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Reference/es_mbb
struct es_mbb is an opaque data structure representing a field-binding collection. A program variable may be bound to a database field for the purposes of reading or updating a database. struct es_mbb is a collection of such bindings for some or all of the fields in a particular class.
Field bindings are used in conjunction with iterators (struct es_mbi) to populate, update or query a database.
There are two types of field-bindings:
| Binding by value | A program variable's value is copied to the database during an insert/update operation and a database field's value is copied to the program variable during a fetch operation. |
|---|---|
| Binding by reference | The address of (or pointer to) a database field's value is copied to the program variable during either an update or fetch operation. This is convenient for incremental updates, such as computing an aggregate value. |
The es_mbb interface contains functions to construct and destroy a field-binding as well as functions to bind database fields to program variables. A binding function exists for each combination of field type and binding type. A membership filter (struct es_mbm) may also be bound to a database field for use in filtered iterators ( see es_mbi_beginfetch() ).
| Constructing/Destroying | ||
|---|---|---|
| es_mbb_new | Create new field-binding for a particular class. | |
| es_mbb_delete | Delete a field-binding. | |
| es_mbb_mbm | Bind integer field to membership filter. | |
| Binding by value | ||
| es_mbb_i8_v | Bind a field of type ES_FLDTYPE_I8 by value. | |
| es_mbb_i16_v | Bind a field of type ES_FLDTYPE_I16 by value. | |
| es_mbb_i32_v | Bind a field of type ES_FLDTYPE_I32 by value. | |
| es_mbb_i64_v | Bind a field of type ES_FLDTYPE_I64 by value. | |
| es_mbb_f64_v | Bind a field of type ES_FLDTYPE_F64 by value. | |
| es_mbb_mbn_v | Bind a field of type ES_FLDTYPE_MBN by value. This includes both node reference and child node fields. | |
| es_mbb_mbu_v | Bind a field of type ES_FLDTYPE_MBU by value. | |
| es_mbb_str_v | Bind a field of type ES_FLDTYPE_STR by value. | |
| es_mbb_void_v | Bind a field of any type by value. | |
| Binding by reference | ||
| es_mbb_i8_r | Bind a field of type ES_FLDTYPE_I8 by reference. | |
| es_mbb_i16_r | Bind a field of type ES_FLDTYPE_I16 by reference. | |
| es_mbb_i32_r | Bind a field of type ES_FLDTYPE_I32 by reference. | |
| es_mbb_i64_r | Bind a field of type ES_FLDTYPE_I64 by reference. | |
| es_mbb_f64_r | Bind a field of type ES_FLDTYPE_F64 by reference. | |
| es_mbb_mbn_r | Bind a field of type ES_FLDTYPE_MBN by reference. This includes child node fields. | |
| es_mbb_mbu_r | Bind a field of type ES_FLDTYPE_MBU by reference. | |
| es_mbb_str_r | Bind a field of type ES_FLDTYPE_STR by reference. | |
| es_mbb_void_r | Bind a field of any type by reference. | |