Copying content of entities

#interface #forms #binding

Often you want to copy some data from another entity. In this guide we will create a copier that copies the content of Page entities.

utils/EntityCopier.ts

The main class for copying entities.

import { EntityAccessor, FieldMarker, HasManyRelationMarker, HasOneRelationMarker, PRIMARY_KEY_NAME } from '@contember/admin'

export class EntityCopier {
	constructor(private handlers: CopyHandler[] = []) {
	}

	copy(source: EntityAccessor, target: EntityAccessor) {
		for (const handler of this.handlers) {
			if (handler.copy?.({ copier: this, source, target })) {
				return
			}
		}
		for (const [, marker] of source.getMarker().fields.markers) {
			if (marker instanceof FieldMarker) {
				this.copyColumn(source, target, marker)
			} else if (marker instanceof HasOneRelationMarker) {
				this.copyHasOneRelation(source, target, marker)
			} else if (marker instanceof HasManyRelationMarker) {
				this.copyHasManyRelation(source, target, marker)
			}
		}
	}

	public copyHasOneRelation(source: EntityAccessor, target: EntityAccessor, marker: HasOneRelationMarker) {
		for (const handler of this.handlers) {
			if (handler.copyHasOneRelation?.({ copier: this, source, target, marker })) {
				return
			}
		}
		const subEntity = source.getEntity({ field: marker.parameters })
		if (marker.parameters.expectedMutation === 'connectOrDisconnect') {
			if (!subEntity.existsOnServer && subEntity.hasUnpersistedChanges) {
				throw 'cannot copy'
			}
			target.connectEntityAtField(marker.parameters.field, subEntity)
		} else if (
			marker.parameters.expectedMutation === 'anyMutation' ||
			marker.parameters.expectedMutation === 'createOrDelete'
		) {
			const subTarget = target.getEntity({ field: marker.parameters })
			this.copy(subEntity, subTarget)
		}
	}

	public copyHasManyRelation(source: EntityAccessor, target: EntityAccessor, marker: HasManyRelationMarker) {
		for (const handler of this.handlers) {
			if (handler.copyHasManyRelation?.({ copier: this, source, target, marker })) {
				return
			}
		}
		const list = source.getEntityList(marker.parameters)
		const targetList = target.getEntityList(marker.parameters)
		if (marker.parameters.expectedMutation === 'connectOrDisconnect') {
			for (const subEntity of list) {
				if (!subEntity.existsOnServer && subEntity.hasUnpersistedChanges) {
					throw 'cannot copy'
				}
				targetList.connectEntity(subEntity)
			}
		} else if (
			marker.parameters.expectedMutation === 'anyMutation' ||
			marker.parameters.expectedMutation === 'createOrDelete'
		) {
			targetList.disconnectAll()
			for (const subEntity of list) {
				targetList.createNewEntity(target => {
					this.copy(subEntity, target())
				})
			}
		}
	}

	public copyColumn(source: EntityAccessor, target: EntityAccessor, marker: FieldMarker) {
		if (marker.fieldName === PRIMARY_KEY_NAME) {
			return
		}
		for (const handler of this.handlers) {
			if (handler.copyColumn?.({ copier: this, source, target, marker })) {
				return
			}
		}
		const sourceValue = source.getField(marker.fieldName).value
		target.getField(marker.fieldName).updateValue(sourceValue)
	}
}


export interface CopyEntityArgs {
	copier: EntityCopier
	source: EntityAccessor
	target: EntityAccessor
}

export interface CopyHasOneRelationArgs {
	copier: EntityCopier
	source: EntityAccessor
	target: EntityAccessor
	marker: HasOneRelationMarker
}

export interface CopyHasManyRelationArgs {
	copier: EntityCopier
	source: EntityAccessor
	target: EntityAccessor
	marker: HasManyRelationMarker
}

export interface CopyColumnArgs {
	copier: EntityCopier
	source: EntityAccessor
	target: EntityAccessor
	marker: FieldMarker
}

export interface CopyHandler {
	copy?(args: CopyEntityArgs): boolean

	copyHasOneRelation?(args: CopyHasOneRelationArgs): boolean

	copyHasManyRelation?(args: CopyHasManyRelationArgs): boolean

	copyColumn?(args: CopyColumnArgs): boolean
}

utils/ContentCopyHandler.ts

This "plugin" regenerates IDs of references.

