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postgresqldelphipostgisfiredacbytea

FireDAC: How to avoid "Cannot describe type" error? (on a postgres geometry column)

I have read in the documentation (http://docwiki.embarcadero.com/RADStudio/Tokyo/en/Defining_Connection_(FireDAC)) that one must set the connection parameter "UnknownFormat" to "BYTEA", to avoid this error. However, I have set that parameter and still get that error.

Details: A simple VCL forms application with an FDConnection and an FDQuery. Tested the FDConnection and set the UnknownFormat parameter to ufBYTEA. Put an SQL select statement in the FDQuery which selects a geometry field from a table. On Execute I get the error.

Solution

  • Reproduced in Delphi Tokyo 10.2.3 with PostgreSQL 10.1, PostGIS 2.4.3. Issue report RSP-20251.

    But I believe it's irrelevant as I guess you've simply returned raw geometry data (as they are stored by PostGIS) without proper geometry output. It's because when you returned your data e.g. in the WKB format by using the ST_AsBinary function, the column would be described by the statement.

    So review your SQL command and check if you're not returning raw geometry. If so, return proper geometry output instead.