Simple Data Viewer

- Generic CDS service to fetch data
- Simple Vue.js UI

data-viewer/srv/data-service.js

@@ -0,0 +1,58 @@
+const cds = require('@sap/cds')
+const log = cds.log('data')
+
+class DataService extends cds.ApplicationService { init(){
+
+  this.on ('READ', 'Entities', req => {
+    const { dataSource } = req.req.query
+    const srvPrefixes = cds.db.model.all('service').map(srv => srv.name+'.')
+    const dataSourceFilter = dataSource === 'db'
+      ? e => e['@cds.persistence.skip'] !== true // for DB, excl. entities w/o persistence
+      : e => !!srvPrefixes.find(srvName => e.name.startsWith(srvName)) // only entities reachable from a service
+
+    return cds.db.model.all('entity')
+      .filter (e => req.data && req.data.name ? e.name === req.data.name : true)  // honor name filter from request, if any
+      .filter (e => !e.name.startsWith('DRAFT.'))  // exclude synthetic stuff
+      .filter (e => !e.name.startsWith('DataService.'))  // exclude this service
+      .filter (dataSourceFilter)
+      .sort((e1, e2) => e1.name.localeCompare(e2.name))
+      .map(e => {
+        const columns = Object.entries(e.elements)
+          .filter(([_, el]) => !(el instanceof cds.Association)) // exclude assocs+compositions
+          .map(([name, el]) => { return { name, type: el.type, isKey:!!el.key }})
+        return { name: e.name, columns }
+      })
+    })
+
+  this.on ('READ', 'Data', async req => {
+    const { entity: entityName, dataSource: dataSourceName } = req.req.query
+    if (!entityName)  return req.reject(400, `Must provide 'entity' query`)
+    const entity = cds.db.model.definitions[entityName]
+    if (!entity)  return req.reject(404, 'No such entity: ' + entityName)
+
+    const query = SELECT.from(entity)
+    query.SELECT.limit = req.query.SELECT.limit  // use $skip / $top from request
+
+    const dataSource = findDataSource(dataSourceName, entityName)
+    const res = await dataSource.run(query)
+    return res.map((line) => {
+      const record = Object.entries(line).map(([column, data]) => {return {column, data}})
+      return { record }
+    })
+  })
+
+  return super.init()
+}}
+
+module.exports = { DataService }
+
+function findDataSource(dataSourceName, entityName) {
+  for (let srv of Object.values(cds.services)) { // all connected services
+    if (!srv.name)  continue // FIXME intermediate/pending in cds.services ?
+    if (dataSourceName === srv.name || entityName.startsWith(srv.name+'.')) {
+      log._debug && log.debug(`using ${srv.name} as data source`)
+      return srv
+    }
+  }
+  return cds.services.db // fallback
+}