[CLI] Refactor & simplify schema helpers (#11896)

Co-authored-by: Tobbe Lundberg <tobbe@tlundberg.com>

packages/cli/src/lib/schemaHelpers.js

@@ -10,38 +10,38 @@ import { singularize, isPlural } from './rwPluralize'
 import { getPaths } from './'
 
 /**
- * Used to memoize results from `getSchema` so we don't have to go through
- * the work of open the file and parsing it from scratch each time getSchema()
+ * Used to memoize results from `getSchema()` so we don't have to go through
+ * the work of opening and parsing the file from scratch each time `getSchema()`
  * is called with the same model name.
  */
 const schemaMemo = {}
 
 /**
- * Searches for the given model (ignoring case) in schema.prisma
+ * Searches for the given model (ignoring case) in `schema.prisma`
  * and returns the name as it is written by the user, or
  * `undefined` if no model could be found
  */
 const getExistingModelName = async (name) => {
   if (!name) {
     return undefined
   }
-  // Support PascalCase, camelCase, kebab-case, UPPER_CASE, and lowercase model
-  // names
-  const modelName = name.replace(/[_-]/g, '').toLowerCase()
 
+  // Support PascalCase, camelCase, kebab-case, UPPER_CASE,
+  // and lowercase model names
+  const modelName = name.replace(/[_-]/g, '').toLowerCase()
   for (let model of Object.values(schemaMemo)) {
     if (model.name.toLowerCase() === modelName) {
       return model.name
     }
   }
 
-  const schema = await getSchemaDefinitions()
-
-  for (let model of schema.datamodel.models) {
+  const schema = (await getSchemaDefinitions()).datamodel
+  for (let model of schema.models) {
     if (model.name.toLowerCase() === modelName) {
       return model.name
     }
   }
+
   return undefined
 }
 
@@ -51,64 +51,63 @@ const getExistingModelName = async (name) => {
  * entire schema is returned.
  */
 export const getSchema = async (name) => {
-  if (name) {
-    const modelName = await getExistingModelName(name)
-    if (!modelName) {
-      throw new Error(
-        `No schema definition found for \`${name}\` in schema.prisma file`,
-      )
-    }
-    if (!schemaMemo[modelName]) {
-      const schema = await getSchemaDefinitions()
-      const model = schema.datamodel.models.find((model) => {
-        return model.name === modelName
-      })
-
-      if (model) {
-        // look for any fields that are enums and attach the possible enum values
-        // so we can put them in generated test files
-        model.fields.forEach((field) => {
-          const fieldEnum = schema.datamodel.enums.find((e) => {
-            return field.type === e.name
-          })
-          if (fieldEnum) {
-            field.enumValues = fieldEnum.values
-          }
-        })
-
-        // memoize based on the model name
-        schemaMemo[modelName] = model
-      }
-    }
+  const schema = (await getSchemaDefinitions()).datamodel
+
+  if (!name) {
+    return schema
+  }
+
+  const modelName = await getExistingModelName(name)
+  if (!modelName) {
+    throw new Error(
+      `No schema definition found for \`${name}\` in schema.prisma file`,
+    )
+  }
+
+  if (schemaMemo[modelName]) {
     return schemaMemo[modelName]
-  } else {
-    return (await getSchemaDefinitions()).datamodel
   }
+
+  const model = schema.models.find((model) => model.name === modelName)
+  if (!model) {
+    // TODO: Can this happen, and if yes, should we prefer throwing an error?
+    return undefined
+  }
+
+  // Look for any fields that are enums and attach the possible enum values
+  // so we can put them in generated test files
+  model.fields.forEach((field) => {
+    const fieldEnum = schema.enums.find((e) => field.type === e.name)
+    if (fieldEnum) {
+      field.enumValues = fieldEnum.values
+    }
+  })
+
+  // Memoize based on the model name
+  schemaMemo[modelName] = model
+
+  return model
 }
 
 /**
- * Returns the enum defined with the given `name` parsed from
- * the schema.prisma of the target application. If no `name` is given then the
- * all enum definitions are returned
+ * Returns the enum defined with the given `name` parsed from the
+ * `schema.prisma` of the target application. If no `name` is given
+ * then all enum definitions are returned
  */
 export const getEnum = async (name) => {
   const schema = await getSchemaDefinitions()
+  if (!name) {
+    return schema.metadata.datamodel.enums
+  }
 
-  if (name) {
-    const model = schema.datamodel.enums.find((model) => {
-      return model.name === name
-    })
-
-    if (model) {
-      return model
-    } else {
-      throw new Error(
-        `No enum schema definition found for \`${name}\` in schema.prisma file`,
-      )
-    }
+  const model = schema.datamodel.enums.find((model) => model.name === name)
+  if (!model) {
+    throw new Error(
+      `No enum schema definition found for \`${name}\` in schema.prisma file`,
+    )
   }
 
-  return schema.metadata.datamodel.enums
+  return model
 }
 
 /*
@@ -128,11 +127,10 @@ export const getSchemaDefinitions = () => {
 /*
  * Returns the config info defined in `schema.prisma` (provider, datasource, etc.)
  */
-export const getSchemaConfig = () => {
-  return getConfig({
+export const getSchemaConfig = () =>
+  getConfig({
     datamodel: getDataModel(),
   })
-}
 
 export async function verifyModelName(options) {
   const modelName =