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Improved generic handler remote services

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This commit is contained in:
Uwe Klinger
2021-05-14 08:55:17 +02:00
parent 7ae992c5bb
commit fb5d00bbe0
3 changed files with 289 additions and 109 deletions
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301
notes/srv/RemoteHandler.js
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@@ -1,71 +1,33 @@
function getEntity(absoluteName) {
const [serviceName, entityName] = absoluteName.split(".");
return cds.services[serviceName].entities[entityName];
}
function fixColumnName(entity, name) {
const fullName = `${entity.name}.${name}`;
return RemoteHandler.columnNameFixes[fullName] || name;
}
function associationLink(entity, associationName) {
const association = entity.associations[associationName];
const cardinalityMax = association.cardinality && association.cardinality.max;
if (!association)
throw new Error(
`Association "${associationName}" does not exists for entity "${entity.name}".`
);
if (association.keys) {
return associationKey(entity, association);
}
if (association.on && association.on.length === 3 && association.on[0].ref[0] === associationName && association.on[1] === "=" ) {
const keyFieldName = fixColumnName(entity, association.on[2].ref[0]);
const targetKeyFieldName = association.on[0].ref.slice(1).join("_");
return [keyFieldName, targetKeyFieldName, association.target, cardinalityMax];
}
if (association.on) {
const { reverseAssociationName } = associationOn(entity, association);
const targetEntity = getEntity(association.target);
const reverseAssociation =
targetEntity.associations[reverseAssociationName];
const [targetKeyFieldName, keyFieldName] = associationKey(
targetEntity,
reverseAssociation
);
return [keyFieldName, targetKeyFieldName, association.target, cardinalityMax];
}
throw new Error(
`Association "${associationName}" of entity "${entity.name}" has no "on" and no "keys".`
);
/**
*
* @param {string} msg
* @returns {never}
*/
function throwError(msg) {
throw new Error(msg);
}
function associationOn(entity, association) {
if (
!association.on.length === 3 ||
association.on[1] !== "=" ||
association.on[2].ref[0] !== "$self"
)
throw new Error(
`Association "${association.name}" for "${entity.name}" has not the expected form.`
);
const reverseAssociationName = association.on[0].ref[1];
const [targetServiceName, targetEntityName] = association.target.split(".");
return { targetServiceName, targetEntityName, reverseAssociationName };
/**
* @param {{name: string}|string} entity
* @param {{name: string}|string} association
* @param {string} msg
* @returns {never}
*/
function throwAssocError(entity, association, msg) {
throw new Error(`Error with association "${association.name || association}" of entity "${entity.name || entity}": ${msg}`);
}
function associationKey(entity, association) {
const key = association.keys && association.keys[0];
if (!key)
throw new Error(
`Association "${association.name}" for entity "${entity.name}" has no keys.`
);
return [key["$generatedFieldName"], key.ref[0], association.target, association.cardinality.max];
function getEntity(absoluteName) {
const [serviceName, entityName] = absoluteName.split(".");
return cds.services[serviceName]?.entities[entityName] || throwError(`Unknown entity "${absoluteName}"`);
}
class RemoteHandler {
constructor(service, remoteEntities) {
@@ -91,8 +53,8 @@ class RemoteHandler {
const associationName = expand.ref[0];
// Get association target
const [keyFieldName, targetKeyFieldName, targetEntityName, cardinalityMax] =
associationLink(req.target, associationName);
const {keyFieldName, targetKeyFieldName, target, is2many, is2one} =
this.association(req.target, associationName);
// Request all associated entities
// REVISIT: Still needed?
