TypeError: Cannot read property 'databaseName' of undefined
Problem
Issue type: [x] bug report Database system/driver: [x] `mssql` TypeORM version: [x] `latest` Steps to reproduce or a small repository showing the problem: Here is a repo with the bug: https://github.com/victorschinaider/typeorm-bug I think `pagination`+ `embedded orderBy`+ `subquery` + `leftJoinAndSelect` combination is giving me the problem.
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1 Fix
Fix TypeError: Cannot read property 'databaseName' of undefined in TypeORM with MSSQL
The error occurs when attempting to access the 'databaseName' property of an undefined object, likely due to an incorrect configuration or missing parameters in the TypeORM query. This can happen when using complex query combinations, such as pagination with embedded orderBy and subqueries, especially when left joins are involved.
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- 1
Check Database Connection Configuration
Ensure that your TypeORM connection configuration includes all necessary parameters, particularly the database name. If the database name is not specified, TypeORM may fail to establish a connection, leading to the observed error.
typescriptconst connectionOptions = { type: 'mssql', host: 'localhost', port: 1433, username: 'user', password: 'password', database: 'your_database_name' }; - 2
Verify Query Structure
Review the query structure to ensure that all necessary fields are being selected and that the joins are correctly defined. Pay special attention to the leftJoinAndSelect usage to ensure that the relationships are properly established.
typescriptconst results = await repository.createQueryBuilder('entity') .leftJoinAndSelect('entity.relatedEntity', 'related') .orderBy('entity.someField', 'ASC') .skip(pagination.skip) .take(pagination.take) .getMany(); - 3
Add Error Handling
Implement error handling in your query execution to catch and log any errors that may provide more context about the failure, which can help in debugging.
typescripttry { const results = await repository.find(); } catch (error) { console.error('Error fetching data:', error); } - 4
Update TypeORM and Driver
Ensure that both TypeORM and the MSSQL driver are updated to the latest versions, as bugs may have been fixed in recent releases that could resolve this issue.
bashnpm install typeorm@latest mssql@latest - 5
Test with Simplified Query
Temporarily simplify your query to isolate the issue. Remove pagination, embedded orderBy, and subqueries to determine if the error persists. Gradually reintroduce complexity to identify the specific cause.
typescriptconst results = await repository.createQueryBuilder('entity').getMany();
Validation
Confirm the fix by running the application and executing the query that previously caused the error. Ensure that the query returns the expected results without throwing the TypeError. Additionally, check the logs for any error messages.
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Environment
Submitted by
Alex Chen
2450 rep