@env0/dynamo-easy
Version:
DynamoDB client for NodeJS and browser with a fluent api to build requests. We take care of the type mapping between JS and DynamoDB, customizable trough typescript decorators.
304 lines • 11.6 kB
JavaScript
/**
* @module mapper
*/
import { v4 as uuidv4 } from 'uuid';
import { hasSortKey } from '../decorator/metadata/metadata';
import { metadataForModel } from '../decorator/metadata/metadata-for-model.function';
import { hasType } from '../decorator/metadata/property-metadata.model';
import { BooleanMapper } from './for-type/boolean.mapper';
import { CollectionMapper } from './for-type/collection.mapper';
import { NullMapper } from './for-type/null.mapper';
import { NumberMapper } from './for-type/number.mapper';
import { ObjectMapper } from './for-type/object.mapper';
import { StringMapper } from './for-type/string.mapper';
import { Binary } from './type/binary.type';
import { NullType } from './type/null.type';
import { UndefinedType } from './type/undefined.type';
import { getPropertyPath, typeOf, typeOfFromDb } from './util';
/**
* @hidden
*/
const mapperForType = new Map();
/**
* mapps an item according to given model constructor [its meta data] to attributes
*/
export function toDb(item, modelConstructor) {
const mapped = {};
if (modelConstructor) {
const metadata = metadataForModel(modelConstructor);
/*
* initialize possible properties with auto generated uuid
*/
if (metadata) {
metadata.getKeysWithUUID().forEach(propertyMetadata => {
if (!Reflect.get(item, propertyMetadata.name)) {
Reflect.set(item, propertyMetadata.name, uuidv4());
}
});
}
}
item = getES6ClassProperties(item);
const propertyNames = Object.getOwnPropertyNames(item) || [];
propertyNames.forEach(propertyKey => {
/*
* 1) get the value of the property
*/
const propertyValue = getPropertyValue(item, propertyKey);
let attributeValue;
if (propertyValue === undefined || propertyValue === null) {
// noop ignore because we can't map it
}
else {
/*
* 2) decide how to map the property depending on type or value
*/
let propertyMetadata;
if (modelConstructor) {
propertyMetadata = metadataForModel(modelConstructor).forProperty(propertyKey);
}
if (propertyMetadata) {
if (propertyMetadata.transient) {
// 3a_1) skip transient property
}
else {
// 3a_2) property metadata is defined and property is not marked not transient
attributeValue = toDbOne(propertyValue, getPropertyPath(modelConstructor, propertyKey), propertyMetadata);
}
}
else {
// 3b) no metadata found
attributeValue = toDbOne(propertyValue, getPropertyPath(modelConstructor, propertyKey));
}
if (attributeValue === undefined) {
// no-op transient field, just ignore it
}
else if (attributeValue === null) {
// empty values will be ignored too
}
else {
;
mapped[propertyMetadata ? propertyMetadata.nameDb : propertyKey] = attributeValue;
}
}
});
return mapped;
}
export function toDbOne(propertyValue, propertyPathOrMetadata, propertyMetadata) {
const propertyPath = propertyPathOrMetadata && typeof propertyPathOrMetadata === 'string' ? propertyPathOrMetadata : null;
propertyMetadata = propertyPathOrMetadata && typeof propertyPathOrMetadata !== 'string' ? propertyPathOrMetadata : propertyMetadata;
const explicitType = hasType(propertyMetadata)
? propertyMetadata.typeInfo.type
: null;
const type = explicitType || typeOf(propertyValue, propertyPath);
const mapper = propertyMetadata && propertyMetadata.mapper ? propertyMetadata.mapper() : forType(type);
const attrValue = explicitType
? mapper.toDb(propertyValue, propertyMetadata)
: mapper.toDb(propertyValue);
// some basic validation
if (propertyMetadata && propertyMetadata.key) {
if (attrValue === null) {
throw new Error(`${propertyMetadata.name.toString()} is null but is a ${propertyMetadata.key.type} key`);
}
if (!('S' in attrValue) && !('N' in attrValue) && !('B' in attrValue)) {
throw new Error(`\
DynamoDb only allows string, number or binary type for RANGE and HASH key. \
Make sure to define a custom mapper for '${propertyMetadata.name.toString()}' which returns a string, number or binary value for partition key, \
type ${type} cannot be used as partition key, value = ${JSON.stringify(propertyValue)}`);
}
}
return attrValue;
}
/**
* @hidden
*/
function testForKey(p) {
return !!p.key;
}
/**
* returns the function for the given ModelConstructor to create the AttributeMap with HASH (and RANGE) Key of a given item.
* @param modelConstructor
*/
export function createToKeyFn(modelConstructor) {
const metadata = metadataForModel(modelConstructor);
const properties = metadata.modelOptions.properties;
if (!properties) {
throw new Error('metadata properties is not defined');
}
const keyProperties = properties.filter(testForKey);
return (item) => keyProperties.reduce((key, propMeta) => {
if (item[propMeta.name] === null || item[propMeta.name] === undefined) {
throw new Error(`there is no value for property ${propMeta.name.toString()} but is ${propMeta.key.type} key`);
}
const propertyValue = getPropertyValue(item, propMeta.name);
key[propMeta.nameDb] = toDbOne(propertyValue, propMeta);
return key;
}, {});
}
/**
* creates toKeyFn and applies item to it.
