Lexeme

This class represents a single search term or lexeme within a full-text search query. It supports advanced search features such as prefix matching, weight assignments, and logical inversion. The class handles the validation of search values and weights while providing the necessary logic to compile the lexeme into a formatted SQL string.

Attributes

Attribute	Type	Description
prefix	boolean	Boolean flag indicating if the lexeme should be treated as a prefix match in the search query.
invert	boolean	Boolean flag that determines whether to negate the lexeme match using a logical NOT operator.
weight	string	The importance ranking assigned to the lexeme, which must be one of 'A', 'B', 'C', or 'D'.

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Constructor

Signature

def Lexeme(
    value: str,
    output_field: [SearchQueryField](searchqueryfield.md?sid=django_contrib_postgres_search_searchqueryfield) = None,
    invert: bool = False,
    prefix: bool = False,
    weight: str = None
)

Parameters

Name	Type	Description
value	str	The string value of the lexeme.
output_field	[SearchQueryField](searchqueryfield.md?sid=django_contrib_postgres_search_searchqueryfield) = None	The field to be used for the output.
invert	bool = False	Whether to invert the lexeme search.
prefix	bool = False	Whether to treat the lexeme as a prefix.
weight	str = None	The weight of the lexeme (A, B, C, or D).

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Signature

def Lexeme(
    value: string,
    output_field: [Field](../../../forms/fields/field.md?sid=django_forms_fields_field),
    invert: boolean,
    prefix: boolean,
    weight: string
) - > null

Parameters

Name	Type	Description
value	string	The search term string; must be non-empty.
output_field	[Field](../../../forms/fields/field.md?sid=django_forms_fields_field)	The model field used to resolve the output type of this expression.
invert	boolean	Whether to negate this lexeme in the search query.
prefix	boolean	Whether to treat the lexeme as a prefix for partial matching.
weight	string	The importance weight assigned to the lexeme, must be one of 'A', 'B', 'C', or 'D'.

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Methods

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as_sql()

@classmethod
def as_sql(
    compiler: [SQLCompiler](../../../db/models/sql/compiler/sqlcompiler.md?sid=django_db_models_sql_compiler_sqlcompiler),
    connection: DatabaseConnection
) - > tuple

Generates the SQL fragment and parameters for the lexeme, including prefix, weight, and inversion modifiers.

Parameters

Name	Type	Description
compiler	[SQLCompiler](../../../db/models/sql/compiler/sqlcompiler.md?sid=django_db_models_sql_compiler_sqlcompiler)	The query compiler instance used to generate the SQL statement.
connection	DatabaseConnection	The current database connection used for backend-specific SQL formatting.

Returns

Type	Description
tuple	A tuple containing the SQL placeholder string and a list of formatted lexeme parameters.

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