import { CopyColumnArgs, CopyHandler, CopyHasManyRelationArgs } from './EntityCopier'
import { generateUuid, PRIMARY_KEY_NAME } from '@contember/admin'

export class ContentCopyHandler implements CopyHandler {
	constructor(private blockEntity: string, private contentField: string, private referencesField: string) {
	}

	copyColumn({ source, marker }: CopyColumnArgs): boolean {
		return source.name === this.blockEntity && marker.fieldName === this.contentField
	}

	copyHasManyRelation({ source, target, copier, marker }: CopyHasManyRelationArgs): boolean {
		if (source.name !== this.blockEntity || marker.parameters.field !== this.referencesField) {
			return false
		}
		const list = source.getEntityList(marker.parameters)
		const targetList = target.getEntityList(marker.parameters)

		targetList.disconnectAll()
		const referenceMapping = new Map<string, string>()
		for (const subEntity of list) {
			const newId = generateUuid()
			referenceMapping.set(subEntity.id as string, newId)
			targetList.createNewEntity(target => {
				copier.copy(subEntity, target())
				target().getField(PRIMARY_KEY_NAME).updateValue(newId)
			})
		}
		const jsonRaw = source.getField(this.contentField).value
		if (typeof jsonRaw !== 'string') {
			return true
		}
		const jsonValue = JSON.parse(jsonRaw, (key, value) => {
			if (key === 'referenceId') {
				return referenceMapping.get(value)
			}
			return value
		})
		target.getField(this.contentField).updateValue(JSON.stringify(jsonValue))

		return true
	}
}

components/CopyHandler.ts

Helper component, which loads the entity, we are copying from, and loads it into a current entity.

import { Component, EntitySubTree, useEntity, useEntitySubTree } from '@contember/admin'
import React, { ReactNode, useEffect, useRef } from 'react'
import { EntityCopier } from './EntityCopier'
import { ContentCopyHandler } from './ContentCopyHandler'

type CopyHandlerProps = { entityName: string; children: ReactNode; parameterName: string }

export const CopyHandler = Component<CopyHandlerProps>((props, environment) => {
	const id = environment.getParameterOrElse(props.parameterName, null)
	if (!id) {
		return null
	}
	return <CopyHandlerInner {...props} id={id} />
})

export const CopyHandlerInner = Component<CopyHandlerProps & { id: string | number }>(() => {
	const entity = useEntity()
	const sourceEntity = useEntitySubTree('source')
	const firstRender = useRef(true)
	useEffect(() => {
		if (!firstRender.current) {
			return
		}
		firstRender.current = false
		const copier = new EntityCopier([
			new ContentCopyHandler('ContentBlock', 'json', 'references'), // configure the content to match your schema
		])
		copier.copy(sourceEntity, entity)
	}, [entity, sourceEntity])
	return null
}, (props) => {
	return (
		<EntitySubTree entity={{
			entityName: props.entityName,
			where: { id: props.id },
		}} alias={'source'}>
			{props.children}
		</EntitySubTree>
	)
})

pages/article.ts

Usage on some page.

import { Component, CreatePage, EditPage, LinkButton } from '@contember/admin'
import React from 'react'
import { CopyHandler } from './CopyHandler'


const ArticleForm = Component(() => {
	return <>
		{/*form fields*/}
	</>
})

export const create = (
	<CreatePage
		entity="Article"
		rendererProps={{
			title: 'Create new article',
		}}
		redirectOnSuccess={'article/edit(id: $entity.id)'}
	>
		<ArticleForm />
		<CopyHandler entityName={'Article'} parameterName={'copyFrom'}>
			<ArticleForm />
		</CopyHandler>
	</CreatePage>
)

export const edit = (
	<EditPage entity="Article(id=$id)" rendererProps={{ title: 'Edit article' }}>
		<ArticleForm />
		<LinkButton to={'article/create(copyFrom: $entity.id)'}>Create copy</LinkButton>
	</EditPage>
)