How to create fields in Python

[xtfmkh]

How to create fields in Python using wrapfiredac in python4delphi: When T = DBFireDac.T T.FieldDef.Add(feldname,type,size) :Add() takes exactly 0 arguments (3 given)

[FranciscoZanonDP]

The error "Add() takes exactly 0 arguments (3 given)" means you are attempting to call the Add() method on the T.FieldDef object with arguments, but the method in the Python wrapper for Delphi's FireDAC components is designed to be called without any arguments.

The correct way to create a field definition using wrapfiredac in Python4Delphi is typically to first create the TFieldDef object, set its properties, and then call the parameterless Add() to finalize it into the collection.

Here is the correct pattern, assuming T is your TFDQuery or similar FireDAC object:

1. Access the collection's new item creator

NewFieldDef = T.FieldDefs.Add()

2. Set the properties on the newly created object

NewFieldDef.Name = 'FieldName'
NewFieldDef.DataType = type
NewFieldDef.Size = size

No need to call Add() again, as the first step did the creation and addition

In short, use T.FieldDefs.Add() without arguments to create the object, then assign its Name, DataType, and Size properties.

[kjojo-112]

field_def = T.FieldDefs.Add()
field_def.Name = "YourFieldName"
field_def.DataType = ftString
field_def.Size = 50
field_def.Required = False
field_def.Precision = 0

[xianzhi311]

import clr # If using .NET, or use P4D's native imports (adjust per your setup)
from Python4Delphi import DBFireDac # Import FireDAC bindings

Step 1: Create a FireDAC component (e.g., TFDQuery)

fd_query = DBFireDac.TFDQuery(None) # Parent = None (or a form)
fd_query.Connection = your_firedac_connection # Assign your active FDConnection

Step 2: Access the FieldDefs collection

field_defs = fd_query.FieldDefs
field_defs.Clear() # Clear existing definitions

Step 3: Create a NEW TFieldDef instance and set its properties

new_field_def = DBFireDac.TFieldDef()

Set field properties (match Delphi's TFieldDef properties)

new_field_def.Name = "CustomerID" # Field name
new_field_def.DataType = DBFireDac.ftString # Data type (ftString, ftInteger, ftDateTime, etc.)
new_field_def.Size = 10 # Size (only for string/blob types)
new_field_def.Required = True # Optional: mark as required

Step 4: Add the configured FieldDef to the collection

field_defs.Add(new_field_def) # Add() takes the TFieldDef instance (0 positional args = no extra params)

Add another field (example: Integer)

new_field_def2 = DBFireDac.TFieldDef()
new_field_def2.Name = "OrderTotal"
new_field_def2.DataType = DBFireDac.ftInteger
new_field_def2.Size = 0 # Size irrelevant for numeric types
field_defs.Add(new_field_def2)

Step 5: Create the fields from the definitions (optional)

fd_query.CreateFields()

Cleanup (if needed)

new_field_def.Free()
new_field_def2.Free()