@@ -110,25 +72,22 @@ class RemoteHandler {
if (expandColumns.indexOf(targetKeyFieldName) < 0)
expandColumns.push(targetKeyFieldName);
const targetService = this.serviceFor(targetEntityName);
const targetService = this.serviceFor(target.name);
// Select target
const targetQuery = SELECT.from(targetEntityName)
const targetQuery = SELECT.from(target.name)
.where({ [targetKeyFieldName]: ids })
.columns(expandColumns);
const targetResult = await targetService.run(targetQuery);
let targetResultMap;
switch (cardinalityMax) {
case '1':
if (is2one) {
targetResultMap = this.mixinExpand_to_1(targetResult, targetKeyFieldName);
break;
case '*':
} else if (is2many) {
targetResultMap = this.mixinExpand_to_many(targetResult, targetKeyFieldName);
break;
default:
throw new Error(`Association with cardinality may ${cardinalityMax} is not supported.`);
} else {
throwAssocError(req.target, associationName, `Unsupported cardinality.`);
}
const resultArray = Array.isArray(result) ? result : [ result ];
@@ -160,6 +119,27 @@ class RemoteHandler {
return targetResultMap;
}
/**
* @example
* Notes(24B58115-E394-423B-BEAB-53419A32B927)/supplier
*
* -->
* { SELECT: { from: { ref: {[
* [ id: 'NotesService.Notes',
* where: [
* ref: [ 'ID' ],
* '=',
* val: ''545A3CF9-84CF-46C8-93DC-E29F0F2BC6BE'
* ],
* ],
* [ 'supplier' ]
* ]}}}
*
*
* @param {*} req
* @param {*} next
* @returns
*/
async resolveNavigation(req, next) {
const select = req.query.SELECT;
if (select.from.ref.length !== 2) {
@@ -168,26 +148,37 @@ class RemoteHandler {
);
}
// Get target
const entityName = select.from.ref[0].id;
const entityName = select.from.ref[0].id || throwError(`Missing source entity name for navigation`);
const entity = getEntity(entityName);
const associationName = select.from.ref[1] || throwError(`Missing association name for navigation`);
const [keyFieldName, targetKeyFieldName, targetEntityName] =
associationLink(entity, select.from.ref[1]);
const {keyFieldName, targetKeyFieldName, target, is2many, is2one} = this.association(entity, associationName);
const sourceService = this.serviceFor(entityName);
const targetService = this.serviceFor(targetEntityName);
const targetService = this.serviceFor(target.name);
const selectOne = SELECT.one([keyFieldName])
if (sourceService === targetService) return await next();
// REVISIT: How to call service datasource w/o handlers
const selectEntry = SELECT.one([keyFieldName])
.from(entityName)
.where(select.from.ref[0].where);
const entry = await sourceService.run(selectOne);
const entry = await sourceService.run(selectEntry);
// REVISIT: How to call service datasource w/o handlers
// TODO: Seems not to respect filter for targetkeyFieldName
const selectTarget = SELECT(req.query.SELECT.columns)
.from(targetEntityName)
.from(target)
.where({ [targetKeyFieldName]: entry[keyFieldName] });
return await targetService.run(selectTarget);
}
const result = await targetService.run(selectTarget);
if (is2many) {
return result;
} else if (is2one) {
return result?.[0];
} else {
throw new Error('Unsupported association cardinality');
}
}
async handle(req, next) {
let doRequest;
@@ -198,25 +189,28 @@ class RemoteHandler {
) {
doRequest = () => this.resolveNavigation(req, next)
} else {
const targetService = this.serviceFor(req.target.name);
doRequest = targetService === this.service ?
next : () => targetService.run(req.query)
doRequest = this.isRemote(req.target.name) ?
