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Reference/es_mbc_addfld
Syntax
int es_mbc_addfld( struct es_mbc *cls, const char *fieldnm, int ftype );
Arguments
struct es_mbc *cls |
A database class. |
|---|---|
const char *fieldnm |
Field name. |
int ftype |
Field type. Must be one of enumerated list of values below. |
Return Codes
ES_ERROR_NONE |
Success. No errors. | |
|---|---|---|
ES_ERROR_FIELDEXISTS |
Field name already exists in class. | |
ES_ERROR_UNKNOWNFIELDTYPE |
Invalid field type. |
Description
Add a field definition to a class. A field can be either numeric (integer or floating point), a reference to a node ( i.e. struct es_mbn* ) or a user-defined field. Integer fields can be designated as either 8bit, 16bit, 32bit or 64bits in size. Floating point fields are all double precision (64bits).
Character or string based data should be stored in a string dictionary (es_sd) and the corresponding integer stored as a numeric database field.
User-defined fields can be stored either as a pointer (void*) or as a fixed width blob of data up to 128 bytes in size.
Field Types
Each field requires a field type (int ftype) which can be one of the following:
ES_FLDTYPE_I8 |
8 bit integer. |
|---|---|
ES_FLDTYPE_I16 |
16 bit integer. |
ES_FLDTYPE_I32 |
32 bit integer. |
ES_FLDTYPE_I64 |
64 bit integer. |
ES_FLDTYPE_F64 |
64 bit double-precision floating point. |
ES_FLDTYPE_MBN |
Node reference (struct es_mbn*). This is not a child node field (these are added automatically by es_mbc_new()) but can be used as a general reference to any node in the database. |
ES_FLDTYPE_MBU |
User-defined field type stored as a pointer (void*). See es_mbc_addfldmbu(). |
ES_FLDTYPE_STR |
User-defined field type stored as a fixed width blob of data (typically type cast to a struct) up to 128 bytes in size. See es_mbc_addfldstr(). |