| Arg Name | Possible values | Default | | -------- | -------------------------------- | ------- | | typeId | see section | - | | value | value of the constraint | - | | msg | overrides default message | - |

Constraint Types

• 1: equal = (number)
• 2: greater than > (number(
• 3: less than < (number
• 4: greater than or equal >= (number)
• 5: less than or equal <= (number)
• 6: length (string) => https://stackoverflow.com/questions/9043820/regex-to-match-words-of-a-certain-length
• 7: Regex (string)
• 8: belongs to a predefined set: [9, 87, 34] (all)
• 9: async call to API (link to an API request) (string)

Checking format

The format can be checked with the schema-validation: https://github.com/nexys-system/data-model-definition/blob/master/src/lib/schema-validation.ts

Variable types

Explicit variables

Explicit variables need to be explicitly specified when inserting a record (are part of the payload)

Implicit variables

Implicit variables are not explicitly stated. E.g. taken from auth (userId)

System variables

System variables are not speicified in the model.

Examples are:

• id / uuid
• dateAdded
• dateEdited

Example (simple)

This is an example of a simple model, that links countries and cities.

https://github.com/nexys-system/data-model-definition/tree/master/src/example/simple-country-city.json

Example (advanced)

https://github.com/nexys-system/data-model-definition/tree/master/src/example/advanced.ts