TypeScript
ElectroDB using advanced dynamic typing techniques to automatically create types based on the configurations in your model. Changes to your model will automatically change the types returned by ElectroDB.
If you experience any issues using TypeScript with ElectroDB, your feedback is very important, please create a GitHub issue, and it can be addressed.
Type Utilities
ElectroDB exports some functions to assist with the creation of custom types and/or to improve type portability.
CustomAttributeType
The function CustomAttributeType
assists in the creation of custom attributes. This can be helpful to extend the primitive types and/or build complex union types. Check out the recipe Opaque Types to learn more by example.
createSchema
The createSchema
function allows you to define a schema independent of instantiating a new entity. This can be useful if the model definition needs to be portable or dynamic. This function will also validate your schema, and will throw if it is not a valid format.
Exported Types
The following types are exported for easier use while using ElectroDB with TypeScript. The naming convention for the types include three different kinds:
-
xResponse
— Types with the postfixResponse
represent the returned interfaces directly from ElectroDB. -
xItem
— Types with the postfixItem
represent an Entity row. Queries return multiple items, a get returns a single item, etc. The type for an item is inferred based on the attributes and index definitions within your model. For example if your attribute is marked asrequired
then that attribute will never be undefined, if your attribute has a default value then it won’t be required to be supplied onput
,list
attributes must be an array, etc. -
xRecord
— In some cases it is helpful to have a type that represents all attributes of an item without nullable properties. Types with the postfixRecord
contain all properties in a non-nullable format.
The follow highlight many of the types exported utility types from ElectroDB:
QueryResponse Type
The QueryResponse
type is the same type returned by an ElectroDB Query.
Definition:
export type QueryResponse<E extends Entity<any, any, any, any>> = {
data: EntityItem<E>[];
cursor: string | null;
};
Usage:
type EntitySchema = QueryResponse<typeof MyEntity>;
EntityIdentifiers Type
The EntityIdentifiers
type an object containing each of your Entity’s Primary Index composite attributes. It is the object used by get
, update
, patch
, delete
, and remove
to uniquely identify an item.
Definition:
export type EntityIdentifiers<E extends Entity<any, any, any, any>> =
E extends Entity<infer A, infer F, infer C, infer S>
? AllTableIndexCompositeAttributes<A, F, C, S>
: never;
Usage:
type Keys = EntityIdentifiers<typeof MyEntity>;
EntityRecord Type
The EntityRecord
type is an object containing every attribute an Entity’s model.
Definition:
type EntityRecord<E extends Entity<any, any, any, any>> = E extends Entity<
infer A,
infer F,
infer C,
infer S
>
? Item<A, F, C, S, S["attributes"]>
: never;
Usage:
type Item = EntityRecord<typeof MyEntity>;
EntityItem Type
This type represents an item as it is returned from a query. This is different from the EntityRecord
in that this type reflects the required
, hidden
, default
, etc. properties defined on the attribute.
Definition:
export type EntityItem<E extends Entity<any, any, any, any>> = E extends Entity<
infer A,
infer F,
infer C,
infer S
>
? ResponseItem<A, F, C, S>
: never;
Usage:
type Item = EntityItem<typeof MyEntityInstance>;
CollectionItem Type
This type represents an item returned from a collection query, and is similar to EntityItem.
Definition:
export type CollectionItem<
SERVICE extends Service<any>,
COLLECTION extends keyof SERVICE["collections"],
> = SERVICE extends Service<infer E>
? Pick<
{
[EntityName in keyof E]: E[EntityName] extends Entity<
infer A,
infer F,
infer C,
infer S
>
? COLLECTION extends keyof CollectionAssociations<E>
? EntityName extends CollectionAssociations<E>[COLLECTION]
? ResponseItem<A, F, C, S>[]
: never
: never
: never;
},
COLLECTION extends keyof CollectionAssociations<E>
? CollectionAssociations<E>[COLLECTION]
: never
>
: never;
Usage:
type CollectionResults = CollectionItem<
typeof MyServiceInstance,
"collectionName"
>;
CollectionResponse
This type represents the value returned the collection query itself
Definition:
export type CollectionResponse<
SERVICE extends Service<any>,
COLLECTION extends keyof SERVICE["collections"],
> = {
data: CollectionItem<SERVICE, COLLECTION>;
cursor: string | null;
};
Usage:
type CollectionResults = CollectionResponse<
typeof MyServiceInstance,
"collectionName"
>;
CreateEntityItem Type
This type represents an item that you would pass your entity’s put
or create
method
Definition:
export type CreateEntityItem<E extends Entity<any, any, any, any>> =
E extends Entity<infer A, infer F, infer C, infer S>
? PutItem<A, F, C, S>
: never;
Usage:
type NewThing = CreateEntityItem<typeof MyEntityInstance>;
UpdateEntityItem Type
This type represents an item that you would pass your entity’s set
method when using create
or update
.
Definition:
export type UpdateEntityItem<E extends Entity<any, any, any, any>> =
E extends Entity<infer A, infer F, infer C, infer S>
? SetItem<A, F, C, S>
: never;
Usage:
type UpdateProperties = UpdateEntityItem<typeof MyEntityInstance>;
UpdateAddEntityItem Type
This type represents an item that you would pass your entity’s add
method when using create
or update
.
Definition:
export type UpdateAddEntityItem<E extends Entity<any, any, any, any>> =
E extends Entity<infer A, infer F, infer C, infer S>
? AddItem<A, F, C, S>
: never;
UpdateSubtractEntityItem Type
This type represents an item that you would pass your entity’s subtract
method when using create
or update
.
Definition:
export type UpdateSubtractEntityItem<E extends Entity<any, any, any, any>> =
E extends Entity<infer A, infer F, infer C, infer S>
? SubtractItem<A, F, C, S>
: never;
UpdateAppendEntityItem Type
This type represents an item that you would pass your entity’s append
method when using create
or update
.
Definition:
export type UpdateAppendEntityItem<E extends Entity<any, any, any, any>> =
E extends Entity<infer A, infer F, infer C, infer S>
? AppendItem<A, F, C, S>
: never;
UpdateRemoveEntityItem Type
This type represents an item that you would pass your entity’s remove
method when using create
or update
.
Definition:
export type UpdateRemoveEntityItem<E extends Entity<any, any, any, any>> =
E extends Entity<infer A, infer F, infer C, infer S>
? RemoveItem<A, F, C, S>
: never;
UpdateDeleteEntityItem Type
This type represents an item that you would pass your entity’s delete
method when using create
or update
.
Definition:
export type UpdateDeleteEntityItem<E extends Entity<any, any, any, any>> =
E extends Entity<infer A, infer F, infer C, infer S>
? DeleteItem<A, F, C, S>
: never;