* @see {@link createToKeyFn}
*/
export function toKey(item, modelConstructor) {
return createToKeyFn(modelConstructor)(item);
}
/**
* @hidden
*/
export function createKeyAttributes(metadata, partitionKey, sortKey) {
const partitionKeyProp = metadata.getPartitionKey();
const partitionKeyMetadata = metadata.forProperty(partitionKeyProp);
if (!partitionKeyMetadata) {
throw new Error('metadata for partition key must be defined');
}
const keyAttributeMap = {
[partitionKeyMetadata.nameDb]: toDbOne(partitionKey, partitionKeyMetadata),
};
if (hasSortKey(metadata)) {
if (sortKey === null || sortKey === undefined) {
throw new Error(`please provide the sort key for attribute ${metadata.getSortKey()}`);
}
const sortKeyProp = metadata.getSortKey();
const sortKeyMetadata = metadata.forProperty(sortKeyProp);
if (!sortKeyMetadata) {
throw new Error('metadata for sort key must be defined');
}
keyAttributeMap[sortKeyMetadata.nameDb] = toDbOne(sortKey, sortKeyMetadata);
}
return keyAttributeMap;
}
/**
* parses attributes to a js item according to the given model constructor [its meta data]
*/
export function fromDb(attributeMap, modelConstructor) {
const model = {};
Object.getOwnPropertyNames(attributeMap).forEach(attributeName => {
/*
* 1) get the value of the property
*/
const attributeValue = attributeMap[attributeName];
/*
* 2) decide how to map the property depending on type or value
*/
let modelValue;
let propertyMetadata;
if (modelConstructor) {
propertyMetadata = metadataForModel(modelConstructor).forProperty(attributeName);
}
if (propertyMetadata) {
if (propertyMetadata.transient) {
// skip transient property
}
else {
/*
* 3a) property metadata is defined
*/
if (propertyMetadata && propertyMetadata.mapper) {
// custom mapper
modelValue = propertyMetadata.mapper().fromDb(attributeValue, propertyMetadata);
}
else {
modelValue = fromDbOne(attributeValue, propertyMetadata);
}
}
}
else {
modelValue = fromDbOne(attributeValue);
}
if (modelValue !== null && modelValue !== undefined) {
Reflect.set(model, propertyMetadata ? propertyMetadata.name : attributeName, modelValue);
}
});
return model;
}
/**
* parses an attribute to a js value according to the given property metadata
*/
export function fromDbOne(attributeValue, propertyMetadata) {
const explicitType = hasType(propertyMetadata) ? propertyMetadata.typeInfo.type : null;
const type = explicitType || typeOfFromDb(attributeValue);
if (explicitType) {
return forType(type).fromDb(attributeValue, propertyMetadata);
}
else {
return forType(type).fromDb(attributeValue);
}
}
/**
* @hidden
*/
export function forType(type) {
let mapper = mapperForType.get(type);
if (!mapper) {
switch (type) {
case String:
mapper = StringMapper;
break;
case Number:
mapper = NumberMapper;
break;
case Boolean:
mapper = BooleanMapper;
break;
case Map:
// Maps support complex types as keys, we only support String & Number as Keys, otherwise a .toString() method should be implemented,
// so we now how to save a key
// mapperForType = new MapMapper()
throw new Error('Map is not supported to be mapped for now');
case Array:
mapper = CollectionMapper;
break;
case Set:
mapper = CollectionMapper;
break;
case NullType:
mapper = NullMapper;
break;
case Binary:
throw new Error('no mapper for binary type implemented yet');
case UndefinedType:
mapper = ObjectMapper;
break;
case Object:
default:
// return ObjectMapper as default to support nested @Model decorated classes (nested complex classes)
// just note that the property still needs @Property decoration to get the metadata of the complex type
mapper = ObjectMapper;
}
mapperForType.set(type, mapper);
}
return mapper;
}
/**
* @hidden
*/
export function getPropertyValue(item, propertyKey) {
const propertyDescriptor = Object.getOwnPropertyDescriptor(item, propertyKey);
// use get accessor if available otherwise use value property of descriptor
if (propertyDescriptor) {
if (propertyDescriptor.get) {
return propertyDescriptor.get();
}
else {
return propertyDescriptor.value;
}
}
else {
throw new Error(`there is no property descriptor for item ${JSON.stringify(item)} and property key ${propertyKey}`);
}
}
/**
* @hidden
*/
function getES6ClassProperties(item) {
const jsonObj = Object.assign({}, item);
const proto = Object.getPrototypeOf(item);
for (const key of Object.getOwnPropertyNames(proto)) {
const desc = Object.getOwnPropertyDescriptor(proto, key);
const hasGetter = desc && typeof desc.get === 'function';
if (hasGetter) {
jsonObj[key] = item[key];
}
}
return jsonObj;
}
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