() => this.serviceFor(req.target.name).run(req.query) : next;
}
return this.resolveExpands(req, doRequest);
}
isRemote(entityName) {
return this.serviceFor(entityName) !== this.service;
}
isSeparated(entityNameA, entityNameB) {
return this.serviceFor(entityNameA) !== this.serviceFor(entityNameB);
}
async resolveExpands(req, next) {
const select = req.query.SELECT;
const expandFilter = (column) => {
if (!column.expand) return false;
const associationName = column.ref[0];
const associationTargetName =
req.target.associations[associationName].target;
return (
this.remoteEntities[associationTargetName] !==
this.remoteEntities[req.target.name]
);
return this.isSeparated(req.target.name, req.target.associations[associationName].target);
};
const expands = select.columns.filter(expandFilter);
@@ -224,17 +218,20 @@ class RemoteHandler {
if (expands.length === 0) return next();
const temporaryKeyFieldNames = [];
for (const expand of expands) {
const associationName = expand.ref[0];
const [keyFieldName] = associationLink(req.target, associationName);
const {keyFieldName} = this.association(req.target, associationName);
// Make sure id property is contained in select
if (
!select.columns.find((column) =>
column.ref.find((ref) => ref == keyFieldName)
)
)
) {
select.columns.push({ ref: keyFieldName });
temporaryKeyFieldNames.push(keyFieldName);
}
}
// Call service implementation
@@ -244,8 +241,134 @@ class RemoteHandler {
expands.map((expand) => this.mixinExpand(req, result, expand))
);
if (temporaryKeyFieldNames.length > 0) {
for (const entry of result) {
for (const name of temporaryKeyFieldNames)
delete entry[name];
}
}
return result;
}
association(entity, associationName, recursion = 0) {
let associationMetaData;
if (++recursion > 2) throwAssocError(entity, association, "Association has recursive definition.");
const association = entity.associations[associationName] || throwAssocError(entity, associationName, `Association does not exists`);
associationMetaData = this.associationKey(entity, association);
if (!associationMetaData) {
associationMetaData = this.associationOn(entity, association);
}
if (!associationMetaData) {
associationMetaData = this.associationOnSelf(entity, association, recursion);
}
if (!association) throwAssocError(entity, association, "Only associations with one key field or on conidition with one field are supported.");
associationMetaData.is2many = association.is2many;
associationMetaData.is2one = association.is2one;
associationMetaData.entity = entity;
associationMetaData.target = getEntity(association.target);
return associationMetaData;
}
/**
* Association with "on" condition
*
* @example
* entity Notes {
* supplier_ID : Suppliers:ID;
* supplier: Association to Suppliers on supplier.ID = supplier_ID;
* }
*
* -->
*
* { association: { on: { [
* ref: [ 'supplier', 'ID' ], // <association>.<target-field>
* '=',
* ref: [ 'supplier_ID' ] // <source-field>
* ] }}}
*
* @param {*} entity
* @param {*} association
* @returns
*/
associationOn(entity, association) {
const onLength = association.on?.length ?? 0;
if (onLength === 0) return;
const on = association.on;
if (!(onLength === 3 && on[0]?.ref?.[0] === association.name && on[1] === "=" && on[2]?.ref[0] !== "$self")) return; //throwAssocError(entity, association, "Association on condition must compare to $self");
return {
keyFieldName: fixColumnName(entity, association.on[2].ref[0]),
targetKeyFieldName: association.on[0].ref.slice(1).join("_")
}
}
/**
*
* @example
* extend entity BusinessPartner {
* notes: Composition of many Notes on notes = $self;
* }
*
* @param {*} entity
* @param {*} association
* @returns
*/
associationOnSelf(entity, association, recursion) {
const onLength = association.on?.length ?? 0;
if (onLength === 0) return;
const on = association.on;
if (!(onLength === 3 && on[0]?.ref && on[1] === "=" && on[2]?.ref[0] === "$self")) return; //throwAssocError(entity, association, "Association on condition must compare to $self");
const reverseAssociationName = association.on[0].ref[1];
const reverseAssociationMetaData = this.association(targetEntity, reverseAssociationName, false);
return {
keyFieldName: reverseAssociationMetaData.targetKeyFieldName,
targetKeyFieldName: reverseAssociationMetaData.keyFieldName
}
}
/**
* Association with keys
*
* @example
* entity Notes {
* supplier: Association to Suppliers;
* }
*
* -->
*
* { association: keys: [ {
* $generatedFieldName: 'supplier_ID',
* ref: [ 'ID' ]
* } ]
* }
*
* @param {*} entity
* @param {*} association
* @returns
*/
associationKey(entity, association) {
const keyLength = association.keys?.length ?? 0;
if (keyLength === 0) return;
if (keyLength > 1) throwAssocError(entity, association, `Association has ${keyLength} key fields, but only 1 is supported.`);
const key = association.keys[0];
return {
keyFieldName: key["$generatedFieldName"] || throwError(entity, association, "Missing $generatedFieldName"),
targetKeyFieldName: key.ref[0] || throwError(entity, association, "Missing key ref")
}
}
}
RemoteHandler.columnNameFixes = {};