From 478e297e9e3c2944fb20b750463db89f2dea1b72 Mon Sep 17 00:00:00 2001
From: mike12345567 <me@michaeldrury.co.uk>
Date: Fri, 24 Nov 2023 18:11:53 +0000
Subject: [PATCH] Initial work towards aliasing queries for SQL.

---
 .../server/src/api/controllers/row/alias.ts   | 101 ++++++++++++++++++
 packages/server/src/integrations/base/sql.ts  |   1 +
 2 files changed, 102 insertions(+)
 create mode 100644 packages/server/src/api/controllers/row/alias.ts

diff --git a/packages/server/src/api/controllers/row/alias.ts b/packages/server/src/api/controllers/row/alias.ts
new file mode 100644
index 0000000000..8111396ea9
--- /dev/null
+++ b/packages/server/src/api/controllers/row/alias.ts
@@ -0,0 +1,101 @@
+import { QueryJson, SearchFilters, Table, Row } from "@budibase/types"
+import { getDatasourceAndQuery } from "../../../sdk/app/rows/utils"
+import { cloneDeep } from "lodash"
+
+class AliasTables {
+  character: string
+  aliases: Record<string, string>
+  tableAliases: Record<string, string>
+
+  constructor() {
+    this.character = "a"
+    this.aliases = {}
+    this.tableAliases = {}
+  }
+
+  getAlias(tableName: string) {
+    if (this.aliases[tableName]) {
+      return this.aliases[tableName]
+    }
+    this.character = String.fromCharCode(this.character.charCodeAt(0) + 1)
+    this.aliases[tableName] = this.character
+    this.tableAliases[this.character] = tableName
+    return this.character
+  }
+
+  aliasField(tableNames: string[], field: string) {
+    if (field.includes(".")) {
+      const [tableName, column] = field.split(".")
+      if (tableNames.includes(tableName)) {
+        return `${this.getAlias(tableName)}.${column}`
+      }
+    }
+    return field
+  }
+
+  reverse<T extends Row | Row[]>(tableNames: string[], rows: T): T {
+    const process = (row: Row) => {
+      const final: Row = {}
+      for (let [key, value] of Object.entries(row)) {
+        if (!key.includes(".")) {
+          final[key] = value
+        } else {
+          const [alias, column] = key.split(".")
+          const tableName = this.tableAliases[alias] || alias
+          final[`${tableName}.${column}`] = value
+        }
+      }
+      return final
+    }
+    if (Array.isArray(rows)) {
+      return rows.map(row => process(row)) as T
+    } else {
+      return process(rows) as T
+    }
+  }
+
+  async queryWithAliasing(tableNames: string[], json: QueryJson) {
+    json = cloneDeep(json)
+    const aliasField = (field: string) => this.aliasField(tableNames, field)
+    const aliasTable = (table: Table) => ({
+      ...table,
+      name: this.getAlias(table.name),
+    })
+    // run through the query json to update anywhere a table may be used
+    if (json.resource?.fields) {
+      json.resource.fields = json.resource.fields.map(field =>
+        aliasField(field)
+      )
+    }
+    if (json.filters) {
+      for (let [filterKey, filter] of Object.entries(json.filters)) {
+        if (typeof filter !== "object") {
+          continue
+        }
+        const aliasedFilters: typeof filter = {}
+        for (let key of Object.keys(filter)) {
+          aliasedFilters[aliasField(key)] = filter
+        }
+        json.filters[filterKey as keyof SearchFilters] = aliasedFilters
+      }
+    }
+    if (json.relationships) {
+      json.relationships = json.relationships.map(relationship => ({
+        ...relationship,
+        tableName: this.getAlias(relationship.tableName),
+      }))
+    }
+    if (json.meta?.table) {
+      json.meta.table = aliasTable(json.meta.table)
+    }
+    if (json.meta?.tables) {
+      const aliasedTables: Record<string, Table> = {}
+      for (let [tableName, table] of Object.entries(json.meta.tables)) {
+        aliasedTables[this.getAlias(tableName)] = aliasTable(table)
+      }
+      json.meta.tables = aliasedTables
+    }
+    const response = await getDatasourceAndQuery(json)
+    return this.reverse(tableNames, response)
+  }
+}
diff --git a/packages/server/src/integrations/base/sql.ts b/packages/server/src/integrations/base/sql.ts
index 29c8416b34..630c962a15 100644
--- a/packages/server/src/integrations/base/sql.ts
+++ b/packages/server/src/integrations/base/sql.ts
@@ -437,6 +437,7 @@ class InternalBuilder {
 
   read(knex: Knex, json: QueryJson, limit: number): KnexQuery {
     let { endpoint, resource, filters, paginate, relationships } = json
+
     const tableName = endpoint.entityId
     // select all if not specified
     if (!resource) {